Use of Alkali in Traditional Dyeing Technologies with Plants

Abstract

Ethnographic sources provide information about several dye plants that produced reddish colors; however, there is no information on how this process is accomplished. Combining information from written sources with the results of dyeing experiments enables a deeper understanding of the dyeing methods employed in the past. This paper gives insight into the effect of using alkali on obtaining reddish tones in dyeing with Potentilla erecta and Rumex sp. In dyeing experiments, wool yarn was dyed with plant extracts, and the chemical compositions were studied both in plant extracts and in extracts obtained from wool after dyeing. As a result, the red/red-brown color is obtained only under the influence of alkali. Analytical studies of procyanidin (PC) extracts from rhizomes and yarns were performed using infrared spectroscopy (FTIR-ATR) and liquid chromatography coupled with mass spectrometric detection (LC-DAD-MS). Procyanidin extracts of P. erecta and R. acetosa contained monomers identified as (+)-catechin and (-)-epicatechin, as well as dimeric procyanidins of type-A (m/z 575 [M−H]⁻) and type-B (m/z 577 [M−H]⁻), along with various types of trimers (m/z 865 [M−H]⁻; m/z 863 [M−H]⁻), which were also isolated from dyed wool yarns with a similar composition. The conducted research on the use of alkali with tannin-containing plants contributes to deepening our understanding of the perception of color that existed in the ancient rural environment.

1. Introduction

The use of natural dyes in textile dyeing has a long and rich history, revealing a diverse range of dyeing technologies. The knowledge accumulated in ancient times can be utilized as a resource today, particularly in the context of preserving a sustainable living environment, where the use of environmentally friendly textile dyes plays a significant role [1]. The traditional dyeing methods passed down from generation to generation, which European peasants used to dye their fabrics and yarns, still preserve little-explored dyeing techniques, such as the use of alkali. The study of Latvian ethnographic heritage, or, on a broader scale, the region of North-Eastern Europe, can provide new insights into the diversity of natural dyes.

Red dye has always been of great cultural and historical significance [2]. However, until now, researchers have focused more on commercially important red dyes, such as madder, cochineal, and brazilwood, among others. Here, attention is focused upon the red color noted in the Latvian ethnographic materials, specifically—the cases where lesser-known plants are identified as the source of this color. Latvian ethnographic written sources provide information about more than 20 local plants associated with the possibility of dyeing wool yarn in reddish tones, which is the primary interest for this paper. The current article mainly presents the study of two dye plants. These are the red sorrel (in Latvian: pļavas skābene, skābene) Rumex acetosa L. (Figure 1a) and tormentil (in Latvian: stāvais retējs, retējs, retējums) Potentilla erecta (L.) Raeusch (Figure 1b). Both R. acetosa and P. erecta are common in the wild in Europe [3,4], but their habitats are different. In Latvia, they are not included in the list of protected plants and are not subject to restrictions on use [5]. Both plants are rich in tannins [6,7,8], and P. erecta is more commonly known as a medicinal plant than a dye plant because of its composition [9].

P. erecta is also known as a dyeing or tanning plant in the traditional cultures of other European peoples [10] (p. 3651) and [11]. A significant study of ancient dyeing methods using local plants, including P. erecta and R. acetosa, is the dissertation of Finnish researcher Krista Vajanto (now Wright) [12]. In her study, P. erecta was used as a dye to produce red, while R. acetosa was primarily used as a natural mordant. In general, R. acetosa is not mentioned as a dye plant in the scientific literature.

The research was conducted by combining the methodologies of both the humanities and the natural sciences. Following historical research methods in the humanities, information on natural dyeing, dyes, and colors obtained from different plants was collected and analyzed through written historical sources, both unpublished and published. Both of them primarily reflect the dyeing tradition practiced in the 19th and 20th centuries. However, there is also some evidence about earlier centuries. There are no publications that would confirm that the dye of P. erecta or R. acetosa has been identified in historical artefacts (both archaeological and ethnographic) in Latvia.

The set of unpublished written sources consists of materials from ethnographic expeditions. The information in Latvia was obtained during fieldwork organized by the Board of Monuments between 1924 and 1942. It consists of questionnaire-style interview notes on specific textiles, as well as information recorded in the form of a free narrative (more about this see: [13] (pp. 64–65)). Today, these materials are stored in the Latvian National Museum of History, the Department of Ethnography. This article has benefited from the information found in two sections of the collection: “Dyeing, washing, bleaching” (LNVM ZAE folder 47) [14] and “Female folk dress” (ibid., folder 35) [15].

Published sources are texts in the press about dyeing textiles with plant dyes. The oldest information in the Latvian press about dyeing textiles with local plants dates back to 1768 [16]. However, only one plant is mentioned there—alder branches with leaves. In the 19th century, German (the upper class of society in the Baltic provinces of the Russian Empire was mainly German-speaking) and Latvian press advertisements of merchants provided information about various goods, including imported dyes and mordants. Purposefully compiled information about the natural dyeing of Latvian peasants began to be published in the Latvian press later, at the turn of the 19th and 20th centuries [17,18,19,20]. However, more such publications can be found in the 1920s and 1930s. These texts document traditional cultural heritage, including skills that have already been partially forgotten. Among the written sources is Martha Bielenstein’s book [21], which compiles information on the use of dye plants, obtained from various sources, including materials collected by the author herself.

The specificity of the preserved written sources is that they usually provide only general information, indicating solely the dye plant and the color obtained. The dyeing process itself is rarely described. However, we can find such information, including the amount of dyes and liquids, as well as the time of heating, in publications in the Latvian press from the 1920s to the 1930s. The ethnographic materials collected by Bielenstein also provide insight into dyeing methods [21] (pp. 111–161). Although Latvian ethnographic sources rarely contain precise records of dyeing recipes, the overall dyeing methods can be understood to facilitate the realization of dyeing experiments. Nowadays, the combination of academic knowledge with practical experiments based on craft experience is playing an increasingly important role in color research [22] (p. 4). Meanwhile, the experimental method used in this study also shares many similarities with experimental archaeology [23,24]. A prerequisite for the adequate use of information found fragmentarily in written sources in the creation of new knowledge is the practical experience, knowledge, and skills of the researchers themselves. Since information about natural dyeing methods in ethnographic sources is fragmentary and lacking in precise detail, the research was based on dyeing experiments. Chemical analyses of dye solutions and dyed yarns provide additional information about the dyeing process under study.

The triterpenoids, phenolic carboxylic acids, and flavan-3-ol derivatives are primarily biosynthesized in the young shoots and leaves of P. erecta and R. acetosa, while procyanidins have been predominantly found in the roots [25,26]. Several types of procyanidins are identified, with type-B typically indicating the covalent linkage between C4/C8 and the flavan-3-ol units, while type-A has an additional bond linking the atom at position C-2 to C-7 [27]. A comprehensive review of Potentilla by Tomczyka and Latté [6] presents a few configurations of procyanidins found in the tormentil roots and rhizome. A study of water-soluble compounds revealed that the rhizome extract contained 54.7% (w/w) total tannins, primarily composed of procyanidins [7]. Tormentil is notably rich in procyanidins, particular with a predominant content of oligomers [25], along with dimers such as B3, B6, 3,4-cis-(+)-catechin-(4α-6)-(+)-catechin (3,4-cis-B6), and (+)-catechin-[6′,6]-(+)-catechin [28]. According to the article by Bicker and colleagues [26], the procyanidin obtained from the aerial parts of Rumex acetosa mainly consists of type-B dimers (such as B1, B2, B3, B4, B5, B7), while type-A dimers were present in the form of one dimer and one trimer (A1; epicatechin-(2β → 7, 4β → 8)-epiaphselechin-(4α → 8)-epicatechin). The results from the extraction procedures, indicated that procyanidins A2, B5, and B7 had contents of 6.8, 4.8, and 5.6 mg kg⁻¹ DW (per extract), respectively.

Liquid chromatography coupled with mass spectrometry is commonly used to identify PC oligomers. Monomers and small oligomers can be separated using normal- or reverse-phase stationary phases based on silica or polymer, employing a gradient of eluent [29]. The purification of flavan-3-ols, procyanidins, and their conjugated compounds from extracts is achievable in combination with solid-phase extraction, utilizing Supelco HW-40F [30], Sephadex LH-20 [31], or Amberlit XAD-7 [32].

Combining information from written sources with the results of practical dyeing experiments and chemical analyses provides a deeper understanding of the dyeing methods employed in the past.

2. Materials and Methods

2.1. Informative Sources and Materials

2.1.1. Information from Written Sources

As one of the earliest Latvian ethnographers, the first who started collecting ethnographic materials on natural dyeing, Miķelis Skruzītis (also: Mikus Skruzits) (1861–1905) mentioned Tormentil as a dye-plant in 1895: “For dyeing the red tone, brownish red, […] the roots of tormentil were used, for which the plant itself was used, and only its roots.” [19] (p. 12). Similar information is found in other publications by Skruzītis [21,33]. In the 1920s and 1930s, several authors whose publications address dyeing with plant dyes also mentioned tormentil: “Tormentil is found in forests, meadows, and fields. The roots, which give yellow, red, and black colors, are used in dyeing.” [34]. The indications that tormentil can be used for achieving a reddish brown color in dyeing are also found in other press publications of the time [35], conforming with the information about dye plants compiled by Bielenstein [21] (pp. 104, 109).

Unpublished written sources indicate that tormentil root was used to produce specifically a red, not reddish-brown, color: “If [the girl] had black hair, then red stripes [in her skirt]. Woollen yarn [for them] was dyed in tormentil roots; only wool could be dyed.” [36].

Likewise, the sources written in the 1930s contain information about the use of sorrel Rumex sp. for obtaining a red or, more precisely, reddish-brown color: “Sorrel (Rumex acetosa)—roots—brown-red, whole plant—brown and black colours.” [37]. The book by Martha Bielenstein also contains similar information: “Rumex acetosa; German: Sauerampfer, Latvian: skābenes. Roots, leaves, and flowers: brown to reddish-brown.” [21] (p. 105). Moreover, the 1943 source states the same: “[…] from the sorrel roots—red-brown” [38].

The presence of tannins is the reason for the use of both plants to produce black and greenish-grey dyes, which are also noted in written sources: “Sorrel (Rumex) is used fresh; gives a permanent [i.e., lasting] black dye.” [34]; “Sorrel (Rumex). Found everywhere. Used fresh, gives a black dye.” [35]; “Potentilla silvestris. Stem: yellow; root: red; whole plant: black.” [21] (p. 109).

The sources do not contain a precise indication regarding the dyeing method used to obtain the reddish-brown color from these plants. Practical dyeing experiments were conducted to establish the colors obtained from P. erecta and R. acetossa.

2.1.2. Dye Plants

For the dyeing experiments, the researchers selected plants indicated in ethnographic sources [14,33,34,35] and [21] (pp. 104–105) that were available in sufficient quantities in the surrounding environment. Since the plant root was used for dyeing, it was important that the plant was common in the particular location and that its use for dyeing would not endanger the population of the species. The roots of sorrel R. acetossa (Figure 2a) were collected in spring, at the beginning of the growing season, in the first days of May 2024. Meanwhile, the roots of tormentil P. erecta (Figure 2b) were collected at the end of the vegetation period, in late August 2024.

The collection time of the roots is linked to natural processes because at the beginning of the vegetation period, the plant has not yet used all the reserves of active substances accumulated in the previous season. In contrast, at the end of the vegetation period, it has accrued reserves for the next season. However, which plant was collected in spring and which in autumn was random. Both fresh (tormentil) and dried (sorrel) dye plants were used in the experiments, because it was not always possible to conduct dyeing experiments immediately after collecting the plants. Furthermore, ethnographic sources confirm that both fresh and dried plants, as well as their parts, were used for dyeing [14]. Empirical knowledge accumulated in more than 15 years of dyeing experience by Karlsone confirms that the use of fresh or dried plants has an insignificant effect on the final dyeing result.

2.2. Chemicals

Since the aim of the research is both to learn more about the dyeing methods used in the past and to adapt ancient recipes to modern use, the experiments used both the mordants mentioned in ethnographic sources, such as alum, copper vitriol and iron vitriol [14,39], and tin salt, the use of which in natural dyeing in Latvia has been mentioned since the 1940s [40]. In the dyeing experiments, several metal salts were used as mordants. They were as follows: alum (kalium aluminum sulfate) KAl(SO₄)₂ with modifier cream of tartar KC₄H₅O₆; tin salt (tin chloride) SnCl₂ · 2H₂O; copper vitriol (copper (II) sulfate) CuSO₄ · 5H₂O; iron vitriol or copperas (iron (II) sulfate) FeSO₄ · 7H₂O. They were purchased from the Latvian Chemical Society “Enola” (http://enola.lv/ accessed on 16 June 2025).

Reference compounds (Figure 3) of ellagic acid, (+)catechin [0976 S], (-)-epicatechin [0977 S], (-)-epicatechin-(4β-8)-(+)catechin (B1) [0983], (-)-epicatechin-(4β-8)-(-)-epicatechin (B2) [0984], (+)-catechin-(4α-8)-(+)catechin (B3) [0987], (+)-epicatechin-(4β-8,2β-O-7)-epicatechin (A2) [0985 S], and (-)-epicatechin-(4β-8)-(-)-epicatechin-(4β-8)-(-)epicatechin (C1) [0988] were purchased from Extrasynthese (Genay, France), but (+)-catechin-(4β-8)-(+)-catechin-(4β-8)-(+)-catechin (C2) [HY-N7521-1] was pursed from Cayman Chemical (Michigan, IN, USA). All solvents and mordanting reagents were of the highest quality and sourced from Sigma-Aldrich (Labochema Latvija, Latvia).

2.3. Methods

2.3.1. Dyeing Experiments

The dyeing experiments were based on information gathered from various ethnographic sources on the use of alkali in the dyeing process [14,21] (pp. 114–115), as we do not have a single, precise description of a specific historical method. Experiments were developed by combining information from several written sources and previous dyeing experience, for example, with Bixa orellana L. [41]. Since soaking plants in lye resulted in reddish-color tones, it was decided to conduct experiments using an alkaline solution this time, as well. Furthermore, Bielenstein reported that the root of tormentil in conjunction with alkali gives a brown color [21] (p. 138). As noted by Dominique Cardon, plants containing tannins (phlobatanins) give reddish tones when exposed to alkali [42] (p. 409). However, it is not known whether this also applies to R. acetosa and P. erecta. In order to determine the effect of alkali and water on the extraction of the dye, parallel dyeing experiments were performed. Two different dye solutions were prepared. One was obtained by soaking the plant parts in ordinary, pH-neutral water, and the other was made by soaking in strong alkali (pH 13), which was obtained from wood ash.

Since the study employs the method of experimental ethnography, where the imitation of previously used working methods is crucial, this time, as well, alkali obtained traditionally was used, rather than a chemically pure substance from the laboratory. In the past, many household activities were closely interrelated, saving time and resources, including labor and materials. It was well-known that the ashes of deciduous trees are “stronger” than those obtained from coniferous trees. The strongest alkali is obtained from birch ash, but high-concentration alkali can also be obtained from other species of deciduous trees. However, wood was not burned only to obtain ash alkali. The ash that remained after the kitchen hearth or room heating stove was used. For the preparation of ash alkali, based on the information provided by ethnographic sources [21] (p. 73, pp. 114–115) and [43,44], as well as on Karlsone’s inherited knowledge of traditional craft skills and previous experience, deciduous ash from the kitchen hearth was used. Boiling water was poured over the ashes (the volume of sifted ashes was approx. 8 L, the amount of water was 10 L), and then, the mixture was left to soak for >24 h until a clear liquid formed on the surface. By pouring off this liquid and diluting it with plain water, an alkaline solution for soaking dye plants was obtained. The pH 13 of the alkali was determined based on several considerations. Firstly, the fact that alkali of such strength fully corresponds to the designation mentioned in ethnographic records: “strong alkali” [21] (p. 137). Second, when measuring the liquid that had settled on top of the ashes after pouring hot water on them and leaving them for at least 24 h or longer, a reading of pH 14 was obtained. For soaking the plants, the alkali solution was diluted with ordinary water to a pH of 13. For pH measurements, four-tone combinations “Universal indicator papers pH 0–14” from the company Chempur (offered by “Enola” (http://enola.lv/ accessed on 16 June 2025) were used.

In the dyeing experiment, we used wool yarn from local sheep raised in Latvia, but we do not know their exact species. The wool yarn was spun at a wool spinning mill in Preiļi (a small town in eastern Latvia), where wool is purchased from local sheep farms. Before dyeing, we washed the yarn with a modern detergent designed for washing wool products. After washing, the yarn was thoroughly rinsed in several rinse waters. Five wool yarn samples, each weighing 5 g (weight refers to dry yarn), were used for each solution. Before dyeing, the yarn was soaked in clean water for several hours. The following mordants were used in the experiment for wool samples:

(1)

Without mordanting;

(2)

Premordanted with alum and cream of tartar (8 g KAl(SO₄)₂ + 7 g KC₄H₅O₆/100 g fiber);

(3)

Premordanted with tin salt (5 g SnCl₂ · 2H₂O/100 g fiber);

(4)

Mordanted with copper vitriol (copper (II) sulfate CuSO₄ · 5H₂O) during dyeing;

(5)

Mordanted with iron vitriol or copperas (iron (II) sulfate FeSO₄ · 7H₂O) during dyeing.

The researchers used 300 g of chopped, dried R. acetosa roots for each of the dye solutions: (1) the plant was soaked in plain water for 48 h, resulting in a solution with a pH of 5.5; (2) the same amount of roots was doused with a strong (pH 13) alkali for 48 h, during which time the alkalinity of the liquid decreased significantly, reaching a pH of 6.

In the dyeing with P. erecta, the researchers used 548 g of fresh root, which corresponds to ~300 g of dried root. Using an approach that was similar to the previous dyeing experiment with R. acetosa, the researchers soaked the chopped roots in the following: (1) plain water and (2) an alkaline solution derived from wood ash. After 24 h, the dye dissolved in water had a pH of 5.5, while the roots soaked in alkali remained highly alkaline. Only after 72 h did the liquid reach a pH of 6. In the process where the dye is extracted in an alkaline solution, it is necessary to wait until the liquid becomes pH neutral or slightly acidic before it can be used for dyeing yarn. Heating the yarn in a strongly alkaline liquid causes damage to the structure of the wool fiber by the alkali and therefore is detrimental to the quality of the yarn. This must be avoided.

The liquids, containing the plant parts, were heated to boiling point and then boiled for 2 h. The dye solution was then drained and left to cool.

The materials prepared for coloring were immersed in the cooled (25–30 °C) dye liquid for an hour. After that, the heating of the dye liquids was started. The solution was heated to 85 °C, and heating continued at this temperature for one hour.

2.3.2. Dyestuff Extraction Methods

For the extraction of procyanidins, an alkaline-aqueous solution (ash, pH 13, after 72 h—pH 6) from the 5- and 2-day maceration of P. erecta and R. acetosa rhizomes, as well as a 2-day maceration of the rhizome in water, was used. The extracts were subsequently used to dye wool and to investigate their chemical composition. The cross-linked polystyrene copolymeric resin Amberlite™ XAD-7HP was used for the fractionation of the solution and the isolation of procyanidins. Conditioning and equilibration of the resin were performed using 4 column volumes (CV) of 0.1% HCl in water, followed by 4 CV of deionized water. The crude macerate solution (10 mL) was filtered and applied to a conditioned fractionation resin (100 g in a column) and washed with water. To desorb the retained compounds (reddish brown fraction), a 1.0% formic acid methanol solution was utilized [45]. After collecting the procyanidins eluate, the residual fraction was completely eluted using a dichloromethane–methanol–water (DCM/MeOH/H₂O) (1:1:1, v/v/v) mixture. Fractionation of the macerate via column chromatography on an XAD-7HD using stepwise elution yielded 3 fractions. The collected eluate fractions underwent drying via rotary evaporation.

Dyes were extracted from the yarn using dimethyl sulfoxide (DMSO) [46]. To each yarn sample (approximately 50 mg), 1.0 mL of DMSO was added, and the mixtures were maintained at 80 °C for 25 min. The resulting extracts were filtered through a 0.45 μm membrane filter prior to ultra-high performance liquid chromatography (UPLC) analysis.

2.3.3. Instrumentation

A UPLC system coupled with an Acquity™ PDA eλ photodiode array detector and an Acquity™ TQD tandem quadrupole mass spectrometer equipped with a Z-spray electrospray interface (Waters, Milford, MA, USA), was utilized. Separation (2 μL) was performed on a UPLC BEH™ C18 column (1.7 μm, 2.1 mm × 150 mm) at 35 °C. The mobile phase consisted of solvent A—10 mM ammonium acetate (89.7%), B—methanol (10.0%), and solvent C—formic acid (0.3%, unchanged), applied at a flow rate of 0.25 mL min⁻¹ using the following gradient elution mode: 0–15.0 min, 10.0–53.9% B; 15.0–15.15 min, 53.9–79.8% B; 15.15–16.50 min, 79.8% B; 16.51–20.0 min, 10.0% B. The electrospray ionization (ESI) parameters such as the capillary voltage, cone voltage, source temperature, desolvation temperature, cone gas (N₂) flow, and desolvation gas flow were set at 3.5 kV (ESI-), 25 V, 150-C, 400-C, 50 L/h, and 800 L/h, respectively. For quantification, data were collected in the selected ion monitoring (SIR) mode, tracking the mass ions for each compound and using external calibration curves. The selected primary quantitation ions (QIs) were m/z 289 [M−H]⁻ (monomers), m/z 577 [M−H]⁻ (procyanidin dimers, B type), m/z 575 [M−H]⁻ (procyanidin dimers, A-type), m/z 865 [M−H]⁻ (procyanidin trimers), m/z 863 [M−H]⁻ (procyanidin trimers, A/B type), and m/z 301 [M−H]⁻ (ellagic acid) in the method. The limits of quantification (LOQ) were 38.0 for B1, 32.0 for B2, 29.8 for B3, 26.3 for C1, 40.2 for C2, 25.8 for A2, 47.6 for catechin, 48.0 for epicatechin, and 0.8 µg mL⁻¹ for ellagic acid.

The Fourier-transform infrared spectroscopy (FTIR) spectra of the procyanidin fraction were recorded in pressed KBr (1:100 w/w) on a Shimadzu™ IR-Tracer 100 spectrometer (Shimadzu, Japan) over a spectral range of 4000 to 500 cm⁻¹ with a resolution of 4 cm⁻¹ and 10 scans. The instrument was controlled using LabSolutions IR Ver2.21 software.

The spectral reflectance of the dyed fibers was measured using a Sensogood spectrophotometer (Portable Color Spectrometer, Gujarat, India) as an illumination source, which serves 98+ CRI true color full spectrum LEDs. The CIELab values (L*, a*, b*, C*, h°) were also recorded for all dyed yarns along with the controlled sample (L* = 98.11, a* = −1.55, b* = 6.45). The CIE color difference was calculated using the following equation: ΔE = [(ΔL*)² + (Δa*)² + (Δb*)²]^1/2, where L*, a*, and b* are the color values in the CIE L*a*b* color space [47].

3. Results

3.1. Color Tones

3.1.1. Colors Obtained with R. acetosa

The result of the experiments performed with the roots of R. acetosa is 10 different color tones, which are shown in

Table 1. Range of tones obtained by dyeing with R. acetosa.

Mordants	Dyestuff Soaked in Water	Dyestuff Soaked in Alkali
Without mordanting
KAl(SO4)2 + KC4H5O6
SnCl2 · 2H2O
CuSO4·5H2O
FeSO4·7H2O

.

3.1.2. Colors Obtained with P. erecta

The result of the dyeing experiments with roots of P. erecta is 10 different color tones, which are shown in

Table 2. Range of tones obtained by dyeing with P. erecta.

Mordants	Dyestuff Soaked in Water	Dyestuff Soaked in Alkali
Without mordanting
KAl(SO4)2 + KC4H5O6
SnCl2 · 2H2O
CuSO4·5H2O
FeSO4·7H2O

.

The obtained dye samples show that the extraction of the dye in an alkaline solution resulted in more reddish tones than when the dye was extracted in water. For an improved, more profound understanding of the dyeing method used and the resulting color tones, the researchers performed chemical analyses of the dye solutions and dyed yarn samples.

3.2. Chemical Analyses

To identify the presence of procyanidin compound groups in the aqueous and alkaline (ash) macerate of the P. erecta and R. acetosa rhizomes, FTIR measurements of the fractions separated through the XAD-7 HP resin were performed (see

Table 3. Content (mg g⁻¹ dry matter (DM)) of compounds found in the fractionated dye solution of R. acetosa and P. erecta, prepared previously through plain aqueous and alkaline–aqueous maceration.

Eluent	Fraction	Potentilla erecta		Rumex acetosa
		Solution of Dyeing
		Alkaline-Aqueous	Aqueous	Alkaline-Aqueous	Aqueous
H2O	1	220.9 ± 10.8	88.6 ± 4.2	47.1 ± 1.6	43.1 ± 1.8
1.0% FA in MeOH	2	131.2 ± 6.8	84.1 ± 4.1	21.5 ± 0.9	40.9 ± 1.5
DCM/MeOH/H2O	3	67.9 ± 3.7	43.7 ± 2.0	12.2 ± 0.4	14.1 ± 0.7

Data are expressed as the mean ± SD at a significance level of p < 0.05.

). The procyanidins fraction and pure catechin hydrate (procyanidin unit) were evaluated using an FTIR spectrophotometer with an absorption range of 400–4000 cm⁻¹, as illustrated in Figure 4. Characteristic peaks of catechin were observed at 3398 (phenolic hydroxyl group), 1618, 1520, 1473, 1444 (phenyl ring), 1130, and 1005 (stretching vibrations of C–O–C) cm⁻¹. The peak at 2860–2920 cm⁻¹ is associated with the symmetric and antisymmetric -C-H- stretching vibrations of CH₂ and CH₃ groups. All the spectra of the macerated rhizome procyanidin fractions in different solutions shared certain similarities. A broad band due to the OH stretch is observed in the range of 2930–3650 cm⁻¹. At 1510–1530 and 1415–1455 cm⁻¹, a band due to -C–C- aromatic compounds is detected, according to the bibliography [48]. The peak at 1629 cm⁻¹ is characteristic of aromatic compounds with a conjugated double bond, representing the C–C stretching vibration observed at a peak of 837 cm⁻¹. The IR bands in the range of 600–1300 cm⁻¹ are associated with substituted benzene rings, generally indicating the presence of the chemical structures of flavonoids. Procyanidins contain some aromatic esters, as indicated by the signal characteristics of carbonyl groups (>C=O stretching and C–O), which are also observed in the spectra of rhizome fractions at 1714 cm⁻¹ and 1211 cm⁻¹, respectively. The absorption bands centered at 779 and 1148 cm⁻¹ are associated with out-of-plane and in-plane bending vibrations of the -C-H aromatic bond, respectively. It is noteworthy that the peaks of the spectrum of the procyanidin fractions showed a merging and decreased intensity in the same range as the catechin spectrum, suggesting an intramolecular interaction among oligomer forms [49]. An almost identical FTIR spectral profile of procyanidins was observed in the bark of Pinus radiata Chang Sub Ku [50], which reported indicative values of the absorption band values of the procyanidin extract.

Although procyanidin compounds are considered among the most unstable with respect to temperature effects [51], they play a role in color formation. Therefore, it is important to understand their chemical composition and the mechanisms by which they bond to the fiber. Macerating the rhizome in alkali promotes the hydrolysis of glycosides, resulting in a higher extraction yield since tannins and flavan-3-ols can exist in the form of glycosides. Alkaline-aqueous extraction is particularly effective for P. erecta rhizome, which has a higher yield of extractive matter compared to R. acetosa (Table 3), although the outcome of this process may be influenced by the shortened maceration time of R. acetosa to two days (an active fermentation process). Of the three fractions derived from the extract of the rhizomes, only the second fraction (2) shows the presence of procyanidins, while the primary fraction (1) of water and the last fraction (3) of DCM/MeOH/H₂O show little or no content as indicated via FTIR and UPLC-MS.

The use of chromatography to separate a test mixture of dye solutions is demonstrated using the reverse-phase (RP) column. The separation of procyanidins and their isomeric forms shows that the peak symmetry factor (As—0.7) and retention time (total time 20 min) are optimal with a mobile phase modified with formic acid and ammonium acetate. Referring to the published mass spectra of procyanidins in peanut skin, the compounds in the dye solution were identified as procyanidin dimers and trimers, structured as EC(C)-EC(C)C and EC(C)-EC(C)-EC(C), respectively [52]. The content of procyanidins found in the dye solution of R. acetosa and P. erecta, pre-prepared via aqueous and alkaline–aqueous maceration, is shown in

Table 4. Fractionation yield (mg g⁻¹ dry matter) of various prepared dye solution from P. erecta and R. acetosa.

Species	Polymeric PCs	Abbr.	RT	[M−H]−	Content, mg g−1 DM
					Aqueous	Alkaline
R. a.	C → B → C → B → C	C2	4.4	865	<LOQ	<LOQ
P. e.					11.3 ± 1.5	<LOQ
R. a.	C → B → C	B3	4.5	577	<LOQ	1.0 ± 0.1
P. e.					38.7 ± 1.8	<LOQ
R. a.	C	C	5.8	289	2.8 ± 0.7	1.5 ± 0.1
P. e.					39.1 ± 1.9	18.8 ± 0.5
R. a.	EC → B → EC	B2	6.5	577	18.9 ± 1.4	0.6 ± 0.1
P. e.					<LOQ	<LOQ
R. a.	(EC)C → B → (EC)C → A → (EC)C		6.6	863	10.8 ± 1.3	<LOQ
P. e.					<LOQ	<LOQ
R. a.	EC → B → EC → B → EC	C1	7.7	865	18.0 ± 1.2	<LOQ
P. e.					<LOQ	<LOQ
R. a.	(E)C → A → (E)C		7.9	575	<LOQ	1.3 ± 0.1
P. e.					6.4 ± 0.6	23.1 ± 0.6
R. a.	EC	EC	8.2	289	17.0 ± 1.4	1.0 ± 0.1
P. e.					8.9 ± 0.5	10.7 ± 0.5
R. a.	(E)C → B → (E)C → A → (E)C		8.5	863	3.2 ± 0.3	1.0 ± 0.1
P. e.					<LOQ	<LOQ
R. a.	(E)C → A → (E)C		9.6	575	<LOQ	0.8 ± 0.1
P. e.					<LOQ	17.8 ± 1.2
R. a.	(E)C → B → (E)C		10.7	577	2.6 ± 0.3	<LOQ
P. e.					<LOQ	<LOQ
R. acetosa	Total procyanidins (mg g−1 DM of dye)				73.3 ± 9.7	7.2 ± 0.7
P. erecta					104.4 ± 6.5	81.8 ± 2.8

RT—retention time, min; [M−H]⁻—molecular ion, m/z; C—catechin; EC—epicatechin; A—linkage between monomer units, which can be 4,8-, 2,7- or 4,6-, 2,7-; B—linkage between monomer units, which can be 4,8-, 6,6′-, or 4,6-, 6′,8-; Abbr.—the abbreviations of the identified procyanidins. The limit of quantitation (LOQ) for unidentified dimers and trimers was quantified based on B1 and C1 calibration, determined as 0.30 and 0.62 mg g⁻¹ (S/N > 10, RSD (% < 1), respectively.

. In comparison, the retention time (RT 6.5 min) indicates that the dimer of procyanidin B1 was not detected in any of the extracts, while B3 procyanidins (RT 4.4 min, m/z 577 [M−H]⁻) were identified in high amounts (38.7 ± 2.0 mg g⁻¹ DM) in the P. erecta procyanidin fraction, whereas B2 (RT 6.5 min, m/z 577 [M−H]⁻) was only detected in solutions of R. acetosa fractions (18.9 ± 3.9 mg g⁻¹ DM). The analysis revealed that these species contained similarly high levels of monomers identified as catechin (RT 5.9 min, m/z 289) and epicatechin (RT 8.2 min, m/z 289), but with different distributions. A relatively higher percentage of catechin was found in the procyanidin extract of P. erecta (38.1% (Aq), 27.5% (AL)) compared to R. acetosa, where epicatechin predominated (27.3% (Aq), 11.3% (AL)). Procyanidins B2, B3, and C2 are reported to be present in parts of P. erecta [6], while B1, B2, B3, and C1 were found in the extract from the aboveground parts of R. acetosa [26]. The RT and MS data are consistent with the absence of procyanidin C1 in P. erecta extracts, which was also confirmed in the present study.

Additionally, it was noticed that extracts with water produced similar tones on wool, featuring a light-yellow color “Mellow Apricot” (L* = 77.28, a* = 12.05, b* = 39.98) for R. acetosa and the color “Fawn” (L* = 77.59, a* = 14.86, b* = 38.94) for P. erecta (see

Table 5. Average CIE color coordinates of dyed yarn by varying metal mordant types and dye solution types.

Mordant	Dye Typ	Rumex acetosa						Potentilla erecta
		L*	a*	b*	c*	h°	ΔE	L*	a*	b*	c*	h°	ΔE
Unused	Aq	77.28	12.05	39.98	41.75	73.23	41.75	77.59	14.86	38.94	41.68	69.11	41.79
	AL/Aq	71.06	14.55	30.58	33.87	64.56	35.41	60.05	24.66	27.85	37.19	48.47	50.93
CuSO4	Aq	35.88	19.37	35.07	40.06	61.09	71.62	51.18	10.08	17.86	20.51	60.57	49.68
	AL/Aq	16.57	25.62	21.38	33.37	39.85	87.24	29.65	20.77	21.13	29.63	45.49	73.49
FeSO4	Aq	53.13	−0.33	18.02	18.03	91.06	46.46	55.86	9.57	3.57	10.22	20.47	43.78
	AL/Aq	34.63	2.02	6.65	6.95	73.11	63.58	49.90	16.26	−1.08	16.30	356.19	51.94
SnCl2	Aq	83.07	13.20	42.09	44.12	72.59	41.40	79.82	14.59	24.54	28.55	59.27	30.37
	AL/Aq	69.74	31.70	25.45	40.65	38.76	47.66	51.21	32.54	27.95	42.89	40.66	61.84
KAl(SO4)2	Aq	88.70	5.90	31.53	32.07	79.41	27.80	83.30	9.37	25.60	27.26	69.04	26.56
	AL/Aq	73.69	26.26	23.74	35.40	42.12	40.85	39.95	27.31	20.58	34.20	36.99	66.45

Aq—aqueous solution; AL—alkaline; ΔE—color difference between the dyed and undyed wool; calculations were made based on Robertson [47]; CIE—International Commission on Illumination. Measurements were performed under D65 illumination with a 10° standard observer (D65/10°).

). The color difference (∆E) was calculated between undyed and dyed samples. The results indicate that the color differences increased with dye mordanting. The change in saturation (c*) was observed to a more or lesser extent for each mordant used, but the lowest measurement was shown with iron (II), particularly for R. erecta. More noticeable differences in the color range were observed with an alkaline solution, where skeins of yarn dyed with the P. erecta solution acquired a more reddish hue, “Light Salmon” (L* = 60.5, a* = 24.66, b* = 27.85). The most vivid red color, “French Puce”, is prominent for the P. acetosa yarn dyed in aqueous–alkali macerate with copper (II) post-treatment, as well as the color “Brown Rust”, obtained by dyeing yarn in R. erecta aqueous–alkali macerate with tin (II) post-treatment. The tone was intensified to a more reddish-brown color by mordanting the yarn with tin (II) chloride, both when using an aqueous dye and an alkaline–aqueous solution.

A common feature of using mordant tin (II) before dyeing yarn is the predominant presence of procyanidin monomers in the yarn extract, formed by the competition between catechin and epicatechin, resulting in very similar tones after treatment with dye solutions from both plants.

In aqueous solutions, tin (II) exists as a complex ion and tends to hydrolyze to form tin (II) hydroxide, a process that is enhanced in alkaline solutions to produce sodium stannite (Na₂SnO₂). In aqueous solutions, condensed and hydrolysable tannin penetrates the fibers, and the subsequent application of metal salts results in complex formation. In aqueous solutions, condensed and hydrolyzable tannin integrates into the fibers, and the following application of tin salts results in the creation of complexes with one or two PC monomers or oligomers containing a six-coordinated tin center. The four coordination sites of the central tin atom are occupied by four oxygen atoms, while the remaining two sites are occupied by bridging oxygen atoms.

Figure 5 illustrates the total ion chromatography (TIC) profiles of P. erecta and the individual procyanidin content of the yarn extract dyed in plain aqueous and alkaline–aqueous solutions, without mordanting. Catechin and epicatechin, as well as three type-B procyanidin dimers (m/z 577 [M−H]⁻), including the identified B3, were extracted from the yarn (see Table 4). One degradation product of hydrolyzable tannins, specifically ellagic acid, was identified in DMSO extracts of P. erecta yarns obtained from both alkaline and non-alkaline aqueous dyeing solutions. The absence of ellagic acid in aqueous dyeing solutions and the skeins of yarn colored in them is attributed to its limited solubility in water (0.82 g L⁻¹ [53]), but it was detected in all DMSO yarn extracts. This finding indicates the degradation of high-molecular hydrolyzable tannins bound in the yarn fibers due to light, temperature, and other environmental factors. The composition of extracted procyanidins is similar in fiber extracts dyed in both aqueous and alkaline–aqueous solutions and mordanted with FeSO₄ and CuSO₄.

Figure 6 presents the ion chromatography (TIC) profiles with SIR mode-registered compounds at m/z 289, 577, 575, 301, and 865. The components were identified based on the retention time of the standard compounds and their characteristic molecular ions (Figure 6C). The composition of the main compounds in the extract is similar to that of the dye solution, predominantly featuring catechin (5.8 min), epicatechin (8.1 min), and two kinds of type-B dimers (m/z 577 [M−H]⁻), which eluted at 7.9 and 9.5 min. The study indicates that the highest interaction between the fiber and the uptake components of the rhizome macerate occurs when the fibrous wool is modified with copper (II) cations, which is reflected by the low quantitative yield of the desorbed DMSO substrate. Overall, the composition of procyanidins differs minimally from that extracted from the yarn. In the case of tin (II) mordant, the composition reduces to two monomeric and two dimeric forms, while with of iron (II) and copper (II), the extract is supplemented by several isomeric forms, including trimeric ones. The minor peaks at m/z 865 [M−H]⁻ remain unidentified, presumably due to type-A trimers.

The absence or extremely low content of ellagic acid in fibers dyed with macerate R. acetosa is attributed to the low tannic acid uptake observed in wool fibers. For instance, studies on chemically modified wool fibers confirm that the amount of tannic acid absorbed by wool does not increase significantly, even when the soaking time is extended [54].

Based on the findings presented in Figure 7, the DMSO extracts of P. erecta-dyed yarn contained high levels of procyanidins. The concentrations of monomeric and oligomeric procyanidins in the P. erecta DMSO extracts ranged from 7.2 (AL/Cu (II)) to 25.7 (AL/Sn (II)) mg g⁻¹ and from 7.2 (AL/Cu (II)) to 18.2 (AL) mg g⁻¹ per yarn, respectively. The DMSO extract from the dye yarn of P. erecta revealed a remarkable amount of catechin and epicatechin, with levels ranging from 27.5% (AL) to 54.9% (Aq/Sn (II)) for catechin and from 6.1% (Aq/Al (III)) to 29.8% (AL/Sn (II)) for epicatechin. Apart from monomers, the composition of the extract showed a relative abundance of dimeric procyanidin B3, especially in yarns dyed with an aqueous solution and using copper (II) and iron (II) as mordants. A notable feature was associated with the presence of dimer B2 in aqueous solutions used for maceration and its absence in aqueous–alkaline solutions, where another type-A dimer with m/z 575 [M−H]⁻ was detected, regardless of whether a mordant was used or not.

According to the results shown in Figure 8, the skein of yarn extracts obtained from the dye through the maceration of R. acetosa displayed low levels of individual procyanidins, with DMSO extract concentrations ranging from 0.4 to 13.6 mg g⁻¹. The concentrations of monomeric and oligomeric procyanidins in the DMSO extracts of R. acetosa dyed yarn varied from 0.1 (AL/Cu (II)) to 4.1 (Aq) mg g⁻¹ and from 0.2 (AL/Sn (II)) to 6.8 (Aq/Fe (II)) mg g⁻¹ per yarn, respectively. In contrast to the yarn treated with the P. erecta maceration solution, the extracted solution from R. acetosa showed significant variation in the oligomer content, ranging from 5.5% (Aq/Sn (II)) to 84.6% (Aq/Al (III)), while the monomer content varied from 15.5% (Aq/Al (III)) to 94.5% (Aq/Sn (II)). In addition, it was noted that the highest concentration of oligomers in DMSO extracts was observed after treatment of the solution with a potassium alum mordant, both with subsequent treatment in non-alkaline (84.6%) and alkaline solutions (80.2%), as well as in the alkali-free dye system without mordant (70.1%) and their combination with a copper (II)-based mordant (78.7%). It is crucial to mention that particularly low procyanidin values were found when using copper (II) as a mordant in both aqueous and in aqueous–alkaline solutions, measuring 59.3 ± 21.5 and 40.2 ± 18.4 mg 100 g⁻¹, respectively. In this context, copper (II) can be considered as an effective binder for attaching procyanidins to the amino groups, carboxyl groups, and alcohol groups of the fiber protein.

The result from treatment with aluminum (III) are similar to the procyanidin content obtained using copper (II) as the mordant. Potassium tartrate serves as a complexing agent with a peptide groups and functions well as a ligand for aluminum when combined with the potassium alum reagent used in the mordanting process. The total procyanidin values for yarn extracts, when mordanting with copper (II) and aluminum (III), were 16.37 ± 0.46 (Aq), 14.34 ± 0.54 (AL), and 15.94 ± 0.66 (Aq), 14.03 ± 0.80 (AL) mg/g of wool, respectively. This similarity in the composition and content of procyanidins indicates that the color differences are largely determined by the mordant used.

Epicatechin and oligomers of the epicatechin units (B2, C1) predominate in the DMSO extract obtained from yarn dyed with an aqueous solution of R. acetosa. However, treatment in alkaline macerate shows that the yarn extracts predominantly contain catechin and oligomers of catechin units (B3). These differences in procyanidin composition correspond to the initial composition of the rhizome maceration (Figure 8) and are maintained with different mordanting methods. In contrast to maceration in water, the prolonged exposure of rhizomes to alkaline conditions contributed to an increase in the content of catechin and its oligomers in the macerate but did not increase the total procyanidin content (7.2 ± 0.7 mg g⁻¹ DM), which was importantly higher in aqueous maceration (73.3 ± 9.7 mg g⁻¹ DM). These results align with the pH dependency of dimers and monomers degradation reported by Zhu et al. [55], who tested a series of sodium phosphate buffers (60 mM) with pH values ranging from 5.0 to 9.0. In alkaline conditions, (-)-epicatechin decomposes and epimerizes to catechin, resulting in interconversion products predominating in the R. acetosa dye solution. Despite the differences in the isomeric forms of procyanidins between dyeing solutions, the characteristic values of the tones of yarn dyed with them were very similar (Table 5, without mordant). In the case of P. erecta, the epimerization of catechin and epicatechin towards catechin is not observed; however, the transformation of dimers B2 and B3 and trimer C1 into one of the procyanidin forms detected in the alkaline dye solution nevertheless occurs, forming dimer-5 (m/z 577 [M-H]⁻), dimer-7 (m/z 575 [M-H]⁻), and dimer-6 (m/z 577 [M-H]⁻}.

4. Discussion

The composition and content of tannins represented in plants are diverse and provide various shades of fabric coloring [56]. Procyanidins or condensed tannins, which are flavonoid polyphenols, act as dyes or auxiliaries in textile dyeing [57,58]. Studies on the use of condensed tannins in wool dyeing are few. Still, they indicate the influence of temperature and pH on the formation of shades, which is explained by the process of monomer cyclization, acid-catalyzed polymerization, and oxidation of oligomeric forms [59]. Catechin and epicatechin are considered precursors of procyanidins in plants [60], the presence of which was detected in our study with R. acetosa and P. erecta dye solutions. During the study, it was found that the procyanidins present in P. erecta and R. acetosa dyeing solutions contribute to the formation of color on wool fibers. Upon treatment with mordants, it became clear that procyanidins form strong complexes with Al (III) [61] and Cu (II) but significantly weaker complexes with Fe (II) and Sn (II) [62]. Given that the strong action of HCl disrupts the dye–metal complex, allowing the chromophores to be extracted into solvents, hydrolysis at elevated temperatures is the most widely recommended procedure for dye extraction [63]. However, acid-based extraction can cause excessive hydrolysis, decarboxylation, and the cleavage of glycosidic bonds in chromophores, resulting in a loss of the relationship between the identified compound and the source of the dye [64]. Polar aprotic solvents such as pyridine, DMF, and DMSO are used for gentle extraction [63]. When extracting wool samples, we found that the use of acid was not necessary to separate procyanidins from the fibers and that DMSO treatment was sufficient to extract the chromophores. This method made it possible to compare the content of the obtained procyanidins with the content obtained from plant rhizomes without losing their original structure.

Curing the rhizomes in water with wood ash and heating, through a fermentation process, could yield dyes that produced red or rusty colors, an approach employed in Iron Age northern Europe [65]. Tests on birch wood ash showed that the fermentation of tannins is accompanied by a change in the pH of the solution from 10 to neutral and then acidic (pH 6.0). The observed changes and pH ranges are consistent with our tests using different mixed deciduous trees as ash sources in the alkaline fermentation of rhizomes with a similar ash-to-water ratio (1:7 by volume, v/v). Finnish researchers, testing a dyeing method with Rhamnus frangula (bark), Betula pendula (bark), and Potentilla erecta (roots), obtained red-toned wool yarn threads, wherein ellagic acid and its equivalents were noted as the main dyes in the case of tormentil. The dyeing result obtained with tormentil (P. erecta) rhizomes (L* = 37.09 a* = 25.87 b* = 22.17; color “Lusty”) surpasses the dyeing we achieved (chroma diff. 20.06), which can be explained by the shorter exposure time of the yarn in the dyeing solution (48 h) compared to that used by the Finnish researchers (two weeks at room temperature). The observed color contrast suggests that the significant factor is the duration of the yarn’s exposure in the alkaline extraction dyeing solution, which saturates the wool fibers with procyanidins more intensively than the two-day aged and following two-hour thermal post-treatment used by us.

The results of the dyeing experiments confirm that the color tones described in the written ethnographic sources and the dye plants used to obtain them are essentially accurate. Meanwhile, the experiments also confirm that the range of color tones, the name of which is associated with the concept of “red”, differs from the color names used today. In contemporary use, the word “red” is applied to tones where the red dye is represented much more clearly and intensely. Admittedly, in the climatic zone of North-Eastern Europe, it is difficult to obtain a bright red color with local natural materials. Perhaps this was the reason why, in traditional peasant culture, the spectrum of color tones that was recognized as corresponding to the color red expanded. Even the presence of a minute red nuance in a particular tone was sufficient for it to be perceived and used as a red color and to be named red. The researcher of Latvian clothing history Ieva Pīgozne, in her study, which has been based on the analysis of folklore texts and archaeological evidence to explore the meaning of colors in ancient Latvian clothing, finds that the use of red had both symbolic and magical connotations [66] (p. 109). Hence, the acquisition of reddish tones was of importance. Ancient dyers with profound knowledge of the local nature knew various dyeing methods that enabled them to obtain tones of this significant color. As the studies presented in this article have demonstrated, the use of alkali was one of them. This is also confirmed by other dyeing experiments conducted outside the scope of this study. For example, in 2021, dyeing experiments were conducted using alkali, where the underbark or cambium layer (Latvian: gremzdi) of the birch (Latvian: bērzs) Betula pendula was soaked in it. Likewise, in 2023, dyeing in a similar way was tested with the bark of the bird cherry (Latvian: ieva) Prunus padus. The results of the dyeing are shown in Appendix A (Figure A1 and Figure A2) The comparison of all the tones obtained from plants that contain tannins [6,7,67,68] with the help of alkali reveals that the range of tones is characterized by mutual similarity—it can be observed in Figure A3.

Namely, tannins react similarly to alkali, giving rosy (with alum or tin salt), dark grey and black tones (with iron sulfate), as well as reddish-brown tones (with copper sulfate). A comparison of the results of dyeing experiments with texts found in ethnographic sources yields the conclusion that in the rustic environment, reddish-brown tones, as well as brown with a red tint, could be used as the equivalent of red (color tones designated by the word “red”).

The knowledge acquired during the research can be applied in textile dyeing today, when the use of natural dyes is gaining increasing popularity due to ecological and artistically aesthetic considerations. By understanding the processes that unfold during dyeing, it is possible to employ them to achieve a specific, planned result.

5. Conclusions

Although the ethnographic sources do not contain direct indications of the dyeing method used when dyeing with P. erecta and R. acetosa, it can be stated with a relatively high degree of certainty that the dye extract was prepared by pre-macerating the dye plants in a strong alkaline solution. In rural areas, a readily available raw material—alkali obtained from deciduous wood ash—could serve as a means of fermenting plants to produce red dye. The dye solution, obtained via aqueous extraction, mainly gives yellow-brown and greenish-brown tones, except for R. acetosa, which is mordanted with copper sulfate. The use of mordants may have expanded the range of shades previously denoted by the word “red” and the use of which, like other shades of red, could have a symbolic meaning.

The results indicated that a higher yield of rhizome extraction was achieved through the alkaline–aqueous maceration of P. erecta (420 ± 21 mg g⁻¹ DW) and the water maceration of R. acetosa (92 ± 4 mg g⁻¹ DW). FTIR studies demonstrate that the purified dye solution extracts contain procyanidins with properties resembling those of commercially available materials. The chromatographic composition of procyanidins isolated from the yarn aligns with the procyanidin profile of the dye solution, influenced somewhat by the mordants used to modify the fiber. Analyzing procyanidins shows that they can be quantitatively extracted using DMSO. The external standard method was applied to quantify and assess the procyanidin content in the samples, leading to the identification of catechin, epicatechin, A2, B2, B3, C1, and C2, in addition to four unidentified dimers with m/z 577 [M−H]⁻, two dimers with m/z 575 [M−H]⁻, three trimers with m/z 863 [M−H]⁻, and two trimers with m/z 865 [M−H]⁻ detected. Procyanidin B1 was not detected in any of the extracts. Results from RP-UPLC-MS demonstrated that greater binding of procyanidins to the fiber occurred when the dyed yarn was mordanted with copper (II) and aluminum (III). In these cases, the lowest procyanidin extract was obtained from the dyed yarn of both R. acetosa (0.40 ± 0.22 and 0.63 ± 0.28 mg g⁻¹ per wool) and P. erecta (15.94 ± 0.66 and 14.03 ± 0.88 mg g⁻¹ per wool), when using aqueous and alkaline–aqueous macerate solutions. One degradation product of hydrolyzable tannins, specifically ellagic acid, was isolated from the DMSO extract of P. erecta-dyed yarn, indicating the presence of ellagitannins or their derivatives. The most vibrant yarn color, varying from red, was achieved with R. acetosa using copper (II) as a mordant and with P. erecta using tin (II) as a mordant, which was previously treated with a dye solution from the alkaline–aqueous maceration. This indicates a significantly higher sorption volume of procyanidins on wool fibers, which, in synergy with hydrolyzable tannins, created a more intense tone both before and after mordant treatment. The results obtained from dye experiments revealed the condensed procyanidin content of the analyzed yarn samples and supported the hypothesis that the monomers, dimers, and trimers form the basis for color formation.