*2.5. Process Tests*

Coated stainless steel pieces were placed on process surfaces within three breweries for a period of three months. Figure 1 shows an example of samples in location. Details of the location of test pieces in each brewery are given in Table 2. There was no special provision of lighting for the photocatalytic coatings; the process test took place under the usual brewery conditions of lighting, with coupons receiving varying amounts of light depending on their position in each machine. Furthermore, all samples underwent the normal process conditions and cleaning regimes used in each brewery which included acid and alkaline cleaning chemicals such as acetic acid and sodium hydroxide, ethanol, steam and mechanical brushing. For each coating, two replicates were used in each of the breweries. Additionally, two replicates were retained as controls and were kept in the dark for the same period. After three months, each replicate was cut into six sections. The mechanical durability, photocatalytic activity and wettability were evaluated each on two of these sections.

**Figure 1.** Samples in location at Brewery B.

**Table 2.** Coatings evaluated in process tests (for a period of three months).


1 Filler table of beer canning machine; 2 Seamer of beer canning machine; 3 Filler table of a water and soft drinks PET line, inclined 10°.
