Fig. 9

Colour (A), yellowing (B) and gloss (C) of the aged plaster plate surfaces before and after the PE-PAM₁₅ SAGs cleaning trials. A no significant colour change observed above the minimum noticeable difference (ΔE₀₀ ≈ 1) with the exception of the cold pressed linseed oil coating. B Soiling increased the yellowness of all plates, while the PE-PAM₁₅ cleaning tests slightly reduced it, and (C) Contact with the PE-PAM₁₅ gels slightly increased gloss of all surfaces, although all samples remained matt (< 10 GU)