Apart from immobilising such dyes to cellulose layers, it appears logical to immobilise such indicators to materials where vinylsulfonyl dyes have way back been immobilised, namely textile materials. Accordingly, we have immobilised pH indicators and the inert dye to T-shirts, facecloths and cotton swabs. The T-shirts were coloured with GJM-492 and RBBR to enable the measurement of pH on the skin. Since the “surface pH of the skin on the forearm of a healthy adult white male” has been reported as 5.4–5.9 [25], we considered the pKa of 6.1 of the pH indicator GJM-492 appropriate. Interestingly, the pH on the skin not only is relevant for monitoring atopic and contact dermatitis [26], but also significant changes in pH on the skin to higher values were found for both male and female in the case of non-insulin dependent diabetes mellitus [27]. The fact that significant differences between male and female skin do exist has only recently been acknowledged [28]. Tests of a selected set of probands wearing the T-shirts (taking into consideration both gender and age) are in preparation.