Images of GJM-492 with increasing amounts of RBBR, immobilised to cellulose layers (above the acid form, below the corresponding base form) and to T-shirts (left spot is the acid form, right spot is the corresponding base form) using different weight ratios of GJM-492 and RBBR in the immobilisation procedure, namely 1:0, 1:1, 1:2, 1:4 and 1:8 from left to right.