Fig. 5(a), for Remazol Red F-3B, indicates a very
modest decrease in molar extinction coecient for
the soluble aggregate species on addition of
increasing concentrations of salt. However a much
more marked decrease is observed for the mono-
meric species.
Fig. 5(b), indicates that Procion Red MX-5B is
much more salt sensitive. The greater decrease in
molar extinction coecient suggests that mono-
meric species are being replaced by soluble aggre-
gates as the concentration of salt increases.
In the case of Procion MX-5B, the addition of
increasing concentrations of urea produces a more
dramatic increase in concentration of both mono-
mer and soluble aggregates than with Remazol
Red F-3B. Both products at the concentration of
dye used only need approximately 50 g lÿ1 of urea
to optimise the amount of disaggregation.
The study suggests that Remazol Red F-3B is
both less `salt sensitive' and less responsive to urea
than Procion MX-5B, technical features well
known to batchwise and continuous dyers of
cotton