Abstract: Disclosed is an optical brightening process for substrates comprising or consisting of synthetic polyamide in which the optical brightener is applied to the substrate by impregnation followed by heat treatment and wherein the brightener is applied in the presence of a compound or mixture of compounds of formula I,rnh.sub.2 iwherein R is --OH, --NR.sub.1 R.sub.2 or ##STR1## X being O, S or NH, and R.sub.1 and R.sub.2 being, independently, hydrogen, C.sub.1-6 alkyl or C.sub.2-4 hydroxyalkyl,Which compounds are in free base or acid addition salt form or, when R is OH, in O-sulphonic acid form, and preparations for use in such process.

Abstract: Disclosed is a textile finishing process in which there is employed, as pH regulator, a compound or mixture of compounds of formula I, ##STR1## in which N IS 0 OR 1,P is 0 or an integer from 1 to 6,Q is 2 or 3,X is a halogen,Each ofY and Z, independently, is hydrogen or halogen, andA is hydrogen, phenyl, C.sub.1-12 alkyl, or a radical of formula (a), (b) or (c), ##STR2## WHERE R IS 1 TO 4,S is 0 or an integer from 1 to 4,X, y z and n are as defined above,With the proviso that p is other than 0 when A is hydrogen or a radical of formula (c).