We cleaned an 80/20 mainly cream carpet last week, I used Chemspec one clean powder which is woolsafe approved and after doing a few colour tests we cleaned the carpet, i missted on deodourising acid rinse afterwards as we were going to stain guard the carpet and you need to remove as much residue before applying the product, we left the carpet slightly damp and the customer was over the moon with results
the next day the customer rang me to say about eight smallish pink patches had appeared over the carpet ! after returning to see what had happened I noticed there had been a small fleck in the carpet which apparently must of had a loose dye, I cured the problem with Chemspec coffee stain remover and then rinsed out with deodouring acid rinse!! I dont think any amount of pre testing would of made a difference in this case as the dye in the flec of the carpet was realy slow in migrating and we had applied acid rinse after the clean ! Anyway with a bit of good luck and quality chemicals I was able to rectify the situation
Regards stu Clark