I never clean the stantions with water, soap or any detergent – Only liquid lube.
Let the crud dry and brush off with a soft paint brush (tape the metal bit that holds the brush hairs to stop stantion scratch). Get some PTFE liquid lube and apply liberally to the stantions (Preferably with the wheel off and rag over brake calipers), make sure there is loads of PTFE Lube around the seals and compress the fork about 2". Any bits of crud from the seal will lift with the lube. Wipe eoff crud and excess and re lube lightly.
Job Done!
I use this method for general cleaning too, any cleaner will strip / wash out lube and cause accelerated wear.