I'll just repeat myself from that other forum:
"Every time I've tried taking a print straight from rapid fixer to selenium toner the print wound up with stains.
"Now I always wash for at least 10 minutes before selenium toning. "Washing" may consist of simply soaking in HCA (or similar product) followed by soaking in a gallon container of fresh water. Either way, it works - no more staining.
"After selenium toning I go straight to the wash. No HCA or other rinse aid.
"As I've described in other posts, my "archival" washer is a 5-gallon bucket with a recirculating aquarium pump. The length of wash time and how often I dump and refill with fresh water is determined by the number of prints I'm processing.
"Recently I added another 5-gallon bucket/aquarium pump to the lineup. Haven't put it to use yet, tho'.
"The entire mess - HCA/wash aid, prerinse container, selenium, wash buckets - all sit in the bathtub of our spare bathroom.
"In fiber and RC prints, so prepared, which I've exposed to accelerated torture testing, none has yet failed in any way after nearly six months. While that may not equate with claims for 100 or 500 years of archival existence, it does seem to indicate that only reasonable precautions are needed to produce prints that will be satisfactory."