when i pre=wash i use my regular laundry detergent- no fabric softener- i'm removing chemicals-don't want to add any-
the (quilt-soap) is called ORVIS i think it is actually a bar and you shave some off and add to the water. how ever it comes- it is supposed to only take a little and last a long time.
i have never looked into it- i figure if my detergent is good enough for my clothes, it's good enough for fabrics too.