When I use Wisk directly on stains and let it sit for a while before going into the laundry, often it bleaches my colors where I put the Wisk. What is the cause of this?
I suspect that a couple of things may have happened here. A common mistake that consumers make when pre-treating is to leave the product on until it dries. Then the original problem can be made worse in two ways: The original stain is dissolved and now spreads out, and/or the detergent contains brighteners that are now concentrated in that spot you just pretreated. This may appear to lighten the color. Unfortunately, once these brighteners have dried, they are pretty “permanent.”
In the future, to pretreat any stain, apply the product, rub it in, wait 3–5 minutes, and then wash immediately in the warmest water recommended on the care label with detergent.