As a point of awareness- Biz is alive & well. I use & have used it for all of my heirloom sewing & all hand crocheted clothing items made for me by my mom & that I made for other girls. Available in Walmart.
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I used RetroClean on a vintage dresser scarf I bought at an antique shop recently. I thought the crocheted lace was taupe and after soaking in the sun with RC, found out it was light blue. The fabric went from smokers yellow to a linen white. WOW. This stuff is amazing. I ordered it online.

Biz is still available. It works great . Article may need to soak for days. It does not harm fabric. Our local textile museum uses it on antique linens .