Safest and best way to wash an expensive yellowed white silk scarf?
Yellowed? Time to get a new white scarf.
OxyClean. gently, by hand. dissolve OxyClean [or other oxygen bleach product] in water. Stir vigorously. soak the scarf for at least 45 minutes ... may require multiple treatments. dry the scarf by placing it atop a long towel [folded over if necessary] and rolling the towel up into a cylinder
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I wash silk by hand gently in room temp water in a basin, rinse really really well and either flat or hang dry depending on how delicate it is. If hanging might distort the fabric I will dry flat. Then a coolish iron if just fingerpresing doesn’t make it smooth. A gentle soap like woolite is best, don’t use too cold or too hot water. I don’t ever dry clean anything, dry cleaning chemicals are incredibly toxic and as someone who has sewn with recycled materials for decades I can tell you that dry cleaning fluid can leave LOTS of debris on garments. They may look clean and pressed but when I wash them the water gets totally gross, I mean TOTALLY GROSS. Sometimes I’d have to wash things multiple times to get all the dry cleaning gunk out of the fabric. Silk is a protien (produced by animal) fiber same as wool, so soaps meant for wool are fine for silk. Scarves are typically just all silk, if you have a structured garment like a jacket or blouse that has added fiber/fabric washing will typically distort the garment. In my life, if it has to be dry cleaned, I won’t wear it, not after what I’ve seen dry cleaning leaves on garments. If the yellowing is soiling on the scarf, that is one thing. If it is actually discoloration of the silk, you may not be able to get it out. Very old silk can discolor like that. It is easy to add color with dyes, for protien fibers I like Procion Acid Dyes, used as directed.