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The problem: eating yellow curry with naan and no spoon for the first time resulted in a wonderful dinner but some permanent yellow stain on my cotton shirt. I assume it's coming at least in part from the curcumin from turmeric.

I've had some success removing bleach-resistant stains with household ~3% hydrogen peroxide. However that's surprisingly difficult to find where I live.

So I stopped by a chemistry supply shop, and they handed me a plastic bottle of 35% $\ce{H2O2}$ solution, specific gravity 1.196.

The Chinese writing on the label are common sense safety instructions (store away from light, not safe for food preparation, etc.).

Unlike household peroxide, and like some kinds of oxidizes in spacecraft (Does the Soyuz spacecraft use chemically stabilized hydrogen peroxide (H₂O₂) to remain ISS-dockable for 200+ days?) the does not appear that there are any stabilizers in the solution.

Question: How can I safely dilute to 3%, and best store after opening this 35% hydrogen peroxide solution?

I plan to dilute enough for my present needs, and try to just screw the cap back on the rest of the bottle, but maybe there's more things to consider?

Click images for full size:

35% hydrogen peroxide H2O2 cotton shirt stained by yellow curry

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    $\begingroup$ To the close voter, how might "How can I safely dilute to 3%, and best store after opening this 35% hydrogen peroxide solution?" require clarity? Why not add a comment and highlight what part isn't clear? $\endgroup$
    – uhoh
    Mar 15, 2023 at 14:04
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    $\begingroup$ @uhoh, Oxygen bleaches only work in alkaline medium. Curry stain is a two pronged problem. You have oil and oil has dissolved curcuminoids from turmeric. First get rid oil by letting only dishwashing liquid on the stain overnight. After that rub that stain with lemon and keep washing the stain under warm water. Let sunlight work on it and it should be gone. Getting rid of oil is more important. $\endgroup$
    – AChem
    Mar 15, 2023 at 14:39
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    $\begingroup$ I have meant general usual precautions for manipulation with potentially harmful chemicals. Yes, it can pressurize the bottle. But it IS usually stabilized, AFAIK. $\endgroup$
    – Poutnik
    Mar 15, 2023 at 16:16
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    $\begingroup$ @AChem your stain removal tutorial worked like a charm! :-) $\endgroup$
    – uhoh
    Jun 11, 2023 at 3:37
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    $\begingroup$ @uhoh, Glad to know my proposed stain removing chemistry worked :-) I used to do these sun "bleaching" experiments during school days. $\endgroup$
    – AChem
    Jun 11, 2023 at 3:56

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