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I have a challenge. I recently bought a cotton/polyester coat with the intention of bleaching it to near-white. To my surprise, normal bleach with sodium hypochlorite had very little effect. It changed the color from light brown to mustard-yellow-ish, even after two soakings in a 30% mixture using water and 5% sodium hypochlorite for about 10 hours each.

My second attempt was better. I put a test piece of fabric in a solution and boiled it in the microwave. It made it even lighter, but still far away from my desired near-white (white-yellow or offwhite is what I hope to achieve).

I also tried to soak it in white spirit, with a small added extra bleaching effect.

Now, using common household chemicals, how can I achieve the desired bleaching? Can I increase the effect of the chlorine? Can I use peroxide, ammonia, or any other chemical to strip the fabric of its color? I'm willing to risk to have the fabric destroyed in the process.

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closed as too broad by Mithoron, airhuff, Jan, bon, Todd Minehardt Oct 18 '17 at 13:51

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ Forget it. The colour is obviously not very sensitive to oxidation. I am quite sure you will irreversibly damage the fabric. Soaking for hours in hypochlorite at elevated temperature is not nice. And i hope you DO NOT INTEND TO USE A POLYESTER COAT AS A LAB COAT for chemistry! Sorry for the shouting. $\endgroup$ – Karl Jan 11 '17 at 16:42
  • $\begingroup$ Not at all, it's for a costume party. The coat is made from thick material, almost like felt. As I said, I've had some success soaking a test sample in a bleach solution for a few hours, and more success at an elevated temperature. But since I'm getting to a point where the effect is waning, I've come here for expert advice. $\endgroup$ – Pedery Jan 11 '17 at 17:28
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    $\begingroup$ This isn't an entirely chemistry question, given that most cotton-polyester blends are actually cotton threads wrapped around a polyester core for maximum comfort and stability. It could be that the bleach is acting on the cotton surface layer, and has no effect on the core polyester, giving you a mustard yellow color (white cotton wrapped around brown = yellow) $\endgroup$ – Edison Hua Jan 11 '17 at 22:07
  • $\begingroup$ Here's an excellent article about the various chemicals that are commonly used for color removal and bleaching: pburch.net/dyeing/FAQ/discharge_chemicals.shtml $\endgroup$ – Pedery Jan 15 '17 at 3:01
  • $\begingroup$ Why not just paint the coat? Fabric paint or acrylic paint might work. You could use a spray bottle and do very thin layers. After it's dried a good washing would get rid of any stiffness. $\endgroup$ – Dbs Oct 17 '17 at 21:16
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The yellowish mustard color I would have to say was caused by your efforts to de-color this polyester, polyester is a decently strong polymer and thus is resistant to many forms of chemical tamper, and in all effects the bleach is damaging the fabric and leaving behind that yellow color, I would suggest using Sulfur Dioxide if you can get your hands on it as that can bleach polyester, you should be left with a white translucent fabric if the bleach hasn't already damaged the fabric too terribly.

Sulfur Dioxide part is iffy, you may choose to disregard that.

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You can't bleach it entirely since some of the color has actually migrated inside the polyester thread.

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  • $\begingroup$ But what if I mix common household bleach and ammonia? Then I'll get chlorine gas, which can strip color more or less completely, right? $\endgroup$ – Pedery Jan 11 '17 at 16:00
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    $\begingroup$ That won't work and the reaction products are extremely dangerous to your health. Do not try that. $\endgroup$ – MaxW Jan 11 '17 at 16:08
  • $\begingroup$ I'm well aware of the dangers, but very interested in any possible results. $\endgroup$ – Pedery Jan 11 '17 at 16:20
  • $\begingroup$ You will damage not only your health, but also the coat. One go in the washing machine afterwards and you can use it as a see-through negligee. $\endgroup$ – Karl Jan 11 '17 at 16:49
  • $\begingroup$ That's actually a lot better progress than I've been getting so far :) I'm just skeptical to people saying "it can't be done". $\endgroup$ – Pedery Jan 11 '17 at 17:25
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NEVER ever mix chlorine bleach with ammonia. You will get chloramine gas that is deadly if breathed in concentrated amounts, as it eats holes in your lungs that would leave you with permanent lung damage at best or give a very painful death at worst. Don't do it, whatsoever. This coat is not worth your life or wellbeing. https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprd3793292.pdf That being said, probably you won't be able to get a total white color from bleaching. Polyester is a synthetic fiber, and is resistant to dying and bleaching. One of my chemistry professors tried tie-dying her polyester lab coat, and it came out in pastel colors instead of the brights she wanted. And just a couple days ago, I tried using chlorine bleach with water to create an acid-wash affect on a navy blue dress that was a cotton/polyester blend. I soaked it in the solution for 6 hours, and it came out a sage green. Probably your best bet is just buying a white coat and saving the hassle.

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  • $\begingroup$ It wasn't me that downvoted, but don't you agree that part of the point of this forum is to actually learn something. Even if it's not worth the hassle, we're all building knowledge in the process ;) $\endgroup$ – Pedery Aug 17 '17 at 7:58

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