Country or region: United States
Message: Hello Paula –
Hydrogen Peroxide is said to be ineffective as a bleach stop….I have been perusing your website to solve a problem I have with a Pier 1 seat / back cover for a director’s chair. I wanted to remove the color from the fabric, 100% cotton canvas, but chlorine bleach wouldn’t work! Anyway, I was double-checking about a bleach stop to neutralize the bleach I used and I see you still recommend Hydrogen Peroxide. Do you still? I found another resource that says it’s ineffective. It makes reference to a book by Rayna Gillman. Here’s the link: About Bleach Neutralizers, by Natasha Gilani. Let me know what you think ……Thanks. Denise
Thanks for writing, Denise, and thank you in particular for including your reference. I do still recommend the use of hydrogen peroxide for neutralizing chlorine bleach.
Rayna Gillman is mistaken, I think, and I think that Natasha Gilani could use some more authoritative sources. The only mention of peroxide in Gillman’s book reads:
“Anti-Chlor (sodium bisulfite) is the only substance that stops chlorine bleach from destroying fabric. Neither hydrogen peroxide nor vinegar (two old wive’s tales) will do the job. Anti-Chlor is available from ProChem, and a similar product is available from other dyehouses.” (Page 61 of “Create Your Own Hand-Printed Cloth: Stamp, Screen & Stencil with Everyday Objects”, 2008).
There’s no additional supporting evidence, and no reference for her assertion. I think it’s merely an error in which she conflated the effectiveness of hydrogen peroxide with that of vinegar. A larger error is her claim that sodium bisufite is the only substance that can stop damage from chlorine bleach. Dharma Trading Company’s Bleach Stop is a different chemical, sodium thiosulfate; while it is less economical than sodium bisulfite, since a larger quantity of it must be used, nobody (as far as I know) asserts that it is any less effective. I recommend Anti-Chlor over Bleach-Stop only because of the convenience and economy of being able to use a much smaller volume of the chemical; they are equally effective at preventing damage.
In my own experience, hydrogen peroxide, the ordinary 3% strength commonly sold for use as an antiseptic, is highly effective as a bleach stop. Garments on which I’ve used hydrogen peroxide as a bleach stop have survived years of heavy use by my family; when my son eventually wore one of them out, after years of frequent wear (it was a favorite of his), it was the seams that failed, not in the area of the bleached-out designs. This is in spite of the fact that the navy blue dye of that particular shirt was rather resistant to the bleach, so I had left it to bleach for considerably more time than other items. Another shirt even now continues to be worn occasionally by my husband, fourteen years after I neutralized a bleached-out design on it with hydrogen peroxide, and there is still no sign of degradation of the fabric in the bleached-out areas! (Unfortunately I don’t have any unneutralized bleached shirts for comparison.)
Now, hydrogen peroxide might not work if it has been sitting on the shelf for a long time. Hydrogen peroxide is quite reactive and will eventually go bad. If a bottle is still sealed, it may be good for up to three years after purchase, but once the seal has been broken, expect it to last no more than a year. In fact, its full effectiveness starts to decline within a month or two after the bottle has been opened, so it’s best to use a recently opened bottle for critical uses like neutralizing chlorine bleach. I don’t know how fresh my bottle was, but obviously it was fresh enough. I rinsed the bleached fabric with water, and then poured the peroxide over it.
Hydrogen peroxide is less economical than Anti-Chlor or Bleach-Stop, but it’s not unreasonable in cost. It has a real advantage, moreover; unlike either sodium bisulfite or sodium thiosulfate, it doesn’t present any risk to asthmatics. Five or ten percent of people with asthma are sensitive to sodium bisufite and are better off if they avoid exposure to it (though I imagine that using it as a bleach neutralizer would probably be safe even for people with sulfite-sensitive asthma, if they wear a respirator with an acid gas cartridge).
To compare the effectiveness of hydrogen peroxide with vinegar, for neutralizing the hypochlorite in chlorine bleach, it’s worth taking a look at the chemical reactions involved. The chemical reaction between hypochlorite (the active ingredient in chlorine bleach) and hydrogen peroxide is as follows:
OCl- + H2O2 -> Cl- + H2O + O2
It produces chloride ion, which makes sodium chloride, i.e. ordinary table salt, plus bubbles of gaseous oxygen. In contrast, the acetic acid in vinegar reacts with the hypochlorite to produce sodium acetate plus hypochlorous acid:
NaOCl + HOAc <-> NaOAc + HOCl
In the presence of acid, hypochlorous acid degrades to form chlorine gas. It is quite unlikely that a home dyer will use a large enough quantity of acid to produce lethal accumulations of chlorine gas, but the fact (as I’ve heard it) is that hypochlorous acid is even more damaging to fabric than hypochlorite, so it’s hardly an improvement. Deaths and serious injuries caused by mixing chlorine bleach with acids have all involved a much stronger acid than vinegar (a strong phosphoric acid solution used for cleaning toilets has sometimes been mixed disastrously with chlorine bleach). Chlorine bleach as supplied for home use is supplied as a mixture with extra sodium hydroxide in order to help prevent the reaction of chlorine bleach that occurs with acid.
For more information on neutralizing chlorine bleach, please see my page, “How can I neutralize the damaging effects of chlorine bleach?”.
For your canvas director’s chair seat and back, after you have washed out the chlorine bleach and used either peroxide or Anti-chlor to prevent damage from the bleach….although bleach did not work to remove the color, it is possible, though far from guaranteed, that a reducing type of color remover might work. Bleach and color removers work in a different way, so sometimes one works when the other does not. Howveer, some dyes simply cannot be removed, and it is impossible to know what dyes were used in your covers. See my page, “What chemicals can be used to remove dye?”. Alternatively, you might use the old seat and back as patterns to sew new covers from undyed cotton canvas. If a beige color will do, Pier One currently has new director’s chair covers, in “sand”, on sale on their website.
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