bleaching natural wool
Name: Kathy Hinckley
Message: Hi, Paula. Thanks for your incredible site! I'm a spinner, mainly interested in wool (and other animal fibers, e.g. mohair, alpaca), and I'd like to know how to bleach wool to pure white, or close to it. Obviously, not with chlorine bleach. ProChem has a recipe with hydrogen peroxide, but it didn't work too well (though it works great on natural ecru cotton). I've also see some references to bleaching wool with sodium hydrosulfite (Rit Color Remover; didn't work either) or thiourea dioxide. Clearly, it's possible since pure white yarns are commercially available. Do you know anything about bleaching animal fibers from natural off-white to white-white?
The fact that pure white yarns exist imply that it is possible for *some* wool to be bleached to white, but not necessarily your wool! Surely that the wool from some breeds of sheep bleaches more easily than that from others. However, I have never heard of a person whose hair could not be bleached, and so I am sure that any wool can be lightened also, though perhaps not without undesirable consequences to its texture.
It could be that your wool is protected by the natural lanolin, preventing the discharge agents from reaching the actual protein fibers. If that is the case, you need to use a detergent specifically made for this purpose, at a temperature of 165 F. (74 C) - but then, as a wool spinner. you undoubtedly know much more about that than I do. I've never tried to bleach wool, and can just share some general observations.
I believe that all methods of bleaching wool will damage the wool if used for too long a time or in too high of a concentration, so it may take you trial and error to determine how much of any whitening treatment will have the desired effect without damaging the wool too much. Have you tried a higher concentration, or longer time, or warmer room temperature, for either the hydrosulfite (Rit Color Remover) or the peroxide? You already know that chlorine bleach will just destroy wool. Two other discharge agents are thiourea dioxide, or thiox, and sodium formaldehyde sulfonxylate, also known as formusol or rongalite, but they should be similar in results to the hydrosulfite.
There is one exception to the rule of whitening correlating with potential for damage, in the form of optical whiteners. These are colorless dyes which absorb light in the ultraviolet range, and emit it as visible light, thus making fiber appear to be whiter. These are good to use on white materials, but of course should not be used before dyeing with colors. One brand is Rit's "Whitener & Brightener"; another is Uvitex BNB, available from Dharma Trading Company. Also, in some cases, sunlight alone will be sufficient as a bleach.
Posted: Saturday - April 30, 2005 at 08:04 PM