Name: Mrs. May

Country or region: Hawaii, USA

Message: This is not a dye question but more of a resiliency question about fibers.  I am a knitter married to a doctor and as such I would like to knit my husband a gift of microbes for his office (example can be seen here and here).  Only issue is that anything that goes to his work needs be bleach-able.  I would love to know which fiber you would recommend for such a project.

Presently I am thinking acrylic because the stuff seems  indestructible but I am questioning that now.  I know all fibers will break down eventually with bleach so it is really question of which one will hold up the best for the longest. 

The best fibers for resisting damage from hypochlorite bleach (which is what is in household bleach) are 100% cellulose fibers, such as cotton, linen, or hemp. The worst are synthetic fibers such as nylon or spandex, and protein-based fibers such as silk or wool, all of which will dissolve in bleach. Other synthetic fibers such as polyester and acrylic tend to be damaged and permanently discolored by exposure to bleach. Check the care instructions in the label on the yarn; you will probably see a warning against using bleach on polyester or acrylic. 

I recommend that you use yarn made from 100% cotton fiber, though linen or hemp would be just as good. Bamboo and other forms of rayon will resist bleach, but their fibers become weak and breakable when wet, so they're not as ideal for your project.

In a related question, what dyes will stay bright in spite of bleaching? If you buy pre-dyed yarn, there is no way to predict which dyes will discharge with bleach, and which will resist bleach and retain their color. We know which types of dye are more bleach-resistant, but we never know what dyes have been used on commercially dyed yarn or fabric. Before investing in a lot of dyed yarn, it may be possible for you to take a tiny snip of the yarn out to your car for testing, in which case a Clorox Bleach Pen makes an ideal portable tester. If you're buying from a specialty yarn store, ask if they will give you a short sample to test.

Cotton is extremely easy to dye, so, if you find that your colors become too bleached-out and boring, you can recolor your microbes at any point. The easiest dye to use for this purpose is a tie-dyeing kit, as long as it's not made by Rit, whose tie-dye kits contain inferior dyes. For dyeing solid colors, Rit dye will work, too, but only as long as you want all parts of your creation to be dyed the same color; a good tie-dye kit allows you to paint different colors on different parts. The dye in a good tie-dyeing kit also stays bright through many more rounds of laundering, though they might not be any more bleach-resistant. There are more bleach-resistant dyes that you can use, as well as certain fabric paints, but that will be another question.

By the way, I love this project. My teenaged sons have been very enthusiastic about the plush giant microbes at Think Geek, collecting them as birthday presents, and taking them to school to amuse their friends. The more embarrassingly transmitted microbes, such as HIV or Herpes simplex, are the most popular for the older teens (they like to toss them at one another and say, "I just gave you ___!"). Adding somewhat biologically-inappropriate eyes makes them "cute", which increases their popularity with kids of all ages. Consider using some of the moving "googly eyes" that crafts and sewing stores sell.


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