Name: KAREN

Message: Hello! My daughter is doing a 6th grade science project on natural dyes (specifically fruit) on wool yarn premordanted with alum and cream of tartar.She insists on comparing two fruits for their lightfastness. She is REALLY excited about this and refuses to modify her project by comparing cotton vs wool with one fruit. Is it reasonable to assume that if one fruit was more acidic than the other (measured by PH paper) that it would form a stronger bond to the protein fiber?

It's certainly a reasonable hypothesis to start with, though I don't think it will prove to be correct. In science it does not matter whether your hypothesis ends up being correct or incorrect, though, as long as you ask the question and come up with an answer. 

I believe that the actual identity of the natural dyes within a fruit matters a great deal more than the actual pH. Cream of tartar is an acid, also known as tartaric acid, so you might have the acid pH anyway. It does not matter if you have plenty of acid, if the colored chemicals in the fruit have no affinity for the fiber.

Comparing a vegetable to a fruit is another idea that Kristen could consider. Most people who don't dye expect beets to be a good dye, but they are not. I think that most fruits are likely to produce better dyes than beets. 

It's good that you're using wool yarns. Too many kids do science projects trying to use fruits to dye cotton. It should work so much better with wool. This is because wool is made of a string of many different amino acids, each of which can attract different dyes, whereas cotton is made of long strings of nothing but glucose molecules, so there is little variation.

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