Alum acetate experiment

My experiments usually begin with a question for which I don’t have an answer.  In this case, the question is ‘Is it better to mordant mixed cellulose and wool yarns with alum acetate or potassium alum sulfate’?.  One of  issues of which I am aware is that alum acetate raised to higher temperatures can damage the fiber.  Various sources I’ve read suggest mordanting at 110 degrees F or 120 degrees F.  There is also the question of whether neutralizing the fibers in chalk after mordanting will help the process.

So, in this not very scientific experiment, skeins of 50/50 tencel merino were mordanted in alum acetate and in 7% alum and then dyed with quebracho black.  The choice of dyes was because of a project need, not a specific selection of that dye.

I mordanted two skeins in 8% alum acetate.  The temperature was kept below 120.   The two skeins were neutralized with chalk, rinsed, and dyed.  Two skeins were dyed in quebracho black.  The pot I used had had some red in it which caused some red tinting on the skeins.  These skeins did not take much dye but the hand was really nice; not stiff at all.  I took one of these skeins and put it back in the mordant pot that I had saved and heated it.  Neutralized it in chalk again, rinsed, and dyed.  I used the same dye pot and added in the same quebracho % but there was undoubtedly dye left from the previous run.  The hand is not as nice as the first skein but it is nicer than the skein mordanted in potassium alum sulfate.  It also came out darker than the skein mordanted in alum sulfate.  This could be because of the additional dye or the mordant.  Now that I know it has to be heated, I will need to run another unscientific experiment.

Same order, just wanted to see which was darker in terms of value.

From left, alum acetate heated, alum acetate maintained at or below 120 F, potassium alum sulfate
Dyed with quebracho black




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