While I waited for Kris to show up, I washed and bleached the Tshirts and put them on the clothes line to bleach in the sunshine. Kris arrived with her homeschool family and we enjoyed a cup a latte together and then grabbed the t-shirts and wound buttons into the fabric for a resist. Into the indigo vat they went -- at least 3 times. Indigo doesn't require a mordant, so this was a quick job.
|My friend, Kris, and her T-shirt shopping bag, dyed in the indigo vat.|
|Kris' bag has one large hole in the bottom.|
|I have 3 small holes in the bottom of my bag and closed the gap with a braid.|
|The handles seemed long, so I knotted the ends.|
I also want to make some green and yellow T shirt bags. Some natural plant dyes require a metal salt to make the dye permanent on fabric -- that would be almost any other colour but blue. The usual metal salts for wool, silk and other protein fibers are alum (an aluminum salt) sometimes called potassium alum sulphate. It is acidic -- which is good for protein fibers. You need to simmer the fiber in the alum solution (usually at 10% wof or up to 20%). You need to be careful not to use too much alum or it will make the fibers brittle and sticky. Finer wools require less alum than silk.
But when dyeing cotton with natural dyes -- these T-shirts are 100% cotton -- we mordant with a combination mordant alum - tannin - alum (using 1/2 the necessary alum in each alum bath). That's 3 mordant baths to get cotton ready for natural dyes, if you aren't using indigo or woad for blue.
India Flint suggests that sea water contains a percentage of alum and can be used as a mordant. Nice if you live near the sea -- a local source of mordant. I live near an abandoned railway track with junk piles of old railway spikes, rail tie connectors and other rusty iron paraphenalia. I also live in the shadow of a mountain, famous for its derelict copper mines. Extracting the iron mordant from rail ties or the copper from rocks requires an acid or strong alkaline solution, which then must be neutralized before using it as a mordant on your fine fiber.
The source of tannin changes the colour of the fabric which further affects the colours of the dyes. There are plant sources of tannin as well -- galls, barks, willows, pomegranate rinds, charcoal, and other things to experiment with. There is also the possibility of using calcium in the form of whey, or calcium carbonate (also mined nearby). I haven't started to experiment on other mordants yet but its in the plans for this summer.
Have you experimented with using locally sourced metal salts to mordant your natural dyes? Tell me about your experience in the comments section.