On Saturday, I will be going to a workshop with Shelley Brenner Baird with several of my Miami Valley Art Work Network cronies. We are going to be working with thermofax prints using thickened dyes...in order to do this we needed fabric prepared for dyeing.
I bought bolt of 100 meters of PFD (prepared for dyeing) Pimatex as this would give us the best price and we almost had 100 meters spoken for. Since one of our members who is going to the workshop couldn't be there to pick up her fabric, I pre-soaked it with soda ash for her today along with mine.
As I was speaking with a number of quilters, I discovered that there was quite a bit of confusion on dyeing.
I have been asked "If it's PFD, then why do I have to soak it?" PFD (Prepared for Dyeing) only means it doesn't have any of the UV retardants, sizing, and other finishes which are regularly put on fabric at the company in order to make it last better, stay crisper, take the print better, blah blah blah. You can prep fabric which has been printed for taking fiber reactive dyes by heating a pot of muratic acid and synthrapol to remove the finish, but I really hate doing that. Some people just dye without doing it, and this will make the end product not as colorfast as going through whole process.
The steps are that you wash the fabric in hot water and synthrapol and a little soda ash (like 2 T) first. This removes any oils or stuff which may have gotten on the fabric at the factory or at the distributors. This is called "scouring" but you might just as well as thinking of it as washing.
Then, the material is soaked in the soda ash bath and removed and allowed to dry without rinsing, although it can be used wet. Soda ash is sodium carbonate... notice NOT sodium bicarbonate or baking soda. It has a lot more alkalinity than baking soda. It is also not washing soda...although washing soda can be used, it isn't as strong as sodium carbonate and so you use more of it. In addition, sometimes washing soda has had optical brighteners added to it to make your laundry brighter. An inexpensive source for smaller amounts is found in pool/spa stores as it is used to raise the pH of water.
The Soda ash makes the dye bond better to the fibers...it raises the pH (it is very alkaline...and thus is why one brand is pH Up and sold in pool stores to increase the pH of the water of the pool) and actually causes the plant fibers to "attack" the dyes.
It is important if you are prepping the fabric for dyeing NOT to rinse the fabric or get water on it after soaking it in Soda ash...as it will defeat the purpose. The soaking in soda ash is done in a tub or a bucket...because you really don't want the extremely alkaline substance to get into your washer and dryer. One issue with alkalines is that it actually causes some colors to fade....NOT what I want...in fact, I'm still trying to figure out what my husband has started using in the wash as I now have spotty nightgowns which were once peach....Using the soda ash makes the dye more colorfast as well as a real dye, not using soda ash can mean that it is just stained and won't work well.
I'll also note that using commercially printed fabrics for over-dyeing without removing the finish and not using soda ash can result in muckier, or muddied colors. Temperature of the water and heat setting also results in color variation (usually hotter temps or curing in a microwave specifically used for that--not for food or steaming the dyed fabric results in brighter, more colorfast fabrics).
Another thing which sort of boggles me is that my little group have often been excited when they hear about dyeing with Kool-aid or some of the new dyes available which are used in plastic bags. They are excited because handling the Mx dyes, or fiber-reactive dyes is dangerous. The dyes are fine and many are known carcinogens and generally just really bad for your lungs. I usually take a deep breath and say I'll look into it but I'm betting that it wasn't used on cotton.
Unfortunately, cotton and other vegetable based fibers such as linen, Rayon, and hemp, need a fiber reactive dye...Cushings dyes, acid dyes, and Kool-aid only work on protein based fibers (wool and silk).
If you are working with synthetics such as polyester, then you'll need special dyes for that...Dylon and Rit, among others, make dyes specifically for polyester.
If you look at the deck, you'll notice white spots...this is where the soda ash solution dripped off the fabric onto the deck...and dried....I've got to hose it all down tomorrow or pretend I'm homesteading in Montana and have run across some alkali flats.
Next time, I'll cut the lengths shorter to work with instead of working with a full 10 meters which is what this piece was....It fell off and got a bit dirty so now I have to cut an additional 4 1/2 meters. I wanted to make sure that the pieces I handed out were clean and ready to go.