Soda Ash - The Basics

• Pool supply shops are a great place to buy. They call it 'pH Up'. 
• It irritates my skin - taken care of by using protective gloves 
• When dissolving, if you get it wet too slowly, it will form a brick that takes a l-oo-ng (long) time to dissolve. Just be sure to be swishing it a bit while adding water. 
• While I've figured much of what works for me in this messy business of fabric dyeing, how much soda ash to add is still a mystery. Some say you have to get the bath up to a pH over 10. BUT since I'm certain of this, take this with a grain of salt. (Not literally)
• Some techniques rely on pre-soaking in soda ash water. 
• Others do better adding the soda ash as a final process step. 
• How to know? IF swishing all the fabric together in the dye bath would ruin the outcome, then you do a pre-soak. IF you want the smoothest color possible - then do NOT pre-soak. 
• IF you want mottled BUT with kinda smooth transitions, then do soda ash after. 
• For a pre-soak, probably 30 minutes is good (if it's thick fabric, then longer is maybe safer). 

For AFTER, it's much more complicated.

• First, don't add the soda ash water directly over the fabric in your dye vat. AND, add it gradually. 
• One way: push the fabric to the side and add 1/4 of the soda ash water, swish into the dye bath, then swoosh the fabric through the dye bath thoroughly. Repeat 2 or 3 times. Swish really well for at least 20 minutes. 
• Then, it soaks for a while. I found 2 hours is better than 1 hour and maybe long enough. BUT, it's OK to go much longer if your life requests this -- overnight is OK. 

Preparing the soda ash water OR how much to use

• I don't have notes on how much soda ash to use. Sorry. 
• Some say to use 1 teaspoon of soda ash for every cup of water in the dye bath. SO, if you'll have 1 gallon water in the FINAL dye bath (including what is used to add the soda ash), this is 16 cups. You'd dissolve the 16 teaspoons in a cup or two of very warm water ahead of time. 
• 16 teaspoons is bit more than 5 Tablespoons. Or 1/3 cup. 
• Some recommendations end up with double or quadruple this amount. 
• Vicki Walsh did an experiment and her numbers are similar to mine. She went with about double in my example. But then she did round down a bit. 
• See, this is real messy chemistry here --- seems no one is certain. I think the reason is it depends on the water coming out of your tap. Not all tap water has the exact same characteristics. It seems that most are good with a 'rule of thumb'. 
• Go with 1/2 cup of soda ash per final gallon of dye bath. Dissolve it in 2 cups of very warm water. 
• Some day I'll test this more thoroughly myself. I read somewhere that one expert who travels a lot to teach, finds that things come out noticeably different in some places and she concluded after some experience it was due to differences in local water chemistry. But it seems most important to not have too little; using too much is wasteful of supplies and your time.