When to add the soda ash for a 100% viscose cold wash light yellow dress
  • Hi there, as per the title, I have a dress I would like to dye towards a more turquoise color. I know that: 1) it will most likely end up looking green with turquoise areas (the fabric has areas of white because the pattern is tie-dye like) and 2) I plan on using the procion mx dye since it can be used cold and since heat can damage viscose.

    So my question is, would I immerse the dress in the procion dye bath first, prep the soda ash with hot/warm water, wait for it to cool, then add it to the dye bath (removing the garment prior to adding it)? I had watched a few youtube videos and there was some variation on when to add the soda ash. I saw/assumed that hot water allows for the soda ash to dissolve better but I wasn't sure if that's the reasoning for hot water. I did see on another post that there is a 5 hour window of activity for the soda ash. I don't want to end up ruining the dress by placing it in hot water.

    As an alternative, would adding salt be a better/different option? But I'm pretty sure that the soda ash works like a fixative while the salt works as a brightener, right? I only have one shot at this and I want to make sure I'm approaching this correctly. Thank you for your help!
  • Ok, so there is a lot of fretting about why and when you add soda ash. I think this is a great question because a lot of people worry about this. It is really not such a big deal, but it is important if you want the very best possible results.

    Why not add soda ash at the very beginning? Well the answer is that you absolutely can, and most of the time it will not make a very big difference. The main worry is #1 levelling, and #2 Soda ash exhausts the dye bath and makes it less effective after 5 hours or so.

    #1 what is leveling? Procion MX dyes are cold water dyes, that means low energy dyes. Because they are much slower at attacking the fiber than a hot water dye, it means that they are more likely to give uneven dyeing than a dye done at high temperature which strikes very fast and evenly. This can be especially true if you add the soda ash before you add the fabric. As the fabric gets bunched up or even as the bottom of the fabric goes in first and the top last can make a difference on how dark the fabric gets. As some areas are exposed to the ash and dye together, the folded or bunched areas get less and will be lighter over all. If you ever see cloudiness with procion dyes where some areas are very dark and some are light, this is what is going on.

    Letting the dye get into the fabric and start the process first leads to more even or "levelled" dye when you add the soda ash 5-10 minutes after you have immersed the fabric. If you add the powder directly to the bath I recommend removing the fabric. If you pre-dissolve and add to the bath, I think you are fine leaving the fabric in and stirring.

    #2 soda ash closes off the reactive sites of the dye. Soda ash does indeed fix the dye by helping it attach to the cellulose(cotton linen and other plant based fibers). The thing is it will close those reactive sites whether the fabric is there or not. So unfortunately, the longer the soda ash and dye mingle the weaker and weaker the dye bath gets. So if you add your soda ash too soon, you are not giving yourself the total dye time that you might want. This is why it is best to presoak the shirt in soda ash rather than adding to the bottles directly. You can tie dye all day if there is no soda ash in the bottle, but would have to change it after a few hours to keep your brightest colors.

    I hope this helps. Adding soda ash immediately is not a deal breaker, but really means you need to stir even more. Hopefully, this makes teh rule make more sense instead of seeming arbitrary.