detobias detobias
I’ve used your idle poly to dye poly velvet and have been told there is no mordant. Recently I used a competitor’s disperse dye for the color and their instructions included adding citric acid to the bath for permanence. Do you recommend that with idye poly?
thanks for this forum! Dianne 
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Jacquardmod Jacquardmod
I don't think it will hurt.  I have literally never heard this before.  I know you can remove color with base, so I guess it isn't crazy to think you can set it with acid.

I am going to ask some of my dyeing experts out there.  Disperse dyes are really different and follow different rules.  Let me see what I can dig up.  
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detobias detobias
Thanks!
I have been pleased with the permanence of the idye poly dyed velvet I have done so am surprised their answer was that it was for permanence.
Check out the new color combos I’m getting with the new technique. Dianne
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Jacquardmod Jacquardmod

So, I contacted someone with more experience with disperse dyes than I.  They are saying that it isn't really for the "permanence" it sounds liek it actually has more to do with keeping the dyes dispersed(because they are not soluble in water).  

A pH of around 5-6 is best for the "stability"of most disperse dyes. It can be achieved with citric or acetic. When we dye low energy disperse dyes on nylon or acetate in the lab, we run them "neutral", as in dye, water and 190'F. But always on polyester we run some acetic and a dispersing agent and if at 212'F we use some carrier(Dye intensifier) as well. At high temps(meaning under pressure), we skip the carrier. I have never heard that it improves the permanence (which I interpret as washfastness). Let's talk about stability...."Instability" would mean the dispersion breaks and the dye could leave spots or unlevelness. Sometimes the dyebath also includes dispersing agents, wetting agents and other necessary "snake oils" that could take the pH up or down, so setting it with some acid is needed as a precaution to maintain the stability of the dyestuffs.

 

So, if good results have been achieved without adding acid, it is probably because no high or low pH chemicals were added either and the bath pH probably has been ending up in the happy zone. Or, the dyes selected are not affected by pH highs/lows. Production situations and fabric styles can create the need for the extra care to set pH. Your customer's situations are probably more simple. So,it's not a bad idea to use some citric or a little vinegar to pose as acetic. But probably not a big deal if you don't add a lot of other chemicals that could jerk the pH.



So,  my interpretation of this is that if you haven't had streaks or spots on your fabric it might not matter much.  I am not sure it actually affects the color.  I am going to test a few colors and see if I can get better color with acid.  

Keep in mind for professional dyers in industrial settings, they are dyeing perhaps hundreds of lbs of fabric at a time.  Some of the issues that they run into don't really apply to the home dyer.  You don't need levelers and other posttreaments when you are dyeing on a small scale.  There are plenty of chemicals and additives to take your dyeing from 95% great to 99% great, but they are often bad for the environment or then require further processing/special detergents etc.  Now this sin't that, citric acid is fine to use, the question is whether we need it specifically for these dyes.  We can only tell by testing.

Sounds like it will not affect the permanence though.  

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detobias detobias
Thank you!! I will try and let you know.
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