Having used Jacquard acid dyes for a while, I wanted to understand more about the dyes beyond the color choices. I have read about the acid dyes in a few sources. below is one of the explanations.  What does it mean in plain English for non-chemist? 

Chemically acid dyes are based on azo, anthraquinone, triphenylmethane Cu-phthalocyanin chromophoric systems which are water soluble due to presence of up to four sulphonic acid groups. These dyes are applied mainly to polyamide and wool. They are also used for silk and some modified acrylic fibres. Acid dyes exhibit little affinity for cellulose and polyester fibre. The most common chemicals and auxiliaries used during dyeing with acid dyes are as follows:

Sodium sulphatesodium acetate and ammonium sulphate.
•pH regulators: acetic, formic and sulphuric acid, but also ammonium salts and phosphoric acid salts.
•Levelling agents, mainly cationic compounds such as ethoxylated fatty amines.
•After-treatment agents such as formaldehyde condensates with aromatic sulphonic acids.


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Jacquardmod Jacquardmod
"azo, anthraquinone, triphenylmethane Cu-phthalocyanin chromophoric systems"  This is the "backbone" of the acid dye.  This just says that this is the type of structure that the chromofore is attached to.  The Chromofore is the part of the chemical that produces the color by reflecting visible light.  So basically, this system is the one that is used and different chromofores are added to make the different colors.  

The 4 sulfonic acid groups mean that it is soluble in water, which is the way most of us dye things.  There are solvent dyes as well, but they are more for industrial dyeing and dyeing weird materials.  These sulfonic groups are negatively charged, which is one reason our product Color Magnet works so well with acid dyes. In fact you can use acid dyes acid dyes on both polyester or cotton is you use it with color magnet and the background won't pick up any color.

  Acid dyes create Ionic bonds with the fiber which means instead of the reactive bonds that Procion dyes make, they are negatively attracted to positive charges on amino acids(protein fibers).  Cotton and plant fibers have much fewer positive charges(when acidified with citric or acetic acid), so that is one reason acid dyes barely work on cotton.  Of course, Procion dyes can be made to work like acid dyes if you add acid to the pot.

It says these dyes are applied to polyaminde and wool.  Polyamide is Nylon.  So yes that is correct, and of course people use them on silk and other protein fibers too like animal hair.  The funny thing about nylon is that if you look at it, the chemical structure very close to that of a protein.  In fact notice the chemical name of nylon Polyamide.  Well amino acids which make up proteins, are part amine groups and part caboxylic acids.  So they are both base and acid.  So when you put them together in a chain, they make amide bonds.  Amino + Carboxylic acid = Amide bonds.  A chain of amide bonds is a Polyamide.  Interesting. 

Sodium Sulphate is a dyers salt.  Regular salt helps too.  Those 3 listed chemicals just help to push the dye onto the fiber the way any salt does.  

pH regulators are just the acids that put the fiber in the right electronic state to accept the dye.  IF you use a base, the fiber has barely any affinity for the dye.  If you use an acid the fiber is more positively charged and accepts the negative acid dye very easily.  That is why we use acid.  

Leveling cationic agents are positively charged agents that keep the dye from being dyed unevenly and keep the dye from going on too fast.  These are not really important unless you are doing huge industrial dyeing in a giant container.  Acid dyes are in general good leveling dyes compared to procion and other reactive dyes, so leveling agents are usually unnecessary.

The after treatment is to prevent bleeding and push the unfixed dye out of the fabric and flush it out.  Those can be nasty, so it is better to use a detergent like Synthrapol or our SolarFast wash, which grabs the dye and washes it down the drain and gets the excess dye out.  These are much safer, but require more rinsing.  In industrial settings they want the dye out in a single wash, so this is how they do it.  

Does that make sense?

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