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Home » forums » Procion MX dyes and other fiber reactive dyes

Fiber-reactive dyes with soda ash bonding with PROTEIN fibers?

I just finished a series of experiments for a magazine article on cross-dyeing, and was startled to find that many colors of Cibacron F and Pro MX dyes will dye protein fibers in an alkaline environment! Photos of my experiments can be found here: http://www.tienchiu.com/2012/05/cross-dyed-dye-samples/

This renders them useless for cross-dyeing, of course.

Can you explain why this is happening, and suggest other dyes that might work for cross-dyeing? (Except for Alter Ego dyes - way too expensive for me!)

Thanks,

Tien

By tienchiu at 2012-05-22 08:26 | Procion MX dyes and other fiber reactive dyes | login or register to post comments | previous forum topic | next forum topic

question on batching in oven?

Tien, did I understand in your article, that you batched in an oven? I have not heard of that before. Anyone else tried this? Thanks, Elizabeth

By eperry at Tue, 2012-05-22 15:56 | login or register to post comments

Yes - I used an oven to

Yes - I used an oven to increase the batching temperature. I set it at 180 degrees, let it preheat, put the material-to-be-dyed in in a heat-resistant plastic bag (ziplocks are generally OK), then turned it off. I could have left it going at 180F, but I was worried about the plastic bag melting.

Worked just fine for me, though it's more of a shortcut technique than something I would do on a regular basis.

Website: http://www.tienchiu.com
Blog: http://www.tienchiu.com/category/blog-posts

By tienchiu at Wed, 2012-05-23 22:48 | login or register to post comments

oven batching

Thanks for the info!

By eperry at Thu, 2012-05-24 16:16 | login or register to post comments

fiber reactive dyes work on wool at high pH

Fiber reactive dyes react very well with natural protein fibers, such as silk and wool, at high pH. In contrast, nylon, which can be dyed with acid dyes just like wool or silk, will not take any reactive dye at high pH. Nylon stays white, while silk and wool take at least as much color as cotton does.

The only reason we never dye wool at a high pH is because the wool tends to be badly damaged afterwards. It does take the dye quite well, but, even in the little test samples, it gets noticably fuzzy. Look at my son's 2006 science fair project, in which he compared natural and synthetic dyes on various fibers. This is the picture of the test samples for a Procion MX dye on the multi-fiber test strip:
Wool is on the bottom, rayon next, then undyeable polypropylene, then silk; cotton is fourth from the top.

We do very often dye silk at a high pH, using the exact same soda ash recipe with Procion MX or other fiber reactive dyes as we do for cotton. There is no need for added heat when using fiber reactive dyes with soda ash on silk, exactly like cotton. The colors shift slightly, that's all. The color shift is because some dyes react more quickly on silk than they do on cotton, while others do not.

Previous Dye Forum discussions have some more information on cross dyeing. See Dyeing silk/rayon blends two different colors. I wrote this:

    The textile industry calls it "reserve dyeing" when one fiber in a blended fabric is dyed a different color from another fiber in the same piece of fabric.

    There is no dye that will dye only rayon or cotton, and not dye silk at all. All fiber reactive dyes will color both silk and cellulose, when used with soda ash. All direct dyes will do the same. The intensity of the color may be lighter on silk than on rayon, but the color is always there. So, how can we ever dye only the rayon in silk/devoré, without dyeing the silk?

    In the textile industry, when dyeing cotton/wool blends, a product called a "reserving agent" is used to prevent direct dye or fiber reactive dye from staining the wool. This product is a kind of syntan, but I don't know what type. It is very possible that some sort of syntan may be included in the expensive proprietary dye fixative used in the Alter Ego dye system. ($6.50 for a tiny four-ounce bottle!) The syntan is not something I expect to be able to replicate from another source; without it, we may find some color combinations difficult to obtain.

    Some acid dyes stain rayon quite badly. When I dyed a silk/rayon devoré shawl pink with fiber reactive dyes, and then black with Lanaset Jet Black, the rayon ended up taking a lot of the black. Only the fringe really remained pink, though the hints of pink showing through here and there where I'd gone easier on the Lanaset dye looked fine. (The fringe was a total pain to deal with; I intend to avoid fringe as much as possible in the future!)

    ProChem very kindly shared with me a list of which of their Washfast Acid dyes show the least staining on cotton or rayon. The best are Flavine yellow, Sun yellow, Red, and Rhodamine Red. Bright orange is not as good, and Navy another step down. All of the other WFA dyes for which information was available are more apt to stain rayon or cotton.

    If you use Rhodamine Red on silk, be sure to use it before direct dye or fiber reactive dye, not afterwards. Rhodamine is a basic dye and will dye cotton if the cotton is first mordanted by dyeing it with direct dyes. (Yes, direct dye can actually act as a mordant for basic dyes!)

I have occasionally advised dyeing wool blends with fiber reactive dye at a pH of 8. This is a low enough pH to be less damaging to the wool, but it's high enough that you get some proper dye reaction with cotton, though obviously it is less efficient and produces a lower color yield than the same amount of dye on cotton at a pH of 10 or 11.

Pia Fish has found that dyeing silk with citric acid and Procion MX dyes produces much less color shift, as compared to the same dye on cotton with soda ash, than dyeing silk with the same dye and soda ash.

The color shift with soda ash might be your best answer. It cries out for a systematic study to see which of the pure Procion MX dyes produce a most intense color on silk with soda ash than they do on cotton with soda ash. For example, yellow MX-G seems much stronger on silk than it does on cotton, relative to a mixture of the two blues turquoise MX-G and blue MX-G; the same blend of these three dyes that produces aqua on cotton, produces emerald green on silk. Dharma says that their "#18 deep purple" mixture dyes rayon purple while dyeing silk a contrasting shade of raspberry. Different black MX mixtures produce olive green or maroon on silk, while they produce black on cotton or rayon. We should have more information about different color shifts somewhere. If not, we need to make a chart of it.

There is probably some color shift between silk and wool, though not as much as that between silk and cotton, since there is more chemical similarity between silk and wool. There is usually a color shift for any pre-mixed dye when it is used on a different fiber.

-Paula

By pburch at Tue, 2012-05-22 09:49 | login or register to post comments

Thanks, Paula! This is treme

Thanks, Paula! This is tremendously helpful.

Do you know what the chemical reaction is with fiber-reactive dyes on wool in an alkaline bath, as opposed to an acid one? I'm just wondering if the bond is the ionic (I think) acid bond or whether it's a true fiber-reactive covalent bond. Curious for wash and lightfastness reasons.

Tien

Website: http://www.tienchiu.com
Blog: http://www.tienchiu.com/category/blog-posts

By tienchiu at Tue, 2012-05-22 14:55 | login or register to post comments

covalent bond

I believe it's a true covalent bond. Instead of an -OH group on the cellulose, the dye reacts with either an amine group (-NH2) or with an -OH group in an amino acid side chain, in very much the same way. The reaction occurs via nucleophilic substitution.

-Paula

By pburch at Tue, 2012-05-22 16:10 | login or register to post comments

And it's the same bond with either

And it's the same bond with either acid or alkali? If so, that would be very interesting to me...and makes me wonder why acid dyes are recommended for protein fibers, rather than Pro MX (or Cibacron F) with acid + heat? (Since the non-Lanaset acid dyes don't bond as strongly, it would seem that fiber-reactive dyes would be superior.)

Website: http://www.tienchiu.com
Blog: http://www.tienchiu.com/category/blog-posts

By tienchiu at Tue, 2012-05-22 21:24 | login or register to post comments

different bond!

No, it's absolutely not the same bond, when you're dyeing wool, with acid versus alkali. With an acid, when you're dyeing wool or another protein fiber, you're going to be getting primarily the type of bonding seen with acid dyes. Though a tiny number of reactive-type reactions might creep in there, there will be very few at neutral pH, and less still at lower pH, so essentially you're not going to see it. The low pH prevents the formation of an anion from the fiber; without the fiber-anion, there's nothing that's going to attack the carbon that has a chlorine atom on it. (At a high pH the excess hydroxide anions present 'steal' an H off of the cellulose or protein molecule, which activates it for the dye reaction.)

For comparison, since cellulose won't "do" acid-type bonding, you won't see much dye bonding of it occur at or below a neutral pH. I think this also gives you an idea of how much covalent-type bonding you could see when dyeing wool at a neutral or low pH. Quoting from elsewhere, my son (in a different year's science fair experiment than I quoted before) found that "His three swatches dyed at pHs of 2.5, 4, and 7 were all alike, a pale pink, as expected, but the one at a pH of 8 was only a little less bright than the best one. His pH 9 was almost identical to pH 10, which was the best pH he tried. The one with a pH of 12 was pretty intense, but a little spotty, and the one with a pH of 13 was of a medium intensity." I think the pale pink at the lower pHs was due to staining due to the substantivity of the dye (i.e. vague tendency to associate with the fiber, probably via Van Der Waals forces), not to some ability of the cellulose to form acid-dye-type-bonds. [My son had difficulties with choosing a science fair project in time and asked for help both years in deciding on one. Having all my books and chemicals and labware around made the whole thing much easier.]

At neutral pH, I think you're going to mostly get acid-dye type reactions; at a pH below 7, you will get just the acid type bonding.

When you dye wool with Procion MX and similar dyes at an acid pH, the resulting bonds will not be covalent, but instead will be hydrogen bonding and salt linkages. (See What kinds of chemical bonds attach dyes to fibers?.) You should see, after all excess dye has been washed out, that the dye in the resulting dyed wool is much less resistant to boiling than wool that was been dyed at a pH above 7. You might do a test of this at a compromise pH around 8, which is high enough to get the covalent-bond-producing reaction, but low enough to not damage the wool too much.

Other types of acid dyes are more permanent than Procion MX-dyes-used-as-acid-dyes. Procion MX and Cibacron F dyes, when used as acid dyes, an an acid pH, perform most like acid leveling dyes. Acid leveling dyes are the least washfast of the generally used acid dyes, and Procion MX dye is similar when applied at an acid pH. Acid leveling dyes are great for leveling, as their name implies, but not generally nearly as washfast as acid milling dyes or Lanaset or Lanasol dyes. Notice that washfastness tests for wool dyed with Lanaset dyes and Lanasol dyes and (I think maybe) premetallized dyes all call for wash water at a temperature of 140°F. Try that on acid leveling dyes, such as the dye in Rit dye, and you're going to see a huge amount of washout and bleeding in the laundry. Most acid dyes are subjected to test-washing at temperatures not to exceed 104°F (40°C), because their bonding is simply not as permanent. (See the washfastness tests in the charts on my lightfastness page.)

The covalent bonding of Procion type dyes is produced by a reaction with a chlorine-bearing carbon on the reactive ring. The acid dye bonding of Procion Dyes is produced by interaction with the sulfonate groups that are present at various places on the chromophore in order to make the dye soluble in water. The two different types of bonding, the acid dye bonding and the high-pH reactive dye bonding, occur at different sites on the dye molecule.

None of this is true for the vinyl sulfones, by the way, also known as the Remazol dyes, which can form a true covalent bond with wool when boiled for an hour at moderately low pH, even though they also form a covalent bond with cotton at high pH. That class of reactive dyes has to be considered separately.

-Paula

By pburch at Wed, 2012-05-23 06:12 | login or register to post comments

Thanks so much for the clear

Thanks so much for the clear information. I've been dying to know how the chemical reactions work for some time.

Thanks!

Tien

Website: http://www.tienchiu.com
Blog: http://www.tienchiu.com/category/blog-posts

By tienchiu at Wed, 2012-05-23 14:06 | login or register to post comments

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