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aneel.tariq
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| Posted: 14 January 2010 at 4:51am | IP Logged
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Dear forum members,
In dyeing process,which kind of parameters should we adopt to get bright colours especially with dull dyes.
1: Dyes mixing
2: Retanning
3: Rechroming
4: Fatliqouring etc.
Regards
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Aneel
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zercas
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| Posted: 14 January 2010 at 8:29am | IP Logged
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Wait for David he is the one that tackles those open en questions 
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Zercas
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DavidR
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Sometimes rechroming in the presence of aluminum will help later fix more anionic dyestuff per fiber surface unit of leather/collagen, as more charged aminos will be present, making the color deeper. But if the dye itself has inherent color problems arising from its synthesis, then it will not help. Metalizing of certain dyes by the presence of cationic metallic agents will sometimes increase intensity of color of the dyestuff complexed with the metal, but often changes the hue so chemical houses do not recommend it as a procedure, for it ruins their color prediction schemes. On the other hand, anionic retannage and fatliquoring will always weaken the dyestuff effect and dulls the color.
Edited by DavidR on 14 January 2010 at 10:55am
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DavidR
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| Posted: 20 January 2010 at 10:41pm | IP Logged
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Dear Tariq: Please give me an idea of the tannage involved in the baby (Calf) Buffaloes you are trying to dye. OK?
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aneel.tariq
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| Posted: 21 January 2010 at 1:57am | IP Logged
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This is normal mimosa veg tannage .Dyeing step should be after retanning and fatliqouring.
We start our retanning with oxalic acid wash.
slight chroming than retanning fatliqouring and opn final dyeing.
I think it will help you .
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Aneel
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DavidR
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Vegetable main character does not give bright colors with anionic dyes! Please try a little (~0.3%) aluminum sulfate with the formic acid wash before rechroming and see the effect on the dyeing intensity, before trying a cationic dyeing auxiliary such as a quaternary amonium containing resin.
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kallenwe
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| Posted: 21 January 2010 at 9:40am | IP Logged
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Putting metals (Al or Cr) on top of that veg. is going to give a much darker color.
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DavidR
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Chrome is already being offered! The aluminum will make the leather much more reactive to dyestuffs and at least would facilitate dark, but intense colors! If vegetable character feel is so desirable in this leather, the darkness is a consequence of this. To make a leather with similar feel but being able to dye in bright and pastel shades, you must go to Zirconium tannages. If I understand correctly, this buffalo calf is still tanned in pits, making it impossible for Zirconium tannage because of cost reasons.
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mexgerber
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You can try a sandwich dyeing: dye first with a 60% of your total dye offer before fatliquoring, run for 20-60 minutes; fatliquor, run for 60 minutes; add formic acid run 10+30' and drain bath. In a new bath offer: 1% Amollan R (or similar products based on lightly cationic amine derivatives ethoxylized, that in this case will work as a mild charge changer), run 40 minutes; drain bath; top dye in a new bath with the 40% of your total dye offer, disolved,run 10'+20'; add formic acid, run; drain bath; wash with 400% float for 10 minutes; drain; 200% water at 30ºC + 0.5 Bastamol DR run 30', take out load. It should give you brighter shades.
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zaghlolman
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dear mexgerber,
You are ready to offer a way to implement
but I think aneel, need more than these
We talked earlier about the topdye
and how can get bright colours
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Leather Chemists : Leather Discussion
Topic: Dyeing mixture for bright dyes
