Dyed leather is returning to original color??!!

[AmericanSon]

So, I bought some hides and dyed them dark brown and light brown using mainly Angelus pro dyes.  Some pieces were dyed with full 100% dye, some were cut with a reducer.  All are fading back to original color of tanned hide.

This is a brand new phenomenon for me.  I am certain it is the hide.  Just not sure how to remedy.  Thank you in advance for any experience.

Hides.  Chrome Tanned cowhide.  Purchased from a leather lace tannery that closed its doors and moved operations to China.  This was a bulk purchase with about 4,000 lbs. left of full hides and half hides.

Thanks again for any help.

[Mablung]

How did you dye the hides? Airbrush, daubers, etc.? Were the hides sealed before you dyed them? Few more specifics on the hides’ pre-dye condition and your methods would be helpful. 

[AmericanSon]

Thank you.  Dipped dyed the pieces.  Plenty of coverage.  No seal on hides; we soaked them for hours before dye bath.  Can think of anything else but I'm gonna be excited if someone can figure it out.

[Mablung]

Huh. That’s an interesting conundrum. Which is to say, I don’t know what the answer is, although that may simply be because I haven’t tried to dye chrome tan leather; all the chrome tan I’ve dealt with is already colored the color I wanted. Could it be that the chemistry of chrome tanning prevents the hide from holding dyes? I don’t know the chemical makeup of the Angelus pro dyes, but I know the Fiebing’s pro dyes are spirit-based, allowing them to penetrate veg tan more effectively. That tells me there’s some manner of chemical reaction going on there, which may not play well with chrome tannage. 
 

I’m just spitballing/thinking out loud, in case one thought or another turns out to be helpful. 

[AmericanSon]

1 minute ago, Mablung said:

I’m just spitballing/thinking out loud, in case one thought or another turns out to be helpful. 

Thank you.  I'm hoping that enough spitballers will help me get it figured out.

I believe these hides were from Auburn Tanning before they sold out to China for their lace (not sure what all they are doing now in house)  regardless, they had an entire separate facility that would color the hides.  So, these we not colored in the tanning process.  Anyway, perhaps the clue lies in their process.  I still have a great opportunity with 4000 lbs of cowhide to purchase and I can not seem to get it figured.  

Thanks again for your response.

[fredk]

1 hour ago, AmericanSon said:

Hides.  Chrome Tanned cowhide.  Purchased from a leather lace tannery . . .

That thar is a clooo.

Chrome tanned, in my experience wont take a dye and keep it unless it has been treated beforehand. I use cellulose thinners to prepare chrome tan. Also you are using a water-based dye. I use an oil -based dye on chrome tan

[AmericanSon]

Thank you Fred.  I think both the pro from Angelus and the feibings are both alcohol based dyes.  But I am interested in the cellulose thinners you use to prepare the leather.  Can you tell me more?  Thank you.

[AmericanSon]

Here's the feibings I used and the pro is the same if I'm not mistaken.

[fredk]

Alcohol based can still be thinned and washed out with water

I simply give the chrome tan a good wetting and washing with the cellulose thinners and whilst its still damp I dye it

[Wepster]

https://en.wikipedia.org/wiki/Lacquer_thinner

AKA cellulose thinner

[AmericanSon]

Is this the same thing?  Thank you.

[TomE]

Have you tried dip dyeing a piece that is dry?  You mentioned soaking the hides (in water?) before dyeing.  That might require longer for the water be displaced by the dye solution.  I certainly see that wet edges take up less Pro Dye than dry edges.  Does the lighter color develop after the leather is fully dry or while it is drying?  It sounds like you're in touch with the tannery so I would ask them for dyeing tips. 

I am not familiar with Angelus deglazer but the Fiebings deglazer is a mixture of organic solvents (MSDS mentions ethyl acetate and ethanol) and I think it's designed to minimize removal of existing dye from the leather.  Folks use acetone and lacquer thinner for thinning Fiebings leather dye and pro dye, instead of Fiebings dye reducer, which might be an milder alternative for pretreating the leather before dyeing.

[AmericanSon]

Thank you Tom for your comments.  Yes, I have tried "dry" dying, wet dying and it all does the same.  There is not a variation from edges to middle.

These hides are a dry wet/blue if you know what I mean.  A handful of hides were green and they accepted the dye the best but are now fasing back to green.

Weird for me but someone is going to know what is happening.

[tsunkasapa]

17 hours ago, Mablung said:

Could it be that the chemistry of chrome tanning prevents the hide from holding dyes?

There is the issue. Chrome does not take dye like veg tan. At one time there was a line of dyes for chrome. Feibing's I believe.

[AmericanSon]

Excellent idea.  Let me try and track that down.  Thank you.

[TomE]

The book "Tanning Chemistry The Science of Leather" by Covington and Wise has a chapter on dyes.  They mention that too much surface reaction during tanning with chromium salts can cause splotchy coloring with dyes or act as a complete resist to dyes.  From what I could gather in a quick read the amount of surface reaction with chromium is determined by the tanning conditions (pH, chromium concentration, etc) so dye uptake is a problem with some, but not all chrome tanned leathers.  The authors say chrome tanned leathers are cationic (positively-charged) and therefore generally react well with acid dyes.

 

This thread has some information on dyeing chrome tanned leather.  

 

A comment by veedub3 in this thread mentions Dharma acid dyes for leather and provides a link.  Perhaps they can help.

 

[AmericanSon]

1 hour ago, TomE said:

The book "Tanning Chemistry The Science of Leather" by Covington and Wise has a chapter on dyes.  They mention that too much surface reaction during tanning with chromium salts can cause splotchy coloring with dyes or act as a complete resist to dyes.  From what I could gather in a quick read the amount of surface reaction with chromium is determined by the tanning conditions (pH, chromium concentration, etc) so dye uptake is a problem with some, but not all chrome tanned leathers.  The authors say chrome tanned leathers are cationic (positively-charged) and therefore generally react well with acid dyes.

 

 

Really good info here.  Thank you.  I am sure it is the salts but I just can't figure our why.  The dye job looks so great for about a week but once it hits the sun forgetaboutit.

 

[Dwight]

1 hour ago, AmericanSon said:

Really good info here.  Thank you.  I am sure it is the salts but I just can't figure our why.  The dye job looks so great for about a week but once it hits the sun forgetaboutit.

 

In 20+ years . . . I have had one similar problem.

I could not find the exact shade of grey I wanted for "MY" holster . . . so I invented it.  I kept playing with black, saddle tan, and british tan until it did what I wanted . . . and I was some kind of seriously glad.  I wanted almost a battleship grey for it . . . 

Dyed the holster and belt . . . all was good . . . about a year later I noticed the black seemed to be leaving . . . giving me a brownish red holster . . . with a mostly grey belt.

Holster keeps losing the black . . . belt I think has stabilized  . . . 

Not big deal . . . i'ts my personal holster . . . and  I can live with it.  Just glad it was not a customer . . . 

May God bless,

Dwight

[alexcobe]

10 hours ago, AmericanSon said:

The book "Tanning Chemistry The Science of Leather" by Covington and Wise has a chapter on dyes.  They mention that too much surface reaction during tanning with chromium salts can cause splotchy coloring with dyes or act as a complete resist to dyes.  From what I could gather in a quick read the amount of surface reaction with chromium is determined by the tanning conditions (pH, chromium concentration, etc) so dye uptake is a problem with some, but not all chrome tanned leathers.  The authors say chrome tanned leathers are cationic (positively-charged) and therefore generally react well with acid dyes. Really good info here.  Thank you.  I am sure it is the salts but I just can't figure our why.  The dye job looks so great for about a week but once it hits the sun forgetaboutit.

 

Maybe you should change your finishing methods to help improve skin stability. That's an option)

[blue duck]

So far from an expert, but I wonder if your answer is in where you got it from. You said it was a lace maker. I have no idea the difference in the 'recipe' for making a lace hide vs a bag hide or whatever, but there is one. I have done crusts and they need a finish after dying. I didn't see that you had done that yet. That might help? As far as I have found, the finish I get isn't  the same as a commercial one. It may also be that its not crust meant to be dyed, but

rather a 'finished' hide.