Iron sulphate to colour leather black

[TomE]

The "copperas" in the Hasluck recipe above is iron sulfate crystals.  He adds "log chips" and "gall nuts" that I guess are for tannins.  The "gum arabic" is polysaccharide and probably helps with slicking the edge.  Old school recipe. 

@Dwight of course you can buy Fiebing's pro black dye from their online store or from Springfield Leather, etc.  There is something different about black pro dye compared with the browns I use more often.  The black tends to dry out the leather more (oiling fixes it), and I notice an oily residue (not seen with the browns) when I rinse the dauber with water. 

[ScottEnglish]

Thanks for telling me what copperas are TomE. Now I realize why you included Hasluck's recipe in your post.

[Dwight]

4 hours ago, TomE said:

 

@Dwight of course you can buy Fiebing's pro black dye from their online store or from Springfield Leather, etc.  There is something different about black pro dye compared with the browns I use more often.  The black tends to dry out the leather more (oiling fixes it), and I notice an oily residue (not seen with the browns) when I rinse the dauber with water. 

I got the impression they were not making it any more . . . I used it for the last 15 or more years . . . had a black project last month . . . USMC was all they had.

I'd probably give it to someone who drove over to pick it up.

For now . . . I just might jump on the vinegaroon band wagon . . . still "contemplating" . . . but thanks . . . I'll check into Springfield Leather as well.

May God bless,

Dwight

[TomE]

3 hours ago, Dwight said:

I got the impression they were not making it any more . . . I used it for the last 15 or more years . . . had a black project last month . . . USMC was all they had.

I'd probably give it to someone who drove over to pick it up.

For now . . . I just might jump on the vinegaroon band wagon . . . still "contemplating" . . . but thanks . . . I'll check into Springfield Leather as well.

May God bless,

Dwight

Fiebing's online shop lists  black Pro Dye in 4oz, quarts, and gallons.   I found this old harness maker's manual with recipes for many different "blacking" dyes (Chapter XXV). https://upload.wikimedia.org/wikipedia/commons/8/80/The_harness_makers'_illustrated_manual._A_practical_guide_book_for_manufacturers_and_makers_of_harness%2C_pads%2C_gig_saddles%2C_etc._.._(IA_cu31924000022636).pdf  It's a fun read if you're easily entertained like me.

[Dwight]

2 hours ago, TomE said:

Fiebing's online shop lists  black Pro Dye in 4oz, quarts, and gallons.   I found this old harness maker's manual with recipes for many different "blacking" dyes (Chapter XXV). https://upload.wikimedia.org/wikipedia/commons/8/80/The_harness_makers'_illustrated_manual._A_practical_guide_book_for_manufacturers_and_makers_of_harness%2C_pads%2C_gig_saddles%2C_etc._.._(IA_cu31924000022636).pdf  It's a fun read if you're easily entertained like me.

Thanks TomE

May God bless,

Dwight

[ScottEnglish]

I've used a solution of water and iron sulphate to successfully colour natural veg tan leather. It does work. I presumed it did as a member of these forums said they use it instead of vinegaroon. The final colour is black with a hint of grey. If leather is immersed in a weaker solution or for a shorter duration the colour is grey with a hint of blue. I understand from the aforementioned forum member that unlike vinegaroon it's necessary after colouring leather in this way to wash it in water to remove weak sulphuric acid.

 

[Matt S]

22 hours ago, ScottEnglish said:

I've used a solution of water and iron sulphate to successfully colour natural veg tan leather. It does work. I presumed it did as a member of these forums said they use it instead of vinegaroon. The final colour is black with a hint of grey. If leather is immersed in a weaker solution or for a shorter duration the colour is grey with a hint of blue. I understand from the aforementioned forum member that unlike vinegaroon it's necessary after colouring leather in this way to wash it in water to remove weak sulphuric acid.

 

Black strikers like iron sulphate and vinegaroon give a darker or lighter effect based on the amount of tannin left in the leather. There's a chemical reaction which occurs within the leather where tannic acid oxidises the iron in the iron-containing solution into black iron tannate. The less tannic acid left in the leather after tanning the less pronounced the effect. Tannins (and so the blacking effect) can be increased, usually with a solution of black tea. In South America they strike rawhide black using this method (rawhide, being untanned, has no tannins). Solution strength and contact time also affect how deep a shade is produced.

It's not unusual for black-struck leathers to look blue-grey until some grease or oil is added.

I think that there may also be some variation based on how much grease/oil is in the leather, as that would reduce the ability of a water-based solution to contact the leather fibres. Even natural/russet/tooling leather often has a small amount of oil or grease added during production.

[ScottEnglish]

Thanks for your post Matt S. I'm not the sharpest knife in the drawer and struggled at school. But your above explanation of the science is straightforward. Thanks for taking the time to enlighten me. And I trust others also.

Scott

[Doc Reaper]

On 2/15/2023 at 5:38 AM, ScottEnglish said:

Thanks for your post Matt S. I'm not the sharpest knife in the drawer and struggled at school. But your above explanation of the science is straightforward. Thanks for taking the time to enlighten me. And I trust others also.

Scott

Then I need someone to look at this and help me understand what happened. I purchased the   $10 bag of iron sulfate, added it to a 3/4 full jar (Libby’s chicken gravy jar) of water, I used 2 jar lids full of the iron sulfate. All I got was a light gray in return, it turns medium dark gray with neatsfoot oil. I’m experimenting with the iron sulfate (30%) while I was also checking out my one week old vinegaroon and just one drop of the roon dropped onto the iron sulfate test strip, it turned it dark blue in the blink of an eye. While both mixtures took a bit of time to color the leather the two coming together was like wow fast! The picture shows 2 strips - both test strips are test for the iron sulfide. The round mark is where the drop of groon landed by chance

Edited February 21, 2023 by Doc Reaper
Grammer

[ScottEnglish]

Hi Doc Reaper. Matt S is the fellow you need a post from.

My initial experience of a solution of iron sulphate and water was disappointing until I increased the amount of iron sulphate in the solution. I left the scraps of leather soaking in the solution for several hours.

Matt S said something about black tea in combination with the iron sulphate solution making it more effective. Hopefully, he will help us out.