Question About Vinegroon..

[Kelvandor]

After reading a couple of the post here on the Vinegroon process it struck me that I know this....or at least, I know a slightly different form of this:

The process sounds almost exactly like the Iron-Gaul ink formulas and processes. Maybe someone here with a better understanding of the details can point out the differences?

If they are virtually the same process, I would tend to get a bit worried about using Vinegroon. There is a lot of information published about the deteriorating effects of Iron-Gaul ink and the problems archivists are having in preserving older documents because of it.

Has anyone noticed these effects on older vinegroon'ed leather? Or is the process different enough that it's not a worry?

-Kel

[amuckart]

Nice to see someone else having this thought.

I've used this stuff quite a lot making historical goods, but I've given up on it for now until I can find a decent source of strong tannins. I'm thinking logwood or oak galls here, tea doesn't cut it. NZ doesn't have gall wasps so we don't get oak galls. I could import logwood but it's hell expensive to get over here.

The acid is the problem in oak gall ink. It's less of an issue here provided you neutralise the acid afterwards with a baking soda rinse but the big problem I've had is the dye destroying the grain surface of the leather because the iron / tannin reaction is stripping tannins out of the leather and leaving it brittle. It doesn't matter how well you oil or condition it afterwards, you've still bound up a bunch of the tannins in the leather and that's going to have an effect down the track. I've got a medieval belt I dyed with this and the grain is just peeling off the leather.

I've got a copy of M. C. Lamb's early 20th century book Leather Finishing: Including Dyeing, Staining and Finishing which documents recipes for iron black and talks about the necessity for adding logwood extract to prevent the dye destroying the grain surface of the leather. I need to dig it out anyway to respond to a PM question about it so I'll drop the info on here too.

[amuckart]

Lamb says this:

Regarding Logwood:

"The most important use in connection with leather to which logwood is put is in the dyeing of blacks in conjunction with an iron mordant. For brush dyeing or staining, a strong infusion of the logwood or logwood extract is employed, previously made slightly alkaline with ammonia or sodium carbonate, in order to increase the dyeing power and to assist in "cutting" the grease in the case of greasy leather. Another function of the alkali is to prevent the logwood infusion from striking through, that is from penetrating the leather. The alkali is not so important when the logwood is used for dyeing blacks in the bath."

A few paragraphs further on:

In staining blacks it is very necessary that plenty of the logwood infusion should be applied to the leather, especially if this is at all lightly tanned. Unless there is plenty of tannin and colouring matter to unite with the iron, the iron will combine with what there is of tannin matter in the leather, and render it brittle and liable to crack. If too much iron is used, the leather may be completely ruined. The writer has seen many cases where leather has been rendered brittle by too little logwood and too much iron."

Any errors in there are mine, I transcribed those paragraphs by hand.

At some point I will photograph and OCR the section on logwood and iron black.

[ChuckBurrows]

There is a lot of information published about the deteriorating effects of Iron-Gaul ink and the problems archivists are having in preserving older documents because of it.

Has anyone noticed these effects on older vinegroon'ed leather? Or is the process different enough that it's not a worry?

1) Old documents were done on some form of parchment, a type of rawhide i.e. untanned leather that has been lime. Vinegar black on the other hand is used on leather, a tanned product, two quite different materials thus they cannot be directly compared. Much of the deterioration in old documents and leather is in fact due to the high sulphur content in smog in is a major culprit especially with iron/gall ink that uses iron sulphate as the source of iron - the sulphur mix/content turns to sulphuric acid and causes the problems. Vinegar black is ferric acetate a different source for the chemical reaction with the tannins in the leather.

2) I have been using vinegar black - - for over 40 years and on my own gear I have seen no deterioration when done as I have noted elsewhere. I have also examined and repaired old leather from as early as the 1820's that was "dyed" with vinegar black and the stuff that was properly taken care of over it's life has shown no more deterioration than is normal for old leather.

3) The quote shown is about using iron as a mordant with logwood - a process that is not the same as using straight vinegar black, which is nothing more than a small amount of iron dissolved in vinegar - there is not need to infuse a large amount of iron to get a good vinegar black. Another thing that can cause brittleness is the over use of an alkali - IMO ammonia or sodium carbonate are much too alkaline and will cause draying/cracking otherwise known as alkali burn. Sodium bicarbonate aka baking soda which I recommend is milder and when used sparingly has never caused a problem but does help set the black.

Vinegar black (aka ferric acetate) when done right is not the same as using iron as a mordant with logwood - I have used both and prefer the simplicity of the vinegar black. As I have noted before, for the deepest black apply a good coat of STRONG black tea (brew it one to one water tea, and steep for at least 15 minutes sealed well) to increase the tannins. This should also obviate any of the problems noted in your quote. Other sources of tannins are most tree barks, leaves, nuts, seeds, etc. see this link - http://www.braintan.com/barktan/2tannins.htm - Most any bark sold as garden mulch is excellent for bark tanning (assuming it hasn't been left out in the rain a bunch).

The acid is the problem in oak gall ink. It's less of an issue here provided you neutralize the acid afterwards with a baking soda rinse but the big problem I've had is the dye destroying the grain surface of the leather because the iron / tannin reaction is stripping tannins out of the leather and leaving it brittle. It doesn't matter how well you oil or condition it afterwards, you've still bound up a bunch of the tannins in the leather and that's going to have an effect down the track. I've got a medieval belt I dyed with this and the grain is just peeling off the leather.

FWIW - tannins are a source for tannic acid ......so I'm not sure how then the acid in oak gall is the problem since adding tannins also increases the acid level. Veg tanned leather itself should be somewhat acidic - about 4.5 on the PH scale is about right. Neither do tannins make the leather soft - leather straight out of the vats and dried is hard and can be brittle - it is the currying i.e. re-application of fats and oil that gives leather it's "soft" and or other malleable qualities. See the above link for sources of tannins.

Try oiling immediately after "dying" Do not let dry first........

I've never had the grain layer peel off or crack (except when using too strong of a neutralizing alkali wash which caused the surface to "burn") so I can't offer any other advice than: use as weak a ferric acetate mix as possible, "neutralize" with a mild baking soda and water mix (distilled water IMO is best), rinse well with water, and apply your choice of oil on both sides while wet.

Hope this helps...........

Here's a good article on ink corrosion on both paper and parchment -

he could clearly prove a correlation between excess iron(II) sulphate in the inks and the occurrence of ink decay on paper documents

Edited March 13, 2010 by ChuckBurrows

[amuckart]

Hi Chuck,

3) The quote shown is about using iron as a mordant with logwood - a process that is not the same as using straight vinegar black, which is nothing more than a small amount of iron dissolved in vinegar - there is not need to infuse a large amount of iron to get a good vinegar black. Another thing that can cause brittleness is the over use of an alkali - IMO ammonia or sodium carbonate are much too alkaline and will cause draying/cracking otherwise known as alkali burn. Sodium bicarbonate aka baking soda which I recommend is milder and when used sparingly has never caused a problem but does help set the black.

Thanks for that. When you say "small amount" do you have a ratio you stick to, or do you just eyeball it?

Cheers.

[ChuckBurrows]

Hi Chuck,

Thanks for that. When you say "small amount" do you have a ratio you stick to, or do you just eyeball it?

Cheers.

You're welcome - I'm an eyeballer, but it's about one degreased hunk of 4/0 steel wool (or equivalent iron scrap) to about a quart of vinegar. I prefer cider vinegar myself, but any will do. Also heating it will speed the process. Once it's completely dissolved I let air for a couple days to help release any residual gases. Test the mix and if it "needs" to be stronger add a bit more steel wool at a time until it quits dissolving it. When it quits dissolving the iron strain off the clear liquid and save the leftovers for the next batch.

[MADMAX22]

Chuck's instructions have worked for me for the past couple of years. Ive scene several of my projects that being only a couple of years are still in excellent shape.

One thing to note is that different hides will react differently in all areas. Ive had some get a little tougher and need alot more oil while others had allmost the same temper as before I blacked them and they only needed one normal coat of oil before the finishing process.