AmericanLongRifles Forums
General discussion => Contemporary Accoutrements => Topic started by: BrownBear on May 04, 2010, 08:27:25 PM
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I finally got around to making and trying the vinegaroon dye (rusty iron + vinegar) described in TC Albert's book "Recreating the 18th Century Hunting Pouch." Excellent!
It's a clear dye, but turns the leather progressively gray, then blue/black, then blue/gray as it dries. It's "blue suede shoes" blue until you top it with brown paste shoe wax as TC recommends, but the end results are just outstanding. It really brings out the texture in leather and looks about 200 years old right off the bat. I'll post pics when I get a chance.
My question is, are there other folk or traditional or natural leather dyes a guy might use. I'm REAL interested in results and formulas, but want something with a little more "emphatic" results than what you get with strong coffee or tea to shade the leather.
Thanks for any replies, and especially links to sources. I tried googling, and as always these days, mostly got companies trying to sell me something or lure me into using their own search engines.
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Brown Bear,
REALLY enjoyed your description of the colors turning blue.
Back in the early 1970's, the owner of the Tandy leather store in Fredericksburg, VA taught me about using Navy Blue or Dark Brown dye first and then black on top to get a deeper/richer black final color that showed up better as "black" in direct/strong sunlight. From your description, I now can see how the vinegaroon dye did the same thing.
Gus
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Hmmmmm. I've been buying all my black leather due to unhappiness with my own dying. Now you've given me a couple of alternatives to try. Thanks!
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The final black color that you get when you use Royal Blue dye first, is the richest black color. When you hold it to the bright sunlight just right, you wll see some of the blue in the color.
Using a dark brown leather dye first actually looks more authentic to 18th and early 19th century leather color.
When you compare the final color using either of these methods vs only using black dye, you should see a surprising difference out in the bright sunlight.
Glad to be of help.
Gus
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I'd love to learn more about this too being a newbie.
I've looked at just about every picture posted here and would love to know how you guys do it.
I tried walnut dye but the results were less that satisfactory. Perhaps my dye is too weak but it barely stained the lining let alone the leather.
Rich Baker
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I'm hearing stories that the vinegaroon should be used only on true oak-tanned leather, and that it's real hard on cheap "veg tanned" leather, Rich. Supposedly it really weakens the leather after a couple of weeks. Stay tuned, because in fact I used Tandy's cheaper veg tanned, and 2.5-3 oz to boot. Sounds like I'm a prime candidate for leather failure. Time will tell (literally!).
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BrownBear,
The vinegar and iron does dry out the leather. I did have trouble with some cheap Tandy leather that just wasn't tanned well to begin with. It was stiff to start and the vinegar turned it into cardboard. I have used other cheap leather from Tandy that was very supple to start and I couldn't change that no matter what I did to it. Now, I select my leather carefully from the side. The quality can vary from one part of the side to another. I have even had the front and back of a once piece bag finish up differently. I think the main difference between a cheap side of leather and an expensive side of leather is the amount of usable leather in each. I guess that I have learned that it is better to by the expensive leather.
In any case, I do liberally apply mink oil to all my leather when I am finished with it to add back the oil I took out with all my washing, tooling, dying and rinsing.
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Thanks Mark. Mine never did get stiff, whether due to the lighter weight or that particular tanning vat.
I checked it, and yeah, I'm getting some cracking. I gave it a good dosing with mink oil, and will do so again tonight. It sure soaked it up! Hopefully that will help "arrest" the process.
Actually the surface cracking is just right for antiquing, as I've seen done with Easy Off. It adds to the appearance rather than detracts. If I can stop it where it is, I'm in tall clover. If it keeps on cracking, I've got a wall hanger on my hands, but it's a good looking one! ;D
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After a couple of coats of mink oil (actually mink oil patch lube from TOW) and a couple of days to soak it in, I have to say I like the results even better than before. It stopped the cracking and darkened the leather very slightly.
I'll be keeping my eye on it, but for the time being the leather is very supple while looking quite aged due cracking and wrinkles in the right places. I think oiling the leather thoroughly after dying is a "missing step" in my original conception of what was needed. A year from now I may feel differently, but I think with the help of contributors to this thread, I've found the combo that's right for me. Cheap, thin veg tan leather, vinegaroon, paste shoe polish, and mink oil.
This is a very light bag, and with a lightweight horn, I doubt I'll even notice I'm wearing it on long hunts. Can't beat that if it looks good and wears well. Got the "look good" part to my tastes, but time and rough treatment will have to be applied to measure the "wears well" part.
Pictures to come when I get around to it in the next day or so.
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Cheap, thin veg tan leather, vinegaroon, paste shoe polish, and mink oil.
That pretty succinctly describes my process. ;D
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I finally got around to making and trying the vinegaroon dye (rusty iron + vinegar) described in TC Albert's book "Recreating the 18th Century Hunting Pouch." Excellent!
It's a clear dye, but turns the leather progressively gray, then blue/black, then blue/gray as it dries. It's "blue suede shoes" blue until you top it with brown paste shoe wax as TC recommends, but the end results are just outstanding. It really brings out the texture in leather and looks about 200 years old right off the bat. I'll post pics when I get a chance.
My question is, are there other folk or traditional or natural leather dyes a guy might use. I'm REAL interested in results and formulas, but want something with a little more "emphatic" results than what you get with strong coffee or tea to shade the leather.
Thanks for any replies, and especially links to sources. I tried googling, and as always these days, mostly got companies trying to sell me something or lure me into using their own search engines.
In terms of historical coloring of leather.
With bark tanning.
There was a point in the hide tanning process known as the "dunging" step. The type of dung used would influence the final color of the leather.
The type of bark used as the tannic acid source would also influence the final color of the leather. Some of this depended on where the tannery was located and what sort of "tannbark" trees were to be found in that particular area.
Iron dye and leather.
The "standard" in Eastern tanneries was nitrate of iron as the leather dye. Quicker to make that messing around with digesting iron in vinegar to get a ferric acetate solution.
With bark tanned leather there will be a reaction between the tannic acid in the leather and the iron dye being applied. You get a black color. Same as staining a curly maple stock and having the curl turn black due to the reaction betwenn tannins in the wood and an iron stain on/in the wood.
Some years back some museum tried to claim that the mineral pigment dyes made with any sort of acid would cause a more rapid aging/deterioration of the leather. Causing it to become brittle and crack. That was laid to rest a few years later. The aging problem with the leather was more an issue of the air around the leather during storage and use. Sulfur fumes in the air would get into the leather. It was the sulfur bearing gases forming an acid in the leather with moisture in the air. A real problem when coal replaced wood in heating stoves in homes. If you ever tended a coal furnace that burnt Pennsylvania Anthracite coal you get a good idea of just how much sulfur was kicked into the air with a coal stove or heating furnace.
Bill k.
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That's superb background and really helpful, Bill. Thanks!
I'm in conversations with local archeologists and curators to learn more about "leather" tanning and coloring up here. Of course, it was 99% marine mammals, but I'm interested to glean any local materials that have promise.
And you raise an excellent point about the influence of things added in the tanning process versus used afterward for coloring. I suspect there's a world of differences, and they can occur at every step along the way.
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Late to the game.........
Vinegar black aka vinegaroon
My original recipe came from a mid 1800's harness manual, but it dates back at least to the Romans:
VINEGAR BLACK
For giving color to the grain of leather there is no blacking that will at all compare with the well known vinegar black. This may be made in various ways. The simplest, and, without doubt, the best, is to procure shavings from an iron turner (note: some folks get the turnings from brake drums) and cover them with pure cider vinegar; heat up and set aside for a week or two, then heat again and set in a cool place for two weeks; pour off the vinegar, allow it to stand for a few days, and draw off and cork up in bottles. This will keep for a long time, and, while producing a deep black on leather, will not stain the hands.
FWIW - I've been using this blacking formula for 40+ years and here's how I do it most times:
I use de-oiled 4/0 steel wool: dip in acetone, squeeze out the extra and hang to dry - then tear or cut into small pieces. Add one pads worth of the de-oiled steel wool to one quart of white or cider vinegar (I prefer the latter) I use those plastic coffee "cans" and punch a single small hole in the lid to let of any gas buildup. If you let it set in the hot sun it will speed the reaction. I let it "cook" for about two weeks until there is only a light vinegar odor left and/or the bulk of the steel wool has been dissolved. I also keep a new batch "cooking" all the time so I have a constant supply.
If need be for a deeper black, apply a bath of strong black tea first (this increases the tannins whihc react with the iron) and let it soak in good, then apply a generous amount of the vinegar black. Let set for about a half hour and then rinse with a mix of baking soda and warm water, about a 1/8 cup soda to a half gallon of water, apply let set for a few minutes, and then rinse off. While still damp apply a light coat or two of your favorite saddle oil on both sides if possible. Once dry, top coat as normal
Experiment - I test a piece of each new hide without oiling to see how well it takes the blacking, if need be I'll do a second black tea mix to darken, then apply the oil which also helps darken.
Instead of steel wool you can use chopped up bailing or fence wire - the smaller the better since it will dissolve in the vinegar bath faster.
re: the smell -
1) Keep adding iron/steel wool until it quits dissolving it, this will use up all of the acid. Also stir the mix while it's brewing in order to aid in the off gasing and to introduce as much oxygen as possible. Strain/filter the mix to remove any left over iron - use it for your next batch.
2) Once done and dry hang in front of a fan - the air movement will help eliminate any residual odor - mine seldom smells for more than a day at most.
3) Be careful with the baking soda rinse, too strong, too long can cause the leather to "burn" - not a good thing. Just a quick dip or wipe down with the NS mix is enough and be sure to after rinse well with clear, clean water - if your tap water is high in iron use bottled water.
I have also used ferric nitrate (what we also call Aqua Fortis), but find it works no better and can tend to burn the leather more than than the ferric acetate ......
Other period dyes:
Logwood - various browns to black - you can get it from trapper's or some historical suppliers
Cochineal - reds - mix with walnut or logwood fro reddish browns
Walnut hulls - in general you need to make it strong and thick and leave the leather soak in it for a fair amount of time to get any real coloring
Turmeric - yellows
Madder root - reds
Coffee - dark roast biled strong makes nice browns (may not be "period" but it works pretty good)
Various barks (mostly inner) give good colors: i.e. willow gives reds to browns, oak bark gives browns
See more here - all of the materials are available on line from various suppliers
http://chestofbooks.com/reference/Henley-s-20th-Century-Formulas-Recipes-Processes-Vol2/Dyeing-Leather.html
http://www.museum.state.il.us/muslink/pdfs/dye_plants.pdf
BTW - braintan.com has some good info on the various methods of tanning including bark tanning - http://www.braintan.com/intro/intro.html and http://www.braintan.com/barktan/1basics.htm
The Book of Buckskinning 7 also has an excellent article by Mark Odle on traditional veg/bark tanning.
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Chuck, you are never "late to the game" with good information, thanks for the post. Good reminder about the neutralization using baking soda, many modern hobbyists in the reenacting community are never made aware of this step and ....... Well, you know what happens.
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You filled in a whole bunch of cracks in my landscape Chuck, and I sincerely thank you. I've been considering dying before I assemble the bag rather than after, as I did on this one. If I'm reading between the lines, that appears to be what you're saying too. Or did I expose one crack too many? ;D
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While I use the term neutralize I'm not quite sure that is "chemically" speaking accurate although it does foam and definitely helps dissipate the odor - the problem is being careful to not over do it since bark tan leather is and should be slightly acidic.
Brown Bear - it all depends, personally I dislike working pre-dyed leather, but there are times that it si necessary - IMO in the long run do what works best for you and the project. While there are wrong wasy to approach most anything I've found in general there is no single right way......
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Wouldn't Logwood stain fade to brown rather quickly? I sure ain't colorfast in cloth of any type. Might have to do some more experimenting to find out. Would one need to mordant the dyes like one generally needs to with cloth?
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Wouldn't Logwood stain fade to brown rather quickly? I sure ain't colorfast in cloth of any type. Might have to do some more experimenting to find out. Would one need to mordant the dyes like one generally needs to with cloth?
Logwood, as a dye, was considered to be one of the few plant dyes that proved to be colorfast to sunlight exposure. The same with the dye obtained from walnut husks.
If you go a hundred years or more you will find wide use of what are known as "mineral pigment" dyes on protein based goods, such as leather and wool. Basically the acid salt of certain metals which are then converted to water-insoluble pigments on or in the protein based goods.
There are a host of wee critters in nature that feed on such protein materials. Once impregnated with certain metals the wee criiters avoid it because the item becomes highly toxic to the wee critter.
In the case of the mineral pigment dyes they will sometimes use a tannin to change the final color. This sometimes confuses people with mordant dyes.
The use of vinegar (acetic acid) to produce mineral pigment dyes goes back to ancient Greece. Noted in 50 AD in Rome in the writings of Pliny, the Elder.
The first mention of mineral acids appears to date to around 800 AD in Arabian writings. By 1550 mineral acid production in London England had reached a point where the then King issued what is considered to be the first anti-pollution law.
Bill K.
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Wow! I hope all this info is as useful and interesting to others as it is to me!
I finally got time to snag snapshots of the bag that started it. Not the best light, but you know how it goes....
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fi185.photobucket.com%2Falbums%2Fx201%2FAKBrownBear%2Fvinegaroon0781.jpg&hash=56ae459831942113d4ac8d0e9ef96a0f485c8374)
Front of bag. The black spot on the flap is actually a hole that was in the hide. Rustic to me. Both seams on the 2" gusset have welts.
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fi185.photobucket.com%2Falbums%2Fx201%2FAKBrownBear%2Fvinegaroon0795.jpg&hash=9bb3e318c404d07b63b3129c210789b4482a4355)
Back of bag.
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fi185.photobucket.com%2Falbums%2Fx201%2FAKBrownBear%2Fvinegaroon_0784.jpg&hash=3581d3133ce5472e3c9792cfbcfa6ec55c35b866)
Front panel.
For purely practical gear management I like those two small buttoned pockets on my bags- The front has a 1" gusset and the back is flat.
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fi185.photobucket.com%2Falbums%2Fx201%2FAKBrownBear%2Fvinegaroon0779.jpg&hash=61c2a322c6faa417c392b86ab577de4d92045a81)
Closeup showing some of the cracking that was just starting when I applied TOW mink oil grease. I really like the "antiquing" effect it gives. The whole bag is pliable now, but time will tell. More grease may be required in the future.
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BB,
That is one great looking bag. I like the flip-side idea.
Laurie
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Thanks, Laurie.
It's not an original idea, but it sure works for me. I keep cleaning patches and anything flat in the back pocket, stuff that's not needed for actually shooting in that little gusseted front pocket. Together they free up the main pocket for stuff used only for shooting. Lots more room for a big hand that way, and far less scrambling through stuff for a load. Button closures aren't a problem because everything there isn't needed quickly.
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I think the finish on the bag looks good. The next time you make one, wet the leather pieces good before you sew them together and really work it over. That is, ball it up, twist it, pull it, roll it this way and that in order to get it good and wrinkled while it is wet and pliable. That will give it a nice used look without the risk of it cracking. I am told that you can also put the leather through a cycle in the washing machine to good effect. When all done, walk all over the bag with gritty shoes/boots. I have used sandpaper when my shoes didn't do the job.
Mark E.
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I would suggest that you might want to run "stuffing leather" through a search engine such as GOOGLE.
Normally tanned leather is rather stiff and hard. To make leather soft and supple they used to run it through a process known as "stuffing". The hides were thrown into a revolving drum. A non-oxidizable oil was added to the hides. The oil then worked its way into the hides as they tumbled. The oil makes the hides pliable. Acting as an "internal lubricant" in the porous structure of the leather. This also acts to waterproof the hides when they are made up into finished goods. During the 20th century a lot of mennhaden oil went into leather. At one time they also used "wool grease" (lanolin) for this.
The leather industry has gone through a lot of changes over the years.
We have all heard about smoking a hide. How the Indians would hang a hide in their living quarters and let the smoke from the fire contact the hide. The smoke being rich in creosote. Smoking a hide like one smoked a ham to preserve it.
By the 1920's the tanning industry came up with something they called Synthatan. Nothing more than creosote/creosol in a water emulsion used to "stuff" the tanned hides. Sort of a liquid smoking process.
Bill K.
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I would suggest that you might want to run "stuffing leather" through a search engine such as GOOGLE.
Normally tanned leather is rather stiff and hard. To make leather soft and supple they used to run it through a process known as "stuffing". The hides were thrown into a revolving drum. A non-oxidizable oil was added to the hides. The oil then worked its way into the hides as they tumbled. The oil makes the hides pliable. Acting as an "internal lubricant" in the porous structure of the leather. This also acts to waterproof the hides when they are made up into finished goods.
Bill K.
I appreciate the heads up. In a way that sounds like the oil/wax treated leather I traditionally build with for our wet climate up here. It's my standard for making camera bags and my "foul weather" shooting bags. It would be real interesting to come up with a way to produce something similar myself. Thanks!
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Logwood, as a dye, was considered to be one of the few plant dyes that proved to be colorfast to sunlight exposure.
Logwood was known as a very unstable and extremely light sensitive dye. At one point it was outlawed from usage in England and by name forbidden in Federal uniform regulations by mid 19th century, due to it's quick fading properties. Colorfast it most definately isn't. I've had logwood dyed cloth fade from dark gray to light tan within 14 days of repeated sulight exposure.
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Logwood, as a dye, was considered to be one of the few plant dyes that proved to be colorfast to sunlight exposure.
Logwood was known as a very unstable and extremely light sensitive dye. At one point it was outlawed from usage in England and by name forbidden in Federal uniform regulations by mid 19th century, due to it's quick fading properties. Colorfast it most definately isn't. I've had logwood dyed cloth fade from dark gray to light tan within 14 days of repeated sulight exposure.
It all depends on how you use it.
It was first used in England without a mordant. A decree was passed in 1581 prohibiting the use of it in that country. The reasons given were to foster sales of woad grown locally and to inhibit the use of an impermanet dye.
In 1619 a proclamation for Prevention and Restraint of the Abuses and Inconveniences Occasioned by Dying with Logwood was issued. In 1661 the law was lifted.
Logwood was used as a black dye in England into the 1950's and industrially in the U.S. into the 1970's. Used in the U.S. to dye typewriter ribbons and to color leather.
Logwood with mordants had been used on wool.
As a replacement for Indigo it was a total failure.
Bill k.
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Clark - Dying leather and dying cloth are generally two completely different things (in fact even dying cloth is different dependent on the dye) and comparing the two directly can be frstrating at best. For instance in general leather does not need a mordant since tannin is itself a mordant. On the other hand there are differences in tannins:
The Two Types
There are two types of tannin: Catechol and Pyrogallol.. By understanding when to blend these together, the expert tanner could reputedly create the appropriate leather for any need: hard and firm, mellow and soft, light or heavy. Until you are an expert and can even notice the differences, I wouldn't worry about it, but it is interesting to pay attention to as you tan.
Catechols (aka condensed) are more astringent and tan more quickly than the pyrogallols. They deposit a reddish sediment known as 'reds' or phlobaphenes. They make leathers of pink, red or dark brown hues, that are more 'solid'. They also create greenish-black spots on contact with iron. Mimosa, birch, hemlock, quebracho, alder and fir bark contain catechols. Oak bark contains both types.
Pyrogallols (aka hydrolysable) deposit a pale-colored sediment called 'bloom' (elegiac acid} which, if deposited in the leather, improves its solidarity, wearing properties and resistance to water. Hence they are favored for sole leather. They are also preferable for leathers intended for bookbinding, upholstery and other purposes where longevity is essential. The resultant leather is of pale color varying from creamy or yellowish to light brown. Pyrogallols make bluish-black spots on contact with iron and resist changes in pH value. Sumac, chestnut, oak galls and oak-wood contain pyrogallols.
source: http://braintan.com/barktan/2tannins.htm
The following article discusses the problems dying black using hemlock tanned leather versus oak tanned leather - this appears to be due to the differences in the tannins noted above and may shed some light on why import hides at times have problems when using vinegar black. On the other hand I've never had any real problems getting a decent to good black even with import hides and have never had the problems that Stophel noted......
http://www.jarnaginco.com/cmharticle.pdf
As for logwood and leather - yes it is generally good for browns as is, for black it takes a bit more - just one recipe from the past I have is:
"Boil a quantity of logwood bark in double it's bulk of rain water (i.e. water that hasn't been tainted with minerals) for two or three hours, then strain off. Add 1/4 pound of potash to 2 gallons of the logwood liquor."
Note teh use of potash - a base like baking soda. In fact baking soda alone (or other stronger bases such as washing soda or potash) will darken leather, but I find that used alone they tends to "burn" the leather too easily when not carefully applied and that can be just a matter of seconds.
Normally tanned leather is rather stiff and hard. To make leather soft and supple they used to run it through a process known as "stuffing". The hides were thrown into a revolving drum. A non-oxidizable oil was added to the hides. The oil then worked its way into the hides as they tumbled. The oil makes the hides pliable. Acting as an "internal lubricant" in the porous structure of the leather. This also acts to waterproof the hides when they are made up into finished goods.
Thanks for your info Bill and it's still called stuffing. There are in fact two methods generally used, hot stuffing and regular stuffing aka fat liquoring. In period some of the most common oils used were: fish oil, neats foot oil, and tallow - beef and sheep mostly, although hog lard (aka pig tallow) was also used.
re: neats foot oil - originally rendered from the shin bones of neats aka cattle. Since the 1930's though neats foot oil made in the USA can be made from other sources (mostly hog lard these days per one of the major the manufacturers) as long as it's meets a certain Mil-Spec standard.
The "problem" with all oils in leather though is over time they either get "pushed out" to the surface due to water, sweat, and other factors so the leather drys out and gets damaged. In fact most dyes, especially modern ones that so often use thinners such as alcohol, toluene, etc. dry out, stiffen, and crack after application and why re-oiling/condtioning is necessary.
these links have some info of interest as well:
http://www.jarnaginco.com/leather%20definitions%20index.htm
http://www.hermannoakleather.com/
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Chuck,
A couple of points here.
You mention Hemlock as a tanbark. When I did the reading of the tech books at work they mentioned that the tanbark of choice simply depended on where the particular tannery was located. Around here they usedChestnut as their first choice and then oak as the second choice. The bundles of tanbark were known as "shales" of tanbark. The tanneries in upstate New York used Hemlock simply because oak and chestnut were not common trees up there.
The bark of oak yields both tannic acid and gallic acid. In some acorn caps the level of gallic acid is very high compared to the level of tannic acid. In effects produced the gallic acid was considered to be about 3 times stronger than tannic acid.
The tech book described the process in a roughly mid-19th century tannery. The actual tanning was done usually in 4 "pits". The first pit had a weak tannic acid solution in it. Then as you went to tank #2, then tank #3 and finally tank #4 the concentration of tannic acid increased in each tank. If you soaked the hide initially in a strong tannic acid solution the surface of the hide would become very hard and it would be nearly impossible to tan deeper into the hide.
In the pre-1900's tanning process there was the dunging step before tanning the leather. That step added some coloring matter to the hide. And different tanneriers had different ideas of which dung to use.
Then the wood selected as the source for tannic acid added coloring to the hide. According to the tech book the hemlock used in New York state tanneries added a red coloring to the finished leather. The red coloring not being seen in oak bark tanning.
The tech book went into the dunging thing a bit. The hide picked up extra sulfur ions from the dunging process. This also helped the leather pick up more tannins in the tanning step.
Neats foot oil.
The original source for neats foot oil was the cushiony pads in the hoofs of the livestock. In the hoof is sort of a sack that would yield this oil. The pad acting to cushion the shock when the hoof hit the ground if the animal was running. Sort of like gel pads in a running shoe. Trouble is that a hoof does not yield a lot of ths oil.
You mentioned the use of "potash".
Leather, horn, wool, etc., are "acid" materials. Hitting them with a strong caustic degrades them. I once tried boiling out horn cores in a bath of water and potash, potassium carbonate. The horns became very brittle and fragile. When I dropped one on the cement walk it shattered.
Potash was one of the earliest exports of the American colonies. Due to the vast forests of hardwood trees. Know in international trade as "American ashes" for about 200 years.
The tech books did not go into great detail on this but I think that sometimes potash was used to partially saponify some of the oils or fats used to stuff the leather to make them penetrate into the leather better than if just used alone.
I never thought that the tanning process was so long and tricky until I read the tech books on the old processes used to make leather.
Bill K.
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Thanks Bill for the added info - yep and dunging or bating is still done although what they use for the process today I'm not sure. Hermann Oak Leather
(http://www.hermannoakleather.com/) shows the overall process they currently use and the bating cycle is used to re-acidy/remove the lime from the leather and to add enzymes.
For those interested in the historical aspects, here are a couple of 19th Century treatises on tanning and leather manufacturing:
the first is from 1813:
http://books.google.com/books?id=6_oGAAAAQAAJ&printsec=frontcover&dq=circle+of+mechanical+arts&cd=1#v=onepage&q&f=false
The second 1898:
http://books.google.com/books?id=UhAAAAAAMAAJ&pg=PA188&lpg=PA188&dq=%22the+leather+manufacturer%22&source=bl&ots=b5sPc_utzW&sig=MHkeuBzzxVLwqSZXZ4wsPGe5kic&hl=en&ei=phzrS4vMB4G6swOysaTNDw&sa=X&oi=book_result&ct=result&resnum=7&ved=0CDkQ6AEwBg#v=onepage&q&f=false
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Excellent links Chuck, thanks for posting them. In the first, "The Circle of Mechanical Arts", I'm sure everyone also noted the chapter on "Gun-making", a good article on the gun maker's art as practiced in England at the time. At that time, nobody did it better.
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In fact baking soda alone (or other stronger bases such as washing soda or potash) will darken leather, but I find that used alone they tends to "burn" the leather too easily when not carefully applied and that can be just a matter of seconds.
How about a diluted solution, Chuck? If the pH is kept to around 9 to 9.5, wouldn't that be low enough to allow a reaction, but still give enough time to apply a very mild acid to neutralize the burn?
Just as thought from someone most recently employed as a chemical water treatment specialist, does anyone ever check the pH of the solutions they use, and if so what are the ranges of both the acid and base washes used?
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There's so much GOOD STUFF in this thread, I wonder if there is some way to preserve it and keep it readily accessible for future reference?
Thanks to all who have responded, and all else who contribute. I feel like I'm going to school again, but I'm certainly paying better attention this time around! ;D
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Roaringbull...not to step in out of turn, but I will answer that in my experience,
even diluted caustic salt type solutions that are still strong enough to darken the leather, seem to penetrate the leather very very quickly, where the water evaporates as the leather dries, thus concentrating the salts which stay deep "in" the leather...eventually degrading the leather like salts etc usually do...as simple as it seems, its actually pretty touchy stuff when used on leather... To me it seems kind of like using a good though slightly wet pair of nice dress leather gloves to throw rock salt on a frosty lane before church on a cold Sunday morning...even if you only throw a few handfulls, and even if you throw it really fast, theres a good chance you will see serious damage to the gloves by spring time if not sooner... :o
thats been my experience anyhow, but maybe neutralizing it etc with different techniques would give better results?
TCA
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well I'm far from an expert but you make a great point with the salts...which could cause an exothermic reaction if you did try and neautralize it with a acid of the wrong type, or even rinse it with water.
Think I'll just stick with the time-honored methods!! ;D