How to test for Vegetable Tanned Leather

Hey guys, I’ve done some searches and I’ve gotten a LOT of great information about WHAT Vegetable Leather is and that it is much better for our Glowforges than Chrome or Oil Tanned Leathers.

This past weekend I picked up a BUNCH of leather scraps from the leather vendors at Maryland Renaissance Festival, and I’d like to know how I can tell if each scrap is either Vegetable Tanned Leather or something else. The only thing I think I can do is to cut a piece and burn it with fire. If it produces a Blue or Green flame, don’t use it. If it produces a Yellow or Red flame, it’s most likely Vegetable Tanned. Is this correct? Am I mixing testing techniques (This might be a test for Chlorine)? Will cutting Chrome or Oil Tanned hurt my machine?


This might help.


Anyone who knows this for sure can correct me, but this is my understanding:

Cutting chrome tanned will not damage the machine but it does make some nasty, potentially harmful fumes.

I think you’ll be ok if you vent well.

Again, I may be wrong, but I believe dan posted a chrome tanned leather project way back. Seems to indicate that it won’t kill the machine.


I had that webpage, but unfortunately I didn’t see a test I could run to determine which kind of leather I have. Lots of good information about what tanning is and some of the actual process used, but it doesn’t help me determine what I have in hand.

Basic question, I have a piece of leather in front of me. What can I do to it to determine what kind of tanning process it went through?


It may not be definitive, but vinegaroon turns vegtanned stuff dark grey black almost instantly.

I am not sure if that will be conclusive, some other tanning methods might go black too, but from what I understand, vegtanned always will.

I tested it on a piece of known chrome tanned leather, and it didn’t go black. Darker, yes, but not black like vegtanned.


Oh good, I was trying to figure out what Vinegaroon was. I have Vinegar and Steel Wool, I can find some time to apply it. It might be difficult to see this change on some of the already black pieces I have. Thanks for the assist!


It takes a few days to cook, but when it’s done it’s amazing how effective it is. When I say it’s instant, it’s instant. As soon as the leather gets wet, it turns dark grey, and if you wait a few seconds, it gets deeper and deeper until it’s pretty well black. It’s actually really cool.


oh… I’m going to have to look this up more then. I didn’t realize you had to cook it (cook the vinegar with steel wool in it). I’ll try and figure out how to make this solution so I can use it, I just thought I had to spray some vinegar on the steel wool, and then rub it on the leather.

Learning all the time!


By cook, I mean be patient and wait.

It takes a couple days for the steel wool to decompose into the vinegar.

I just put mine in a corner and waited 3-4 days, stirring it about once a day. Then you strain out the remaining steel wool and are left with a brown vinegar-smelling liquid. It’s entirely unconvincing, I was like “this won’t work”. Oh yes it did.

That being said, most chemical reactions go faster with some heat… keeping it warm might accelerate the process, though I don’t know how much.


what do you use to apply it? rag, sponge brush, more steel wool?

Once I get home tonight I’m going to give this a go. It’ll have to cure in the garage to make sure the toddler and cat don’t start “exploring” it.


I just dipped the entire piece in the small takeout container I made the vinegaroon in.

You could apply it with a brush, I’m sure. I will say that it’s easy to see where different applications are made, you can’t “match” it. I dipped half, flipped, and dipped the other half. It was easy to see the two sides until I let the darkening really complete (about 5 mins).

So, in the end if you saturate it, I don’t know if it matters how you apply it. I’m a total newbie at this stuff though, so maybe someone with more leather chops (chaps?) will chime in?


I thought maybe you could smell, test the feel, or see how quickly dye/water is absorbed, but I guess if you don’t have anything to compare it to that wouldn’t help.

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My understanding is that the main problem is that lasering chrome tanned is some of it lasers poorly - so don’t spend your money, or get your heart set on, that supple, soft, beautiful and expensive side only to find out it doesn’t work. I would expect leathers from Renaissance Festival vendors to be predominantly, if not wholly veg tanned. Maybe some chrome tanned lining leather, but if it has any thickness to it probably veg tanned. Or maybe not, you never know.

As for the fumes, when I did the math, the potential harm seemed very low to me, but different people have different thresholds.


thanks, I’m fine throwing it in the GF as long it won’t hurt the laser. The stuff I got I think is termed “Garment Leather”. Basically it is the thickness of regular fabric, but it’s leather. I think that is about 3 oz leather? purely guessing here, VERY little experience working with leather


I’ve cut some chrome tanned without issue.


In that case it is probably chrome tanned. But do a small test run with it. At that light of a weight you’ll probably be good. It’s when you fork over hundreds of dollars only to find out you have to learn leather working with edged tools because its a mess when lasered that you…


I’ve posted a few times on this. (Hard to find on the phone.) There are two quick tests - a burn test and what kind of ash is produced and a water float test.

Both require you cut a piece off. But once you have a known sample of each you’ll be able to tell from the surface finish and the feel. (Since those tests are comparative, you need known samples or you won’t know if something is smoother or stiffer because you have no reference.)


I’m pretty sure that I’ve even read your posts on this, but I couldn’t find them with my search terms, and at the time I didn’t need the information, so it didn’t pop back out to me when I came across this.

For the Burn test, was I right in my guess? Red/Yellow flame veg tan, Blue/Green chrome tan?

I would like to hear what I should be looking for with the Ash and water float test. I have no issues cutting a scrap off of the scrap I bought.


Veggie will burn up and create a black or gray ash. Chrome will burn leaving a greenish ash

The water float test is done on a small strip placed in boiling water - chrome tanned will immediately curl up and eventually sink; veggie just floats there.

(I swear I’m going to pin this somewhere :grin:…but then I never do.)