I am in the process of learning this as well.
So far what I have picked up is the veg leather (tooling leather) tends to be stiff and hold it’s shape.
The chrome tanning tends to break down the fibers of the leather and make it softer.
So the leather they would tend to use in Upholstery would mostly be chrome tanned as it is the soft stuff that people would tend to like to feel.
A good read:
Correct about stiffness, but there are tanneries trying to make veg tanned leather more like chrome tanned so who knows. When someone on a leather working forum, who is into tooling or wet forming leather, runs into it they complain about it being too floppy. If the glowforge takes off with a new breed of leather workers, and fashion grade veg tan leather becomes the goal, I have no doubt the veg tan traditionalists will view the launch of the glowforge as the day a new evil arose in the universe.
Tell me about it.
http://www.tandyleather.com/en/product/milled-double-shoulders
Looks like it might come down to the burn and smell test.
@samantha, one thing it’s important to know is that pretty much all brightly colored leather is either chrome-tanned or it has a paint-like coating on it or both. I’ve sadly learned that both the chrome-tanning chemicals and any coatings can do nasty, unpredictable things to your laser or in your laser, so I recommend not making a big investment in anything with a lot of color. Stamped patterns in veg-tanned leather are fine, but if your leather has any color other than natural, brown, or black, the hide’s laserability is highly suspect. (Of course, being natural, brown, or black is no guarantee that it’s safe or usable, either.) If you’re buying from a leather supplier, they should be able to tell you the tannage of any leather you’re interested in before you buy.
BTW, it’s not that you necessarily CAN’T laser chrome-tanned leathers, but you’ll want to seriously consider your safety and test small cuts on anything you go ahead with. Oily leathers might boil and shrivel up on the cut lines, smell horrific, release toxic fumes, or something else. Or, in the case of very thin chrome-tanned leathers, you might find that the cut and fumes are just fine.
I’m planning to play around a LOT with leathers, and some possibilities include lightly burning cut patterns into some leathers that can’t take full laser cutting, and then cutting them out by hand, as well as heavily coloring some veg-tanned leathers after I’ve safely cut them in the laser. Another very cool way to play with leather will be to Glowforge stamps out of Delrin and then emboss veg-tanned leather with them.
Note though that you can get brilliant, bright colors by dying veg tan after you laser it, which is what we do - it’s not terribly hard and the results are stunning. And my laser-made belt was veg-tanned then black-dyed after cutting, and has been showing zero color wear for nearly two years. So it’s durable too.
The forums at Leatherworker.net are filled are very comprehensive for almost anything you can think of regarding leather.
I’m not very knowledgeable in leather, but that should be veg-tanned, any “tooling” leather should be, they also use “oak tanned” in place veg-tanned as well. I ordered a couple 10lb boxes of black & tan veg remnants from their tandyleatheroutlet store. I ordered a low grade side as well.
So what will be the workflow for engraving (not cutting) leather - I imagine that leather might respond to the laser differently from sample to sample - how is that accounted for? I understand conventional systems are dialed in using a test sample, but I don’t know if similar functionality is built into the GF app.
Haven’t heard as yet anything about including a process such as you describe. All of the responses from the company so far have indicated that you can characterize the material yourself and save the settings for later use. Materials vary to much. There will be no automatic characterization of materials. Very early on there was discussion about automatic characterization but the company dropped that idea before pre-order began because it didn’t work as well as hoped. I guess it’s possible they could give you a starting point to test from or a standard characterization process. Materials that the company will eventually sell are controlled and have been pre-characterized. But it might be some time before that store is up and running. Also unknown as to whether it would include materials such as leather.
At this point that is a task left to the user.
Is air filtration prudent for cutting various types of leather, even if it’s being vented outside? I’ve heard two things that lead me to that question: 1) I’m told that laser cutting leather is unpleasantly smelly, 2) some leathers such as chrome-tanned might produce toxic by-products when laser cut. (BTW, that’s a bummer about the health and safety issues with chrome-tanned, as it’s one of the dominant leather types out there).
Simply venting the GF outside simply moves issues 1 and 2 to the other side of the window, and now the neighbors become unwilling participants. My original understanding was the air filter should be used if one can’t vent to the outside, but should you also consider adding an air filter if you’ll be cutting leather?
If you’re not going to be venting to somewhere else (outside being the most popular choice) you should get an air filter. An air filter costs more and has a filter that eventually has to be replaced - arguments against. It filters particulates plus the activated carbon portion will bond various things. Does carbon bind with hexavalent chromium, the result of the chromium III used to tan the leather being incinerated, I don’t know but there are chemists on this board who may be able to provide an informed opinion. The OSHA regulation for hexavalent chromium is an eight hour weighted average where the amount of hexavalent chromium is not to exceed five micrograms per cubic meter. By my calculations a glowforge will definitely exhale more micrograms of vaporized leather than the OSHA standard inside an enclosed room. For a cut of pretty much any length. How much of that is dead cow/pig/goat/sheep/deer/stingray vapor and how much is hexavalent chromium, again I don’t know, but it is going to mainly be meat. When vented outside where there is a lot of cubic meters of air and wind blowing it all around you and the neighbors are going to be fine. I believe I read that the real health issue of chrome tanned leather, besides pollution from tanneries in countries with lax regulations and/or enforcement, is when people burn scraps as cooking fuel/heating fuel. Factor in that chrome tanned leather doesn’t cut well under a laser, so it won’t be happening much, and I don’t see it as much of a problem.
So the nasty bits that get vaporized are a small fraction of the total effluence, and once vented outside will get diluted dramatically further. I can picture this being a non-issue for rural and suburban settings - not so sure about a crowded apartment or condo setting.
I’ve observed that the large air cleaners that laser cutter companies use at trade shows don’t stop everything. I can smell if they’re cutting wood from 30ft away. Fortunately for me, that evokes positive childhood memories of camping trips. I’ve been told I won’t have the same feelings around the smell of laser-cutting leather, so venting outside seems like a priority for working with leather.
So there’s all kinds of leather (veg-tanned, chrome-tanned, rawhide, cow, pig, kangaroo, etc.), and I’m hearing they all cut differently. Alas, the terms I hear are very subjective: “like butter”, “cooked mess”, “shriveled like bacon”, and so on. The picturesque speech is certainly fun to read!
Photos would be really helpful here. Could GF and/or those that have tested laser cutting various leathers post actual photos of the results? I don’t mean cleaned-up marketing photos - I’m talking close-ups of just the cut/engrave, and in particular a rogue’s gallery of the “disasters” would be really-really helpful - documenting how things go wrong is often the most instructive. Thanks in advance!
That would be cool. Keep in mind, though, @gdmccormack, that the leather types you listed actually exist as combinations of ingredients and treatments–almost infinite combinations. Here’s what you deal with on each piece of leather:
Species: cow, pig, kangaroo, deer, alligator, sting ray, salmon, etc.
Age or type of animal: bull, calf, doe, etc.
Cut: whole hide, side bend, belly, etc. (see below)
Tannage: veg-tanned, chrome-tanned, alum-tawed, oil-tanned, brain-tanned, some mystery combination thereof??? such as latigo (veg+chrome) and bridle (veg+oil), etc.
Treatment: nubuck, freezing, ironing, sandblasting, etc.
Colorant: none, oil-based, vegetable dye, wax, alcohol-based, acrylic-based (many of which can be either a penetrating or surface treatment), etc.
Finish: none, carnauba wax, beeswax, acrylic spray, etc.
I think Glowforge is planning to sell materials, and I’m sure they would be able to guarantee the composition of their leathers. Speaking from experience, when you buy from a leather factory, you also have a good chance of being told the truth about what you’re getting, though if you get a new sales employee, you’re mostly getting good guesses. When you buy from a retailer like Tandy or craft stores, your chances of getting any real information about the composition drop dramatically, except when you buy rawhide or the simplest veg-tan stuff that’s meant for tooling. When you pick up a cool jacket at the thrift store or a sidewalk couch, hoping to upcycle them, you’ll have very little clue, and the default guess should be chrome-tanned.
So, if we’re going to do a database of leathers (which I think is a STELLAR idea, we should have the tester note everything they know about each sample (including source), all the settings they used, etc. I think the community would get the most benefit from tests of common leathers from known dealers (veg-tanned natural-color kangaroo leather in the K-Craft line from Packer Leather, Tandy’s split pigskin garment suede, etc.). That way, people can have consistent results and be able to order online with confidence.
@morganstanfield You kick butt and chew bubble gum!
@morganstanfield, thank you for that background, hopefully we’re off to a good start! I understand the type of leather will drive the behavior under the laser beam - what I’m struggling with is the language that describes what happened when someone tried to cut or engrave a particular type of leather. Pictures are worth a thousand words…
Just my bias, but I’m particularly interested in what doesn’t (subjectively) cut well and why - and when someone says don’t even try, then it gets even more interesting! “Shrivels up like bacon”, isn’t necessarily a bad thing, if that’s the effect you’re going for. Shriveled-up bacon can still taste pretty good 
Agreed–I’m all for having the photos be part of the database.
One of the reasons we felt we had to get into the materials business is because the liability for us speculating about what a given vendor was selling was just too high. We had too many experiences of a retailer selling X one day and identical-looking (but not lasering) Y the next. Or getting material from two locations that both said they were the same thing (3M adhesive, for which an MSDS was readily available) only to have them arrive and it was clear that one or both was lying, because they were visibly different from each other.
TLDR is that we’re going to spend our time making sure the materials we sell are awesome, safe, reliable, and work perfectly, and we won’t be in the business of characterizing others’ materials.
Then sometimes we’ll forget and engrave titanium sporks. More of a guideline than a rule, I’ll grant you.
To what degree will GF enable owners to characterize their own leather? Can we run test cuts/engraves, experimentally identify optimum power, speed, etc., then apply those customized settings to our own material?
