In the past the chrome tanning process used to contain Hexavalent Chromium which was dangerous when cut with a laser. This is no longer the case as Hexavalent Chromium has been banned from the tanning process and has been replaced with trivalent chromium. Trivalent Chromium is completely safe when burned and does not cause any issues with health or to the laser.
This is only a quick summary, I will link the video where the professor of engineering from he university of SA gives a lot more detail.
I really appreciate your post. I have many chrome tanned leather bags from a company called Portland Leather, and their bags are made in Mexico, and I am reaching out to them to ask if they use trivalent chromium. I’ve been badly wanting to engrave a bag, but I choose to err on the side of caution, so I have not done so because most of their bags are chrome tanned.
In the posted video, he states that cutting polyurethane produces cyanide gas, which is toxic. Everything I’ve seen and read (even in this forum) says that PU is laser safe, but the guy in this video says it is not.
The info about the chrome tanned leather is great to know!
There is some polyurethane that contains PVC - PVC produces hydrogen chloride which is why it’s always good to have the SDS or know exactly what it is you are cutting. Buying products that are already marked as laser safe means offloading that responsibility to someone else - which is totally valid,
Not sure what the video said before and after the polyurethane comment, but it might be germane to the question.
Also - all polyurethane is bad for the lungs, so be sure to have good ventilation that doesn’t dump straight into an area where people are!
Hey it was banned in the UK not in the USA, however since then tanneries no longer use hexavalent chromium tan their products. However I would still buy from reputable tanneries that abide with the EU regulations and not from China if you plan on engraving/cutting chrome tan leather!
We may all be confused by the hideously complex way safety things are handled in the USA (because, when in doubt, we always pick the most absurdly complex and yet also useless mode of regulation); while OSHA does not ban hex chrome they do have a number of rules regarding it:
…in my past life some of these were exceptionally irritating, as we constantly had to prove our welding processes didn’t involve hex chrome (1926 Subpart D, Subpart J, Subpart Z).
Kinda like how we had to prove our laydown yard didn’t produce “notable” levels of silicon dust when the trucks drove on it, because god forbid anyone have feldspar in their gravel mix. Even though the roads they drove on to reach the laydown yard were basically 100% feldspar gravel.
…and yet at the same time the rules kinda made sense because I got to watch a guy die horribly because he entered a Wheelabrator when he shouldn’t have, because the guarding wasn’t sufficiently impassible. It is impassible now, even though that also makes it a PITA to service.
When you see a kid die horribly, and I mean really horribly it tends to re-set your thoughts on safety regulations unless you’re a straight-up psychopath.