Two questions for leather engravers

Lots of articles all through the Internet. Chrome tanned leather is extremely toxic.

http://www.leathersmithe.com/tanning-methods-and-the.html

https://nepis.epa.gov/Exe/ZyNET.exe/910185O2.TXT?ZyActionD=ZyDocument&Client=EPA&Index=1976+Thru+1980&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A\zyfiles\Index%20Data\76thru80\Txt\00000025\910185O2.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h|-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=hpfr&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL

I’m not a scientist, so may not fully understand the referenced articles, especially the PMC report, but in reading them there does not seem to be any relevance to laser cutting/engraving of chrome-tanned leather. The first two apparently deal with chrome-tanned leather contact with skin, while the third deals with waste products resulting from the chrome tanning process. From what I understand, of the two types of chromium found in leather, Cr(III) seems to be basically non-toxic, but Cr(VI) is certainly toxic and a carcinogen. The problem is, the articles don’t describe how a laser effects either of the chrome components of chrome-tanned leather and in what amount.

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Also know as hexavalent chromium - it’s released upon burning chrome tanned leathers such as in laser cutting or laser engraving. The amount varies depending on many factors. The cautious leather laserers prefer to avoid breathing it altogether.

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Well that settles it, the internet says so.

None of the citations you linked mention lasering or even burning the leather. They do point out though that the chromium compounds used in tanning are not the toxic hexavalent chromium compounds.

What they are exploring is the release of chromium compounds that through contact cause 1-3% of the (European) population to exhibit contact dermatitis. They also deal with exposure times significantly in excess of that experienced by any crafter lasering leather for projects.

They also rightly point out that chrome tanned leather is used in almost all consumer leather goods - you know, shoes, gloves, coats. That’s the exposure vector for contact dermatitis.

I hope since you’re so concerned about the toxicity of leather you do not wear anything made of leather and don’t permit your family or pets to do so either. Even your furniture or car seats could provoke a reaction so best to stick with fabric textiles.

Just because a small portion of the population exhibits some sensitivity (usually redness) to long term exposure to chrome tanned leather does not support dire warnings about the toxicity of lasering leather in a properly vented machine.

Just as most people don’t wrap their mouth around their car’s tailpipe and get toxic doses of CO and CO2 most people aren’t going to reach any significant exposure level lasering leather - it’s far more likely they’ll react to the clothes they wear (the #1 cause of chromium sensitivity).

Those folks generally know they’re sensitive and aren’t likely to be lasering it in the first place.

However, I’m always willing to review any curated data that might indicate otherwise. I don’t want to be leading my students astray. So if you find anything that links the combustion byproducts of chrome tanned leather with any illness or death, I’d love to see it.

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And not used in chrome tanning. See her first reference.

The air you breath in almost any city in the industrialized world is both toxic and full of carcinogens.

And really, if you’re a smoker all of this stuff pales in terms of risk factors.

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Sorry to contradict you but it sometimes is. Short of working directly with a trusted tannery there’s no way to know for certain, hence the problem.

"Chromium (VI) however is harmful to health and occasionally exists in leather. " The article also states that inhaling chromium (VI) is highly dangerous.

https://www.leather-dictionary.com/index.php/Chrome_VI_-_Chromium_VI

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And almost never is. To quote your source:

“Chromium (VI) however is harmful to health and occasionally exists in leather. It can come about due to mistakes in production or can emerge later in the manufactured leather. There is a risk of an allergic reaction to the end user.”

That risk was 0.2 to 0.6%. OMG how can we let children touch this stuff? Danger Will Robinson, Danger!

And

“These substances do not necessarily exist in chrome tanning processes, although they may arise depending on the method and the materials used.”

Except for the highly allergic

“The remaining allergy risk is almost irrelevant in everyday use of leather.”

Of course there is this:

“Many reports of chromium VI exceeding safe limits have been published in the press. However, none of the reports provide any details of damages or allergies caused.”

Of course, no product grown, made, treated or transported can be guaranteed to be free from contaminants or measurable amounts of unsafe or dangerous substances. Most people would be amazed at what is allowed to be in the water they suck out of plastic bottles (or their own tap) every single day. Or the cigarettes they’re puffing away on while worrying about hexavalent chromium exposure.

My point is not that there is no risk with any of this, but that dire warnings of toxicity and the scaremongering that results, especially for people new to lasers is irresponsible. Especially when the science says exactly the opposite.

Every class I teach has someone who is scared to death because they read something or heard someone say something that led them to believe this stuff is incredibly dangerous to themselves or the machine. They’re so focused on the danger they’re scared of doing anything. We see that in the forum all the time - people afraid to laser anything but PG, scared they’re going to break something. Unless we stop the misinformation they’re likely to go find some other “safer” hobby.

Personally I don’t give a rodent’s patootie if someone chooses not to use some perfectly good materials due to fear. It’s their creativity that gets limited. What I care about are definitive statements by perceived experts that are not backed by facts. And it really trips my trigger when the warnings cross the death & danger line.

Which you won’t be doing even in incredibly small trace amounts ** with a properly vented ** machine.

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Take whatever risks you please with your own lungs. When I was younger I idiotically used a blowtorch to shape PVC pipe without a respirator, inhaled silly amounts of acrylic monomer and slathered untold other bits of industrial art supplies directly on my bare skin. I’ve also had several “old timer” friends and instructors who thought a little exposure here or there was no big deal until they were overcome with assorted cancers. After my own cancer scare a couple years ago I’m no longer taking chances with my health or those I work with.

As for the assertion regarding limiting creativity - creativity often shines brightest when limitations exist and ingenuity comes into play. There are PLENTY of non-atomizing ways to work with chrome tanned leather, even with a laser cutter in your arsenal.

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Glad you didn’t succumb to cancer. I hope you’re well ventilated or don’t cut any acrylic now since those compounds are a trigger for your body.

I’m done now - people can read both sides and the details in all of the linked articles and make their own assessment of the risk as it might apply to them versus just seeing a standalone unsupported statement of doom.

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Very good conversation. My takeaway from this is that I am not going to worry nearly as much cutting leather as to whether it is chrome or veg tanned. It was just something I had read early on and went with it. Chrome tanned leather == verboten. Now I have opposing information and it is compelling.

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I have used Pool salt for this though not on leather yet. :slight_smile:

All this arguing over toxicity. The stuff I have read says that chrome-tanned doesn’t cut well, that it shrivels and comes out looking like bacon, whereas veg/brain-tanned cuts beautifully.

I also generally avoid buying products that have nasty manufacturing processes if there is a better, safer product available, even if it costs a little more.

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Yeah, I discovered that just touching chrome-tanned leather makes me break out in a horrible itchy rash all over my body, and I don’t even have sensitive skin. Nasty stuff!

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Is that for shoes, apparel and handbags too or just unfinished chrome-tanned leather? It’s really hard to find much commercially available shoes/jackets/ etc that aren’t chrome tanned. Wonder if there’s some post manufacturing treatment that’s used to prevent reactions or if sensitivities like yours are just out of luck in terms of shoes and things.

Unfinished leather is what did it…I hope it hasn’t sensitized me to everything else!

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