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  1. #1
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    Laser cutting PU leather... yes or not?

    So, as with much on the internet, half of the information I've found regarding PU leather contradicts the other half.

    I know that real leather is not a problem on the laser, I also know that PVC leather is a bad idea.
    On the other hand, PU leather... I find as many people saying that it engraves great (even Epilog) as they say you should avoid it.

    I have several PVC free leather supplier around, and one specifically says it's 60% Polyurethan and 40% Polyester (which I assume is the fabric the PU is bonded to).

    So what do you think? Is PU leather as bad as PVC leather? Or is PU safe?
    Any first-hand experience?

  2. #2
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    Re: Laser cutting PU leather... yes or not?

    No, you shouldn't burn any kind of polyurethane. The resulting fumes are extremely toxic, containing isocyanates and hydrogen cyanide gas - google Bhopal if it doesn't ring a bell). The reason you may not be hearing from people who have done it is because they're dead. Here's a MSDS: https://www.smooth-on.com/msds/files...lex_Series.pdf
    Andrew Werby
    Website

  3. #3
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    Re: Laser cutting PU leather... yes or not?

    Many thanks Andrew, I will definitively add it to the list of "avoid that stuff".
    Just surprised how avoiding lasering on PVC is common knowledge, but not so much about PU.

  4. #4
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    Re: Laser cutting PU leather... yes or not?

    Quote Originally Posted by awerby View Post
    No, you shouldn't burn any kind of polyurethane. The resulting fumes are extremely toxic, containing isocyanates and hydrogen cyanide gas - google Bhopal if it doesn't ring a bell). The reason you may not be hearing from people who have done it is because they're dead. Here's a MSDS: https://www.smooth-on.com/msds/files...lex_Series.pdf
    epilog, as other manufacturers, specifically list polyurethane as laser safe.

    the isocyanates and ‘hydrogen cyanide gas’ are at lower levels than cutting or engraving wood.

    It’s about as accurate as people wittering on about formaldehyde, when you get more from one apple than in a 300x600mm sheet of 3mm mdf

    Just listing chemicals without reference to the amounts and, more importantly, their constituency, is fear-mongering.

    msds sheets tell you what happens when you burn something in a self-combusting situation - i.e. light it, stand back. That’s not what happens in a laser. PU burns at 220-250C - the laser at the point of ablation is between 600-800C - none of the chemical processes are the same at that temperature

    PU leather is fine to cut and engrave as long as you, the operator, is not breathing in the output. Any decent extraction system will make it safe, for you. Whether you want to vent everything untreated is down to you. I think that, at least, a water bath is advisable when cutting plastics.

  5. #5
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    Re: Laser cutting PU leather... yes or not?

    Quote Originally Posted by ledaero View Post
    epilog, as other manufacturers, specifically list polyurethane as laser safe.

    [That would be alarming, if true. Fortunately, it's not. If you click the "full list" of recommended materials on Epilog's site, https://www.epiloglaser.com/laser-engraving/ there's no mention of polyurethane, as I suspected - companies are generally reluctant to poison their customers.]

    the isocyanates and ‘hydrogen cyanide gas’ are at lower levels than cutting or engraving wood.

    [Where'd you pull this "fact" out of? The only wood products known to generate these chemicals when burned are those treated with polyurethane or isocyanate compounds. Or do you have a source for this stuff?]

    It’s about as accurate as people wittering on about formaldehyde, when you get more from one apple than in a 300x600mm sheet of 3mm mdf

    [You eat your MDF, I'll have the apple...]

    Just listing chemicals without reference to the amounts and, more importantly, their constituency, is fear-mongering.

    [So enlighten us - how much isocyanate comes from burning a gram of polyurethane rubber, versus a gram of pine? Who is your "constituency" for this disregard of people's health?]

    msds sheets tell you what happens when you burn something in a self-combusting situation - i.e. light it, stand back. That’s not what happens in a laser. PU burns at 220-250C - the laser at the point of ablation is between 600-800C - none of the chemical processes are the same at that temperature

    [So you think they're entirely safe, then, as long as they don't reach a certain temperature? What temperature is that, exactly? Can you give us an accounting of all the chemicals generated. including their relative quantities, when a laser burns through a piece of polyurethane at 700C, for instance?]

    PU leather is fine to cut and engrave as long as you, the operator, is not breathing in the output. Any decent extraction system will make it safe, for you. Whether you want to vent everything untreated is down to you. I think that, at least, a water bath is advisable when cutting plastics.
    [That seems to be something of a retreat from the position you took at the beginning of this little screed. I agree; these chemicals aren't dangerous if nobody breathes or ingests them in another way. But most amateur laser-cutters don't filter their exhaust through a water bath. For them, taking some precautions against using materials with the most toxic combustion products would be a good idea, wouldn't you agree? Or are you set on taking a stand for people's right to poison themselves. and against the "fear-mongering" that advises them to avoid it? Ultimately, your safety is indeed "down to you" - be safe out there, folks, and don't believe every assertion that you read on the Internet.]
    Andrew Werby
    Website

  6. #6
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    Re: Laser cutting PU leather... yes or not?

    Quote Originally Posted by awerby View Post
    [That seems to be something of a retreat from the position you took at the beginning of this little screed. I agree; these chemicals aren't dangerous if nobody breathes or ingests them in another way. But most amateur laser-cutters don't filter their exhaust through a water bath. For them, taking some precautions against using materials with the most toxic combustion products would be a good idea, wouldn't you agree? Or are you set on taking a stand for people's right to poison themselves. and against the "fear-mongering" that advises them to avoid it? Ultimately, your safety is indeed "down to you" - be safe out there, folks, and don't believe every assertion that you read on the Internet.]
    Despite your attempts to belittle with the use of 'screed' and other diminishing words, you're still as wrong as you were with your first post.





    You're welcome.
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