It was out the other day, is it back?
Laser Cutter issues once more
This would be a good case study for handling chemicals, it’s something that we need to get better at.
Maybe we should have a hazardous chemicals induction.
Anything hazardous should show up in a RA, and approximate action should arise from that.
This is happening with screen printing where there are a range of chemical used.
But does not cover stuff that people use for a one off .
It’s a good point – COSHH guidelines should be the starting point for all ‘chemicals’ used in the space. We need to make that explicitly, and easy to do.
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It was working Wednesday haven’t been since.
I am confused. What would be a good for a case study? The zinc selenide is not toxic.
My point. …
But it does have a scary name
Then we could use table salt, which is actually toxic. It is also cheaper and easier to get hold of than zinc selenide.
But sea salt is not toxic it can’t be it’s organic.
What is interesting about the lens is that we guessed at it’s toxicity and it took years for someone to look it up .
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It is not harmless. Or rather, Hydrogen Selenide is the real danger, which is the product of the reaction of ZnSe with any acid (eg. like that in your stomach). It is toxic in very low concentrations ie. 0.3 ppm.
ZnSe safety sheet:
https://www.thorlabs.com/images/tabimages/Zinc-Selenide_MSDS.pdf
H2Se safety sheet:
https://www.chemadvisor.com/matheson/database/msds/00244337000800003.pdf
So take precautions. Don’t sand or scrape the lens to make it fit. Wear gloves when handling damaged lenses. Don’t lick your fingers! H2Se smells strongly of garlic/rotten eggs so you’ll know about it if it’s around.
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That is what I am talking about.
Looking it up is a fantastic thing .
An induction to help people look up stuff that is written in a unfamiliar language, and or a team of chemical techs who have at least "A level " chemistry or degree level would be better, to help people look stuff up .
Can anyone confirm that one or more of the existing lenses that we have are manufactured by II-VI Infrared? I am writing a letter to them asking them to cite their sources showing that it is not toxic, given that we have conflicting information and I have not so far managed to turn up any scientific papers on the subject of ZnSe toxicity. I will send it to them if we can confirm that one of our existing lenses did indeed come from them. I think I recall their name on the packaging of the replacement lens that we got last year.
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It’s more it’s decomposition into hydrogen selenide by the process of attempted digestion, surely?
If that reaction does in fact take place. But how is that in conflict with the post you were responding to?
I did post that link on Discourse a year ago here:
https://discourse.southlondonmakerspace.org/t/laser-cutter-broken-2/1751/26?u=andrew_d
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But nobody else was listening because it has a scary name.
All that I am saying is that we need to get better at this sort of thing , more like you.
If in doubt look it up
Pete can you ask someone in Imperial?