Neoprene Foam

I have a customer that works with really tiny microphones. We use a .85 mm neoprene filler gasket between the surface of the microphone and the inside of the case to eliminate any airspace. They were cutting them out with a hobby knife and using a hole punch, so I decided to see if I could use the laser on them.

I used 500 zooms and 65 pews to get a good clean cut. The kerf was about 0.25 mm.

I got a lot of flashback on the first trial so I covered the crumb tray with blue tape and put the neoprene on the blue tape. The tape absorbed the flashback and both sides look identical. The cuts are clean and except for the corners I can’t really tell the difference between cut and lasered except that the laser cuts are straight. Manual cutting took about 45 seconds per gasket on average. The laser time for 14 units was 45 seconds.

There wasn’t much smoke, I saw a few sparks during cutting, and not much smell. I didn’t find any information stating that it wasn’t laser safe and several companies offering cutting services for it.


Thank you for using the proper units of laser measurement. Pure concentrated-light awesomeness.


Danger, Will Robinson!

I am not sure neoprene is safe. Reading the MSDS ( I see:

Fire Hazard: Flammable / Combustible under high heat and flame; can generate toxic, combustible fumes, carbon monoxide, chlorinated, hydrocarbon compounds, and soot.

Another sheet ( shows:

Hazardous decomposition products: Hydrogen chloride, Carbon monoxide, Organic acids, Aldehydes, Alcohols

And it appears the official name is Neoprene polychloroprene.

[Edited to add highlights.]


I think the kicker is the chlorine. hydrochloric acid is bad for both you and the machine.

Carbon monoxide can kill you and it is produced by most things we cut (wood acrylic leather) so you really want to make sure it is vented or filtered from the air you are breathing.

But the HCl can do a number on the machine, the vent, the filter and you.

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Odd it doesn’t smell. I cut some PVC wire insulation with a diode laser and couldn’t detect much smell. Perhaps the kerf is so small the amount of chlorine produced is minute.

I once filled my attic bedroom with chlorine as a kid when I tried to make hydrogen by electrolysis of water. To make the water conductive I added salt. I went away and left it not realising that it makes chlorine at the anode instead of oxygen. Didn’t kill me but did make my throat sore. That was probably a few litres of chlorine in a 10 square metre room.


You World War I reenactors take it too far sometimes


Always makes me :blush:


I will have to check the label. It may not be neoprene now that I think about it.

I’ve decided to become proficient in these techniques. You might do the same, if “funny, I don’t smell poison” isn’t a strong enough metric for personal safety.


That… Explains a lot…

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That’s a good system for determining the type of plastic. (May not be right in every corner case of plastic variations, but it’s good enough.) However, it doesn’t describe what plastics are laser safe.

I’ve been going by the little recycle symbols:

No symbol = don’t risk it.

“2 HDPE” is typically white plastic. (The “2” is written in the recycle triangle symbol.)
“5 PP” is typically a transparent or colored plastic, like amber pill bottles.
With both of these, don’t cut – it melts and may catch fire. Etching should (emphasize “should” since I haven’t tested it yet) make smooth surfaces rough, and transparent should become opaque.

“3 V” or “3 PVC” DO NOT USE! Poisonous and corrosive gas.

I don’t know about any of the other recyclable plastic notations.


Unfortunately, not everything that smells is bad for you, and not everything that is bad for you smells. In the Industrial Hygiene world, I have heard from folks who say “that smells terrible, it’s probably really bad for me” or worse, when telling someone that they shouldn’t breathe something in, they say “well I don’t smell it.” The joke in the IH world is “I’m glad you have a calibrated nose.”

In short - “your nose knows” isn’t a safe method to keep you healthy. Read the SDS and trust it.


Yes I know that but chlorine should definitely smell, so absence of smell means it must only be in very small quantities.


In my school days we were still making blue prints using the ammonia method. You knew when there was a mild leak, since we all know that smell.
But it got bad when there was a large leak. You walked into the blueprint room and as you took a breath it was like you were in a vacuum with no air to breath. So you slapped the emergency exhaust and stumbled out of the room before you passed out.
There was no smell at that point, just no breathable air to use.

I plan on being very cautious about what I am turning into vapor.

(Schools have better safety ratings these days than back then, but I still read about the science lab that goes bang now and again).

Disclaimer: On the plus side, after a strong whiff of concentrated ammonia and having all your sinuses flow onto your shirt, it will be a long time before you catch a cold. I think it is because the tissue where the cold virus attaches does not exist until some grows back.


Any success at hho since…?:slight_smile:

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Reminds me of the time as a kid i tried to make nitrous oxide (laughing gas). I had my mom pick up some ammonium nitrate from the garden store. I heated it in a huge beaker my dad had, and when it was full of gas I stuck my face in and took a big breath.

Unfortunately my mom bought the wrong stuff, and i inhaled a big breath of ammonia. That will certainly clear your sinuses! Needless to say, i learned a couple of lessons from that experience.


Chris (palmercr) left the forum a couple years ago. (So no help to be had there, sorry.)

Try not to blow yourselves up. :laughing:

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Yeah, like late at night, when I have a gastrointestinal issue and pull the blankets over my wife’s head. She refuses to believe it will clear up your sinuses.