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Jan 25, 2025 - 12:10:13 PM
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210 posts since 3/3/2008

I've been using an Omtech Polar laser along with a CNC router to make truss rod covers from various materials. A few weeks ago, I decided to try and see if celluloid (pearloid) was something that could be laser cut / engraved. My thinking was that I cut many other flammable materials (wood, felt, cork, acrylic, etc.) and the air assist keeps them from burning outside of the laser spot area (I think).

I was able to do some raster engraving with success (see attached Special Forces Truss Rod Covers - the right one is pearloid).

Today, I tried again with a standard Gibson bell design and it made quite a conflagration in the laser. Luckily, I watch pretty closely when I'm laser cutting anything questionable. This is from the same piece of pearloid with the same laser settings but for whatever reason, this time it burned pretty vigorously.




Jan 25, 2025 - 12:27:36 PM
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28473 posts since 6/25/2005

Celluloid is not only inflammable, it is explosive.

Jan 25, 2025 - 1:16:32 PM

11465 posts since 4/23/2004

Celluloid does burn vigorously! In the vintage fountain pen community, celluloid pens tend to warp over time. Straightening them requires careful heating over an alcohol flame. Too much heat and instead of a valuable vintage pen, you get a pile of cinders...

Youtube has a number of videos of celluloid burn tests (the 100 ping-pong ball burn is pretty cool). It isn't an explosion...but it does produce toxic fumes. Finely divided celluloid (dust) in the air can go up like a bomb...but then so can flour or wood-dust.

Jan 25, 2025 - 5:15:32 PM
Players Union Member

rmcdow

USA

1446 posts since 11/8/2014

Celluloid is basically gun cotton (nitrocellulose) mixed with camphor to plasticize it. You could try using either argon or nitrogen (from a tank) instead of air assist, and that might keep it from catching on fire.

Jan 25, 2025 - 5:24 PM

210 posts since 3/3/2008

I'll probably just use the CNC router instead. The challenge is that the kerf on the laser is 0.004" and the smallest cutter that I can comfortably run on the CNC is 0.020" and it's slow... I can get some more detail using a 60 degree v-bit but it's still not ideal

Jan 25, 2025 - 5:26:27 PM
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210 posts since 3/3/2008

Also, I just verified that nitrocellulose doesnt need an external oxygen source to burn so a non-flammable assist probably won't help much.

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