How to tell if it's really acryllic?

[LaserNOT]

Hidy. Is/Are there any way/s to tell if an object is made of acrylic? (Or "laser" engraveable) Material/s?

I engrave pocket & fixed blade knife handles. Most of the time it works swell. However, recently I ran across some "plastic" stuff that ruined the knife and I now own a very nice 5 pc set of knives, 1 with a messed up handle.
Picture a fine fresh sidewalk with very smooth cement not quite dry. Now, somebody takes a the back of a spoon and "carves" his name into the middle of it. You get the picture now....

In any case, I have another "unknown" plastic handle to engrave, and this is on a "family heirloom" type knife. I am really gunshy now and am just too scared to try this. It appears to be acrylic with some kind of "fake" backing to it but I just am not sure...? Just to answer another question while I'm here, Can/would you "rotary engrave" acrylic? I'm getting an old rotary engraver from a friend soon and could'would defer this job till that is done, (this week I think), if you think it would be better than the laser.

I love the way acrylic turns out and with a paint fill, it is just awesome material to work with, but now, I"M SKEERED!
Thanks folks
JT

[zax15uk]

JT,

I don't know a good way to check that isn't destructive, so not much help on a one-off item.

Rotary engraving of acrylic is very effective providing you have the correct bits. They have a different relief angle and are generally sharper to reduce heat build up and melting. You will likely get better results with the laser if it's actually acrylic, but if you aren't sure then perhaps rotary is the best way.

Zax.

[Josywales]

JT
My experience is a pin test. I find a spot that is not visible and if I can push a pin into the area or if it is easy to scratch then I assume it is not Acrylic. Acrylic is normally harder than most plastics and if you scratch it, it reacts different to plastic. I just about always laser Acrylic and if I am unsure I use the rotary but have had a few mess ups there too. A bit of a pain when it is a one off and no sample runs. Good luck with the heirloom.

[aussiejohn]

Hi JT,

Be very careful with old knife handles! Some of the old plastics, especially the Ivoroid (fake Ivory) ones, as soon as they reach a certain temperature, up they go in a smoking "fizz". I set one off a few years ago just cutting it with a hacksaw! Once it starts to burn, there is no stopping it.

Best of luck!

[garagefela]

Originally Posted by aussiejohn Hi JT, Be very careful with old knife handles! Some of the old plastics, especially the Ivoroid (fake Ivory) ones, as soon as they reach a certain temperature, up they go in a smoking "fizz". I set one off a few years ago just cutting it with a hacksaw! Once it starts to burn, there is no stopping it. Best of luck!

I once set one knife handle on fire and sort of assumed it was celluloid type material by the way it burned.

[Litografa]

Looks like it was very old knife as celluloid is prohibited for house-hold use since 1994 in Europe.
I think best way to recognize material is burn small quantity. Acrylic smell very strong with specific odor.

[aussiejohn]

Hi guys,
I think I have an answer, just follow the link
http://www.acousticguitarforum.com/f...p/t-65711.html

[Litografa]

John, thank's - really funny I am celebrating 44 today Sorry for offtop!