<a href=showthread.php?s=&postid=15426815#post15426815 target=_blank>Originally posted</a> by insane
I have a bunch of 1/4" acrylic panels out in my garage from a store fixture display. Is there a way to tell if it is cast or extruded?
There's a few ways to the trained eye, ear, nose, and throat... but the easiest way is to measure the thickness and the uniformity of it. Extruded will be .236" (6mm) and pretty damned consistent throughout the sheet. Continuous cast materials are very consistent as well but they are pretty rare these days. Cell cast materials will vary from ~.210-.250".
If you look at the surface of the material at a very skewed angle, extruded will have extrusion lines that run in one direction only. Cell cast materials will not have this issue.
Also with most extrudeds, there is a propensity to mottling of the surface with lots of little "pock marks" on it.
<a href=showthread.php?s=&postid=15427214#post15427214 target=_blank>Originally posted</a> by troylee
Run a piece through a table saw if it melts its extruded.....cast will cut nice and clean sometimes it chips if it is cheap cast.....but 100% of the time extruded melts...
HUH??????? What??
If it melts, you're either using the wrong kind of blade or it's dull. Extruded should not melt at all when simply running it through a table saw. I have zero issues with it melting, pretty much ever. If it does start to melt, the blade gets replaced and the problem is solved
Chipping has to do with the saw blade (generally) and even the best acrylics will chip if you're using the wrong blade. The difference in hardness between cast and extruded is only a point or two so a difference in chipping should not be so significant that a layman could easily tell the difference.
And cast will melt too if the blade is dull so not a good indicator
James