Full Version: 1/16" acrylic cracking

From: markh789 [#1]
 26 Jun 2006
To: ALL

hello, we seem to be having a real bad problem with 1/16" non-glare acrylic cracking or creating a "spider-web" effect when we insert braille dots. Is there any solution for this problem? Thank You

From: Puck (PUCKERBRUSH) [#2]
 26 Jun 2006
To: markh789 [#1] 26 Jun 2006

Hi,

I've never had this happen when making my ADA signs but I use engraving stock, clear/matte. Not sure if thats what your using or not.

Also maybe the raster hole is not deep enough for the bead. Just a guess.

Puck

From: RALLYGUY (RALLYGUY1) [#3]
 26 Jun 2006
To: markh789 [#1] 26 Jun 2006

Are you using a solvent based adhesive to attach them? If the acrylic is stressed (overheated) when the holes are cut, any solvent in the vicinity (including adhesives) can make the acrylic "craze". Cast acrylic has less of a tendancy to do this, but the key is to reduce heat at the cutting point.

Hope this helps....

From: markh789 [#4]
 26 Jun 2006
To: RALLYGUY (RALLYGUY1) [#3] 26 Jun 2006

We sprayed the signs with a matte finish after inserting the braille dots, would it be possible that the spray could have caused the acrylic to crack?

From: markh789 [#5]
 26 Jun 2006
To: Puck (PUCKERBRUSH) [#2] 26 Jun 2006

Thank You, I will try the engraving stock, it is probably much more forgiving.

From: RALLYGUY (RALLYGUY1) [#6]
 26 Jun 2006
To: markh789 [#4] 28 Jun 2006

Yes it could...any solvent based product in an area where the acrylic was "stressed" (heated up) will cause crazing. The fix is in not stressing the plastic, or in using a product that isn't solvent based. (impossible in this case I'm afraid). That means you have to do whatever you can to minimize heat when cutting the holes. either cutter speed, engraving speed or the tool sharpness......There are plenty here that can help you on that....I am familiar with crazing on acrylic from working with flame polished edges and screen printing....

I don't know if there is any way to reduce the heat enough to eliminate your problem.

If the cracking appearing after you apply the matt finish....I'm pretty sure that's the cause of it.

From: Jim (PUZZLEHEAD) [#7]
 27 Jun 2006
To: markh789 [#5] 28 Jun 2006

I have had this same problem with the reverse engravable Ultra-Mattes from Rowmark. Fortunately it has only happened a handful of times and hasn't happened to me in at least 5 years. It wouldn't happen right away, but when I came back in the morning, many of the signs looked like someone had taken a hammer to them My only guess is that it was older, more brittle material. I gave samples of it to Rowmark and Johnson Plastics, but of course they had never heard of this happening before. I don't have any solution for you except to try a slightly larger engraving cutter or use some acrylic from a different source. I definitely prefer using Rowmark's ADA alternative plastic whenever possible, but the majority of the time I use the reverse Ultra-Mattes.

From: Angie [#8]
 11 Jul 2006
To: ALL

Cracking of the material after inserting the Rasters into the holes is what is called "crazing." This is the result of using an alcohol-based or petroleum based cleaner or paint on the Braille. Alcohol makes all of the imperfections in the material expand and cracking results. Make sure to use a non-alcholic based cleaner when cleaning a sign.

Angie
Accent Signage Systems, Inc.

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