Clear acrylic cracks and swirls?

Charl · Post by **Charl** » Fri Aug 29, 2008 6:55 am

Is the following normal for a clear acrylic stem? I know there has been talk about using cast acrylic and not extruded, do I perhaps have the extruded one?

Post by **KurtHuhn** » Fri Aug 29, 2008 8:37 am

This is one of those reasons why I HATE clear acrylic.

What you've got there is the remnants of drilling acrylic. It's stress fractures that develop due to the heat and internal pressures of chips against the sides of the drilled channel. This happens to both cast and extruded acrylic.

If you want to use clear acrylic you can minimize these by making sure your bits are sharp, sharp, SHARP. Use cutting lubricant, and drill small amounts at a time, clearing the chips regularly. When drilling, treat it like a metal, and spin your bit (or the acrylic if using a lathe) very slowly. Don't get impatient with it, and make sure you're use light pressure.

Charl · Post by **Charl** » Fri Aug 29, 2008 11:15 am

Thanks for clearing that up, Kurt. I think I'm with you on starting to hate clear acrylic!

TreverT · Post by **TreverT** » Fri Aug 29, 2008 2:24 pm

Another possibility is that the stem may have had an acetone-soaked cleaner passed through it. I discovered quite by unfortunate accident that acetone can cause some types of acrylic to instantly develop spiderwebbed stress cracks just from contact - I was cleaning up a handcut tortoiseshell acrylic stem and there was no alcohol nearby, so I swabbed the interior quickly with acetone. Three minutes later, I had a useless stem.

JHowell · Post by **JHowell** » Fri Aug 29, 2008 6:40 pm

True, or any petroleum solvent. I once accidentally splattered my BMW motorcycle windscreen -- evidently acrylic -- with gasoline. Although I cleaned it up as quickly and as well as I could, the next morning it was spiderwebbed with cracks. For that stem, though, it kinda looks cool. Probably a major yuck for the next guy, but it looks like some sort of plankton creature.

Frank · Post by **Frank** » Fri Aug 29, 2008 8:21 pm

JHowell wrote:For that stem, though, it kinda looks cool. Probably a major yuck for the next guy, but it looks like some sort of plankton creature.

True. Looks like a weird lab experiment. Just keep smoking it until your hands turn brown.

Charl · Post by **Charl** » Sat Aug 30, 2008 3:16 am

JHowell wrote:
For that stem, though, it kinda looks cool. Probably a major yuck for the next guy, but it looks like some sort of plankton creature.

True. Looks like a weird lab experiment. Just keep smoking it until your hands turn brown.

Not that a bit of yellow/brown twirls and swirls in a pipe stem will ever stop me from smoking!

Haven't yet had a chance to try acetone in the stem. My mad professor chemist friend hasn't been around yet, otherwise there would have been.