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Keep your Whisky away from your Flame Polished Acrylic
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PL1:

--- Quote from: griffindodd on September 21, 2012, 11:50:12 am ---My sexiness induces stress in all kinds of materials.

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Is that the explaination for Rodney's reaction (multiple times) in your build thread?   >:D


--- Quote from: rablack97 on August 06, 2012, 12:39:13 pm ---TROUSERS MESSED!!!!!!! :drool

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Scott
selfie:

--- Quote from: lilshawn on September 21, 2012, 11:47:20 am ---I think the issue is that the flame messes with the internal structure of the plastic, setting up an uneven pressure zone on the edge of the plastic (A mechanical stress). the alcohol induces a CHEMICAL stress...since the edge of the plastic now has an uneven MECHANICAL stress area, the alcohol is just compounding an already stressed area.

Once a craze is formed this creates a path so that the attack can continue internally and the crazing process  accelerates.

How chemicals induce a stress in plastics is still not fully understood, and it has been studied for decades!

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That is what I understand to be happening too.


--- Quote from: griffindodd on September 21, 2012, 11:16:55 am ---You can anneal acrylic by heating it to 180f and then letting it slow cool

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Spot on. Polycarbonate (lexan) needs to be "annealed" before thermoforming. The process is more accurately Drying than annealing.

Crazing is more an issue with flame polished edges than LASER cut edges. A higher powered LASER cutter can cut the acrylic at a higher speed which transfers less heat into the material than flame polishing. I regularly solvent bold LASER cut edges and VERY, VERY rarely have issues.
RandyT:

--- Quote from: selfie on September 23, 2012, 06:30:46 pm ---Crazing is more an issue with flame polished edges than LASER cut edges. A higher powered LASER cutter can cut the acrylic at a higher speed which transfers less heat into the material than flame polishing. I regularly solvent bold LASER cut edges and VERY, VERY rarely have issues.

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It depends on the type of material you laser cut.  Extruded acrylic will do the same thing when alcohol hits the edges.  Perhaps you are cutting the cast variety?  They use different base materials, and the cast variety is less susceptible to this phenomenon. 
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