plexi/acetone

[flyingmelon]

Has anyone that has made this mixture had the problem of pressure building up in the can? I just started making my first batch (about 2 -3 inches of plexi in the bottom of a new paint can covered with acetone) and when I let it rest there was a pressure build up that popped the top off the can. Am I doing something wrong? Did I miss a step in the making process? Or is this a normal reaction and I should not close the lid tight?

 

[Rifleman1776]

Methinks the real experts in this crowd can speak better to the issue. But, it is pretty certain that when you start mixing chemicals and put them in a sealed vessel you will get reactions that cause gas expansion or other, even more exciting, activities.

 

[rixstix]

I usually start with 1-2 sq inches of 3mm thick acrylic per ounce of solvent to yield a consistency just shy of medium CA. For me, any more yields a thick goo that I don't like. As for solvent, I prefer to use MEK instead of Acetone. MEK is slower to evaporate and seems to fog less when used as a finish. HOWEVER, read, understand and follow the msds. MEK is some bad stuff. Home Depot, paint department, top shelf, sometimes labled methyl-ethyl-ketone.

I just put the acrylic & solvent into a sealed rubbermaid container and shake occasionally over the next few days. Never had a lid blow off but then this stays in the shade in cool weather. We've been in the low 40s outside at night and the shop is in the low 60s.

 

[thewishman]

Haven't had that problem. I used a paint can the first time - a new can, but it was painted inside. The paint inside started to come off the sides. Now I make my mixture in a tightly sealed mason jar.

But, it is pretty certain that when you start mixing chemicals and put them in a sealed vessel you will get reactions that cause gas expansion or other, even more exciting, activities.

If the container isn't tightly sealed, your acetone will rapidly evaporate. The only exciting activities with this mixture, in over two years of working with it, are perfect finishes, which, to me, are VERY exciting!

 

[kirkfranks]

I have noticed this the past week.
I think it is just the acetone evaporating. I have a 1/2 full coffee can that had been sitting in my pressure pot sealed with the valve closed. On three different days I noticed that the pressure gauge did not really move off of 0 but if I opened the valve the pot would give a noticeable exhale.

I put the coffee can in the pot because in the past over a couple weeks time the acetone would evaporate enough from the coffee can lid that it would become very thick.