Liquid coming out of cut on acrylic

[Scott Shepherd]

Okay, here's one for the brain trust to help me with. I was cutting some 1/4" thick blue acrylic this evening. I had removed the paper from one side and applied adhesive to it (sheet of it), and I left the paper on the top.

Using air assist and an air dryer going into the laser, I noticed as it was cutting, there was a drop of blue moisture getting pushed across the paper near the cut. I freaked out, stopped the machine and immediately checked my air dryer to make sure it was plugged in and working. All things were good. Dryer is working, clear air tube to the laser was clear and no signs of moisture. Removed the lens assembly. No signs of moisture. So it's good clean, dry air coming into the laser.

I start it up again and watch close and it does it through all the rest of the cutting. I've never seen that before. Any ideas on what it was? I suspected it was the adhesive from the paper on the top, but I've cut plenty of colored acrylics and I've never seen that.

Any one else seen it? Know what's causing it?

[Bill Cunningham]

Acrylic will absorb moisture from the air.. The laser heat was probably just releasing it.. Or your acrylic was a true 'blue blood bleeder' :D

[Anthony Welch]

I've notice when I raster clear acrylic w/air assist on, here in humid Mississippi, it starts spitting out water and mixes with the dust from the rastered acrylic and turns cloudy.

Anthony

[Richard Rumancik]

Because acrylic cuts by vaporization, you generally don't see any solid or liquid residue as the acrylic gas immediately gets mixed with air and goes up the exhaust vent. And normally the gas is pushed through the back (underside) of the sheet of material (providing that the beam penetrated fully).

Is it possible that some vaporized blue PMMA (acrylic) condensed on the surface creating a blue liquid droplet of PMMA? Under the right circumstances, temperatures, humidity, etc it seems possible that that could occur. So maybe it was just an anomaly that the conditions were just right for a puff of PMMA gas to condense on the surface into ball. Just a guess . . .