View Full Version : Is it OK/normal to have water created while engraving?

John Edgerton
12-14-2011, 5:03 PM
Hi folks, I'm new here so this is a first post. I've just gotten started with engraving and yesterday while cutting some 0.1" clear acrylic, I noticed droplets of water on the workpiece. I don't think it has anything to do with the acrylic as I have seen what I now believe was water while cutting plywood. At the time, I thought it was sap.

The best I can come up with is that the water is coming from the air pump that supplies the air assist. After all, it is a compressor and compressing air will result in moisture coming out of it gaseous state to liquid. Am I right on this? If so, what should I do about it? I don't know a lot about all of my equipment yet as I purchased it as a turn key system. Here is what I do know:

Epilog 35W Legend 24TT Laser
Penn State vacuum system with 4" inlet and outlet (specs unknown but very loud)
Gast air pump (model unknown at present)

Comments please.


Chuck Stone
12-14-2011, 5:27 PM
You'll want to get a water trap for the air hose. They are not expensive and can be
found at most hardware stores.

David Fairfield
12-14-2011, 6:26 PM
Yeah that's coming from the air assist. Do like Chuck says.

Dee Gallo
12-14-2011, 6:54 PM
Ditto what Chuck said and what Dave yeahed. Water trap AKA "moisture trap" in airbrush speak.

Richard Rumancik
12-15-2011, 9:34 AM
John, if you continue to run with moist air you are putting your lenses at risk of cracking so I would solve this as soon as possible. You can get a $10 inline desiccator but I would suggest that a better solution is warranted. In any event there are some past posts on the subject.

Bill Cunningham
12-15-2011, 10:07 PM
Don't panic too much, but the water could be coming from the acrylic. Acrylic will absorb water over time, so it stands to reason that it will give up the absorbed water when heated.. One of the reasons laser engraving plastic will lay funny on a humid day..


Richard Rumancik
12-16-2011, 10:02 AM
Although there may be a small amount of moisture in the acrylic, I would have expected any moisture to be vaporized and drawn into the exhaust stream rather than condense on the part. To condense there would have to be no air movement. John thinks he is seeing moisture generated on wood as well. I would still lean toward the compressor as being the culprit.

John Edgerton
12-17-2011, 12:35 AM
Thanks for all of the good suggestions. I will look for threads on the subject to study it more thoroughly.


Rodne Gold
12-17-2011, 12:47 AM
If your air assist does not go past the lenses or mirrors or pressurises them , then the moisture is not an issue.

Greg Bednar
12-17-2011, 10:54 AM
Is it OK/normal to have water created while engraving?

Definitely NOT if you're cutting compressed cellulose sponge!

David Fairfield
12-17-2011, 10:58 AM
If you're cutting paper, or a porous material like wood, you don't want water spraying from your air assist. Because it will ripple paper and cardstock, and get mixed with smoke soot and make ugly stains, too.

Michael Simpson Virgina
12-17-2011, 1:20 PM
When you get a water trap, (IE a must huve with Air assist) make sure you drain it from time to time. In the summer I have to drain mine every couple months. If you dont drain it, you will see the water drops once again.

Richard Rumancik
12-18-2011, 9:49 AM
If your air assist does not go past the lenses or mirrors or pressurises them , then the moisture is not an issue.

I forgot that the Epilogs don't pressurize the lens assembly like the GCC - I think it is just a liitle tube that shoots air at the point of cutting. So the lenses would not be at risk in the air is not directed at the lens.

Personally, I prefer lasers that pressurize the lens area and makes the air shoot straight down coaxial to the beam. The pressure keeps contamination off the lens and the coaxial air steam will clear the kerf better. This is more like how an industrial metal-cutting laser works. Actually I think more development should be done in this area to improve debris removal by designing better nose cones. In an industrial laser the nose cone is a pretty important component as it is essential to direct the gas stream properly to remove molten material. In the GCC design the hole is really too large to keep the air velocity high. I'm guessing the large hole is required because it is more tolerant of misaligned optics.

Cathy Wilson-Daly
02-15-2012, 5:48 PM
I usually raise acrylic a little above the bed before I cut it. I put it on top of overturned staples. I never really saw anything odd. I put the acrylic directly on the bed to make a jig and on the bottom side of the acrylic there was what looked like moisture. It was pretty sticky though. I never saw it when cutting anything else, like paper which I always put directly on the bed. Problem or normal or the same as described earlier in this thread?

Rodne Gold
02-16-2012, 12:34 AM
It's residue from the Acrylic melt, increase your air pressure on your air assist , if you don't have air assist , add it if you gonna cut acrylic a lot.

Cathy Wilson-Daly
02-16-2012, 1:57 PM
Thank you, I have air assist I'll try increasing the air pressure.