Did y'all know about MASKING?!

So I bit the bullet and got myself a Glowforge this past week. It’s not nearly as good as what we got at the space, but suits my needs until I can come back and fully utilize the space.

It’s nice having a machine in my office in the house and able to work on it whenever I can spare, which means that I’ve been trying a lot of different things to improve my laser cutting knowledge.

What I wanted to pass along today is masking.

I can’t believe that I’ve been laser cutting for many years now (since back when we only had Blue), and I never knew about it.

Basically, if you got some pretty thin Baltic birch, and you’re having to deal with a lot of edge burn/smokiness around the engraving - put a thin layer of masking tape (or paper transfer tape like I’ve been using) on the wood.

Here’s some I picked up on Amazon.

Make sure to not overlap, this particular one is the same width as the cutting area on my bed, so it works great.

then just smooth it out with a squeegee, removing air bubbles.

this is REALLY great for the side you are engraving, but if you want to minimize smoke/burn marks on the opposite side from the cut, do it on both sides.

you might still need to hit the back with some sandpaper, but it’s significantly less.

Just wanted to pass this along, give it a try and let me know if it helps anyone. Again, can’t believe I never tried it before.

Happy Lasering,


Well known technique. In fact, there’s usually a roll of butcher paper near Red Laser that is communal supply that you can use for masking. It has vanished during COVID… one of the folks who uses the laser professionally kept it supplied and liked sharing… I forget the man’s name.

Masking can also be used for paint and overlay techniques. One of my favorite tricks: Lay blue painters tape on your wood and cut your outline at about 85% speed. Peel away the interior of the tape, rub wood glue over the whole surface (exposed wood and remaining tape), then lay down a sheet of leather across the wood. Recut your shape on whatever settings work well for your leather. Then peel away the remaining painters tape… the leather bound to the wood stays, while the leather bound to the glue stays. You can create some nice inlays doing that. Obviously works for other substances besides leather.

Wow, wish I knew about it before! Maybe an “advanced laser cutter techniques” class would be a good idea for the upcoming year. Covering things like masking, hold-down pins, jigs, etc.

Question for you Stephen - do you mask both front and back? Masking the front seems to be great for preventing smokiness on the engrave, but the back seems to have more blotchy spots, so is it better to just mask one side vs both in your experience?

Have you washed your finished pieces? Just water, no soap – most of the “burn marks” come right off because they’re really just residual plywood glue.

I try not to use masks if I can avoid it because they can cause as many problems as they solve. But when I do mask, I typically just mask the front… I had too many problems with masks on the back trapping more heat and causing more scorching (or, at least, that was my diagnosis).

(The above comments are about wood… masking is important for cutting acrylic! Keeps the laser from reflecting back up into itself!)

Not a bad idea! Tagging @astc for consideration

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If you are going to finish the work piece, one way to avoid masking is to finish the top and bottom surfaces before cutting or engraving. This includes sanding/staining both surfaces if desired. With the right topcoat and using a damp cloth or good sponge, the residue will generally come off, but the topcoat at the cut edge could change color slightly. (always test your material and topcoats to see what/if it works for you) With a clear coat you can usually color fill the engraving without masking, if the color fill / solvent does not react with the clear coat. Fill (paint) the engraving, wait a few minutes (depends on the fill (paint) material) and wipe off the fill (paint) material on the top surface. Doing 200 pieces tomorrow. BTW - most glue will not stick to a clear top coat and some paints. (Test - test - test)

Staining before engraving seems awfully dangerous. Are you sure that it wont damage the laser? Or give off toxic fumes with the high heat?

I don’t stain or clear coat on the same day as lasering.

The Stain and Clear coat ‘cure’ during the ‘drying’ process and I do those processes the day, week or year before I engrave or cut the material. Getting a piece of wood ready to be used takes at least 2 days to get ready for the laser. One day to sand and stain, and one day to get the 3 coats to clear on to the material. The volatile compounds have evaporated or merged during the drying of the stain or curing of the clear coat.

If you read the label on acrylic or latex paint you will see a list of volatile compounds, but we have cured paint in the house and on projects.
The wood. plywood and acrylic we cut have ‘toxic’ fumes in the residue which we exhaust outside or is left on the material after engraving or cutting. When Staining wood, the Stain leaves a coating on the top of the wood and might penetrate a short distance into the wood. I do not believe there are compounds in the coatings that I use which will harm the laser. I have cut tens of thousands of pieces of stained and coated wood across 12 different lasers, on 8 different brands over 14 plus years and I do not believe I have harmed any laser while cutting or engraving stained and clear coated wood.

Do you cut plywood? Do you know how the wood the plywood was made or was treated before or after it was manufactured? What type of glue was used to hold it together? Any glue used to hold the veneer plys together is burned and vaporized during the cutting and engraving process, what type of compounds are created when running on the laser? Those could also be ‘harmful’ to the laser.

We do not get a MSDS or SDS sheet with the plywood to tell us what glue is being used, so we can’t guess the possible compounds that get created when the laser hits it.

Harlan, I’m sorry but I feel a little bit attacked in your last post. Yes, I do cut plywood, its a very common material to cut on the laser cutter. Maybe I’m misreading but I feel like your question in regards to that was a bit condescending when I’m just trying to look out for the space’s equipment and members. My intention in this thread was to pass along some information that might help people and now I feel extremely discouraged from doing so again. Your post was very informative until the last few paragraphs and I implore you to reflect on how that might come off as discouraging to a well meaning stranger.

@lukeyes I for one have never heard of this trick, so thanks for sharing! I haven’t spent that much time on the lasers, but I’ve done a little bit of leather cutting and engraving and I’m wondering if the same trick could work well on leather. I never much liked the scorching that I’d see on the edges and around the engraving. I’ll definitely have to give this tip a shot. Thanks!

I have been searching for an alternative to Eclipse Art Masking Tape. This is a 6" paper tape I was going to use for lasers. And I also want to check it out to replace blue painters tape for the CNC, for holding items down with CA glue. A single layer of tape would be better than multiple strips of tape. Easier, anyway. If it sticks enough for CNC… upcoming experiment.

I bought a 12" wide roll of blue painters tape like this: https://www.amazon.com/STIKK-Painters-Removal-Covering-Protecting/dp/B08C3ZKPC5/ref=sr_1_2?dchild=1&keywords=12"+blue+painters+tape&qid=1609206393&sr=8-2