I have been using Baltic Birch plywood and laser engraving on it, which works great. The issue I am having is that I coat the plywood with Table Top Epoxy after the engraving and keep getting bubbles coming up from the engravings.
I am not sure if I have this post in the correct category, but I am curious if someone may have run into a similar issue and if so, what is the best method of preventing it from happening.
Thanks in advance.
Rick
What they usually do is flash it with a torch.
This brings all the bubbles to the top.
Some techniques:
- For bubbles at the surface using a heat gun or propane torch should break the surface tension enough to get rid of the bubbles
- For deeper bubbles this may be a problem of too many bubbles being introduced into the epoxy itself. Try avoiding this or using a vacuum chamber to reduce the bubbles before the pour
- If bubbles continue to come from the engraving portion then try sealing the engraved surface with a thin coating then applying on top of the pre-sealed surface
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Thanks. I have used the torch, which gets rid of them instantly but once you walk away they return. I have kept doing this until the epoxy is pretty well set but then I get little divots on the surface where the bubbles burst.
I have tried using a thin coat to seal which works sometimes but it is just another step with something that I wouldn’t think needed to be so difficult.
So you’re saying there are new bubbles being formed from air drawn-in through the engraving? If so, not sure how you’d get around it other than changing materials or pre-sealing with something else. Perhaps sealing with super glue would be quicker and easier especially if you use an accelerant.
Great idea with using super glue. I will give that a try and post the results.
Be aware super glue is slow to cure in the open air. It can secure a finger long after the coating is applied.
I use Varithane Water Based Gloss to seal my wood items. Seals in the carbon too.
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I use the same techniques PY mentions. I don’t bother degassing the seal coat, tho. I agitate it so much working it into the crevices that it’s pointless. Besides, most soaks in.
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There are accelerants that are sold with super glue that basically make it instant cure. Crazy stuff.
What’s the cure time on this? I’ve meant to experiment with this specific product.
Depends on coating thickness, humidity, temperature, etc. You know the game. When “used as directed”, the label says “dry to touch in 30 minutes, recoating after 1 hour”.
On baltic ply, it soaks in and it touchable in about 5 minutes. I give it a second coat, put it in front of a fan, and it is completely dry in about 30 minutes.
If you want a gloss finish, the can suggests 4 coats.
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If bubbles are coming through the engraving area, I would probably try and seal it with some clear acrylic spray, assuming your are masking the wood prior to engraving. Super glue can dry kind of white, so it might not be the best for sealing an engraving. Just my thoughts.
I just use the same epoxy for sealing. I mix up a small batch, work it in, let it sit for an hour, blow out the excess with air, mop up the mess, let it cure to tacky, then do the big pour.
Takes a little longer, but I don’t worry about adhesion or interactions.
I think that this is a good plan and I will give it a try.
Thanks for the help.
Seal the piece with a clear poly finish or a clear spry enamel first. should help
I do make river tables and some with laser engravings. I stain and then use polyuretnane on top. Then I always do a seal coat and pop those bubble. You can do a small area to stop the bubbles many times until the bubbles stop. Then do a flood coat. If you are not doing a stain, then just use oil poly a few times, then a seal. You also didn’t mention the size of the wood your working on.
Tim,
Thanks for the input. I have some water based polyurethane spray that I was thinking that I would try.
The carved maps I make are either one or two sizes: 11 x 15 and 18 x 24 inches. The material is baltic birch plywood, though I don’t think that that matters.
Rick
I used to get the same issue solved by applying a coat of wood glue on the whole project it dries clear and can not be seen once coated with epoxy, just make sure you work it into the engraving so as not to miss any spots.
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It’s because ply is full of minute air holes, i had the same problem.
kept using the heat gun on it for ages, gave up in the end.
different types of wood act differently depending on the grain.
Normally (on real wood) it’s just a light coat to seal, then finish whatever you were wanting to do.
I am not an expert but after doing many tables, some wood will have more bubbles than others. I did engrave a birch door skin as it was cost effective. Thats why I alway do a seal coat at least once. Maybe twice I lucked out.
I use Botecote epoxy from Boatcraft Pacific. They have a diluent called TPRDA which reduces viscosity and surface tension of the epoxy and helps it penetrate. I apply this in the first, very thin coat with a metal scraper to help force it into the wood and expel the air. Makes the total epoxy finish be part of the wood instead of just a surface coating.