Resin doming wooden items

[Joe Hillmann]

Can anyone give me any pointers on doming wooden engraved items?

My main questions are.

...How do I prevent air bubbles? The instructions say I wood items may need to be sealed with one or two thin coats of resin before putting on the thick coat. The problem with that is it takes 5 hours between coats for it to dry. Can I use a sanding sealer or clear lacquer for the seal coats, or will they react badly with the resin?

...Can I dome over color filled engraved areas? The color filling will be done with spray paint or brushed on acylic paint. Will the domeing resin react with the paints and cause bleeding or some other problem?


If it matters the largest items I plan to dome will be 3 inches square but most of them will be closer to a 1 1/2" x 1" oval.

[Chuck Stone]

I don't do 'doming' per se, but have used similar epoxy resins. (Maybe Rodney will chime in)
I wouldn't use lacquer to seal, only because if 5 hours puts you behind, you'll hate lacquer.
It may dry to the touch in minutes, but it takes weeks to fully cure. And if it isn't finished
cross-linking, it can react with whatever else you put on it. (you might get the epoxy on
with no bubbles, only to find that the reaction is causing bubbles to form while it cures)

You can thin the epoxy a bit with acetone and put on a 'wash coat' that should dry faster,
as the acetone flashes off quickly. And even if the epoxy isn't cured, it won't react with
another coat. Might dry faster by half. (just a guess on that, though)

[Gary Hair]

Joe,
Why not use a UV curable epoxy? The stuff I use cures in about 20 minutes using Home Depot BLB tubes. The plus to faster curing is that you don't get as much dust and other contaminants settling on your parts when they cure in 20 minutes vs 5 hours. As for bubbles - yes, you will get them on wood. The cure is, as they said, to put a thin coat on first then finish the doming. Can't say for sure if your sanding sealer, clear lacquer or color will will react poorly with the epoxy, I would test it on some scrap to be sure.

Gary

[Joe Hillmann]

Is the uv cure epoxy a one part or two part epoxy?

[Gary Hair]

it's one part, no need for mixing since it cures with UV and not a chemical reaction. I got mine from epoxies.com, it's the dc7155. There are people who sell it online but they mark it up a ridiculous amount and it's cheaper to buy through the manufacturer!

[Rodne Gold]

I use very fast cure (1/2 an hour) 2 part urethanes and have vacuum chambers and a special dispensing robot...so my input here might not be that helpful.

However , I would suggest a 2 part epoxy which is much more forgiving than urethanes. The problem with any doming is 2 fold , 1..moisture (in the substrate and air) which causes bubbling and 2.. you need to mix EXACTLY...and gently , stirring vigorously just introduces air into the mixture..
Often its a good idea to use an oven or warmer drawer to dry the thing you are going to dome if it can absorb moisture...(like wood)
You can make a drying box for the domed stuff by inverting a carton with a 40w incandescent bulb inserted into it...works well to dry the air and to stop dust. Also diminishes bubbles in that they rise to the surface cos of the heat and pop , the heat also aids curing times.