Finishing Wood for Engraving

Community Laser Talk
1

I have been making some plaques for laser engraving. I’m currently using juniper wood, and finishing it with Minwax Polycrylic before engraving. The finished wood is gorgeous (the woodgrain of juniper, especially heartwood, is beautiful).

My problem is that when I engrave, the finish around the engraving has a tendency to bubble up and create an uneven surface, especially in the darker areas of the engraving. Can anyone provide some input on how to minimize the problem? Options I’ve considered include using a different finish (like a water-based polyurethane), finishing after engraving, and doing multiple passes at a lower power. Any other thoughts?

2

The heat probably melts your surface treatment.
Possibly you need to change your workflow, use tape and treat the surface afterwards?

1 Like
3

I seal all of my work with either spray lacquer sealer or latex sanding sealer before engraving or cutting.

4

I use Minwax tung oil, either before or after engraving, doesn’t seem to matter. It’s quick and has a rich feel to it.

5

I was using tung oil in the past, but it’s darkening the wood more than I like. I’d do the burn prior to finishing with Polycrylic or polyurethane, but I end up having to deal with “smoke-stains” that soak into the wood surface even with air-assist. At this point I’m leaning toward a very light seal-coat, followed by the burn, then cleanup, and finally a coat (or more?) of the final finish.

6

When considering which finish to use before engraving, you need to consider not only the appearance but also whether toxic fumes will be produced.

In addition, a finish can also increase the inflammation

I treat my wood with walnut oil to which I add 10% beeswax, but only after engraving/cutting.

7

Indeed, that is a very important issue. That’s why I have the laser in an enclosure with a forced ventilation duct to the outside of the house. It’s also why I won’t even try to engrave or cut certain things… Vinyl, Polyurethane, and Nylon come to mind as examples of that. I’ve seen more than one laser machine absolutely destroyed by fumes from cutting vinyl sheet (HCl fumes are hard on most metals, and HCN is simply nasty and dangerous)