I’m sure there are many of you who are now looking at making “proper” signs and the like because of Easel Pro, but you’re dreading how to actually get colour in the signs so the letters stand out. Do you just flood it then sand it back? Meticulously paint each letter with a tiny brush? Paint masks are here to help!
Inventables sell Avery paint mask (SF 100 if you’re shopping elsewhere), I’m using a similar product from Aslan called S79 (though some of my experiments were with 85G).
The long-story-short is paint masks applied before the milling process allow you to easily use spray paints or brushed on paints (more on that later) without ruining the surface and requiring a lot of clean up later if you do the adequate prepwork.
Now, I’m not an expert, but I’ve been experimenting and this might help others.
Paint masks typically contain a reasonable - but not double-sided-tape level - adhesive. As such, they stick really well to smooth surfaces, but less well to porous surfaces.
Sand your sign blank to at least 180grit, 220/240grit is a bit better
Make sure you dust/vacuum up any dust afterwards too, thats just going to inhibit adhesion
Apply some sort of sealer over top
This doesn’t have to be your final top coat, but it can be. If you’re unsure of what to go for here, try dewaxed blonde shellac. It won’t impart much of a colour to the wood, and being dewaxed you can stick just about any finish over the top. I’d probably advise against BLO or tung oil here as they don’t really seal the surface that well.
If you’re using shellac, a 1.5-2lb cut is enough, do two coats, sand with 220/240g after the second coat.
Applying the mask
(S79 applied to a “blank” of pine plywood)
Cut the vinyl sheet to the size of your blank, then peel back a little bit of the backer, and using a scraper or roller, slowly pushing it onto the surface. If you’ve ever applied contact to a book, its exactly the same process. You want to have a smooth, bubble free layer. Apply a decent amount of pressure, rolling/scraping over after you are done - you want that sucka to stick.
I’m currently using a ink brayer - this speedball brayer to be exact - as its what I’ve got on hand. I’ll likely be picking up Fastcaps’ Speed Roller as I use the brayer for wood glue ups, and the steel rollers of the fastcap product would be better for edge banding.
Should I wait?
If you look at the TDS of many paint mask products, they’ll list the immediate tack as well as the tack after 24hr or even 7 days. Due to unforeseen circumstances, when I was using the S79 I waited 24 hours, but the 85G I carved immediately. If you’re having issues with a proper paint mask, waiting a day to carve after applying may help you.
Make sure you’re also applying the mask within the appropriate temperature range!
There are a few important things to pay attention to:
- Dust collection - the bristles on most dust boots will likely pull the mask off - raise it up above the surface so its not touching. You won’t get as good dust collection, but it should still trap the dust. I had no issues when I raised it ~5mm above the surface, and had the vacuum on
- Bit selection. “Straight bits”, such as V-bits are fine. Downcut spiral bits are also fine (and if you’re doing a roughing/clearing pass, I highly recommend downcut bits so you don’t have to sand afterwards anyway), but avoid upcut bits. They’ll likely pull the mask away.
- Really critical shallow details? Make sure to factor in the thickness of whatever mask you’re using when you’re zeroing. The Avery and Aslan stuff is very thin, but some people use contact paper which can be thicker
Super tiny/crisp detail works out just fine if you’ve adequately applied your mask. The crown in the Gondor emblem measures about 12mm across.
Spray paints or acrylics applied with a foam brush to dab on work just fine. You could probably get away with a soft paint brush too,but be careful not to lift the edges with the brush. I think airbrushing could look pretty fantastic too.
Paint masks are designed to be solvent resisitive, so you shouldn’t have any issues with it melting on you.
Once its dry, peel it off. Wait until its dry though, you don’t want to accidentally mar your surface if the mask flips and falls on the workpiece!
(Jacky Dragon, on rubber wood)
In this example, the mask lifted during milling
The bristles were what ultimately did it in, but in this example I didn’t adequately prep the surface.
This is going to be a little bit more variable, as it depends on the paint, substrate, etc.
I don’t have an example of this on hand, however, sometimes paint will still bleed a little under the mask. It’s not so much under the mask, but along the grain. This is an issue with the capillary properties of wood. It will be more prominent in water based paints than oil/solvent based.
Once you’re done milling, before you can apply shellac into the carved area. It won’t hurt the paint mask so you can be very generous with it. This should seal up the grain, so the grain can’t drink the paint.