Turning Wood Into Stone

Yesterday, I got a great question on Instagram: why use putty? Why not just use gesso? The answer lies in the purpose of each substance: putty is used to fill in gaps while gesso is a primer. The effect we’re hoping for, on this inglenook, is limestone and that means getting rid of the–completely unavoidable–gaps between the trim we’ve just applied and the MDF we’ve applied it to. We could, potentially, get the same effect with gesso but we’d have to use many, many coats.

What I prefer to do is begin with putty on those areas that need it and then, after several rounds of sanding, apply gesso as a primer/base coat. Gesso, like pretty much everything else we’re using, works best when it’s applied in thin, even coats. Gloppy, thick coats might seem like they’re hiding a multitude of ills but really, they’re replacing one issue with another.

Here we are, ready to start. I’ve selected this piece, to begin with, for demonstration purposes as the need for putty here is fairly obvious. That mantel is a compound made from four different trims and, right there in the back, there’s a gap. Plus, the butt end of any wood, but especially a softer wood like basswood, is extremely porous. Putty will both fill in that gap, as well as seal off the grain for further sanding.

All of my sub-assemblies, ready to go. The ones without trim won’t need putty; I’ll put those aside until I’m ready to gesso everything. This, by the way, is a good time to make (another) pitch for keeping your workspace clean. This is my workspace ONLY; I don’t store anything here except those things I use all the time (like paint, brushes, etc). My wood, and other woodworking supplies, are in the garage with my table saw and so are my various trims, kits, and so forth. Storage-wise, here’s a plug for another company that really should sponsor me but doesn’t: ArtBin. I really like their Super Satchels, and accompanying cubes.

I really like AK Interactive putty. It comes in white and gray; I use gray, which is meant for finer applications. Here I am, applying it with a brush. Again, MANY THIN COATS! The last thing you want is to give yourself a mountain of dried goo that’s impossible to sand. Generally, I dip my brush into my water, before taking up a little putty. I try to work as quickly as I can, while still maintaining attention to detail; this stuff dries quickly!

MUA tricks are useful for art, too!

Once the putty is dry, before you sand, you can press a blade into the crevices between blocks of “stone” to shape them. Then, the next step is to–after making sure everything is REALLY dry–lightly sand over what you’ve done. At this point, you’ll probably notice a few areas where unwanted seams are still visible. You can touch those up, wait, and sand again. Do NOT leave any seams you don’t want, hoping for a quick fix with gesso.

This hearth was a doozy. I took this pic before I started sanding; note here how this seam is ragged and uneven, and could really benefit from that knife trick. For sanding, I used a combination of wet/dry sandpaper (sometimes wet, sometimes dry), nail files, and automotive sponges. Pretty much everything you need, sanding-wise, you can get at Sally Beauty Supply and Pep Boys.

The real litmus test, when it comes to sanding, is: is this smooth to the touch? Our eyes can deceive, as can our exhaustion. Personally, I have the most success when I break up these less…inspiring steps into chunks of an hour or so at a time. One trick I learned in grad school, which benefits me to this day is: work for 50 minutes, take a walk for ten. Our minds are active when our bodies are. I can spend all day painting, pretty much, with a few small breaks but after about two hours on something like this putty project I find myself wanting to rush. At that point, I take my son out for an apple cider donut or something.

Stay tuned, for gesso–and next steps! Going forward we’ll be doing first limestone, then brick, then tile. After which, we’ll start tackling the gilded, coffered ceiling. I promise you, none of this is as hard as it sounds!

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