Earlier this week I wrote about my latest marquetry practice. While I can certainly stand to practice many, many different aspects of marquetry there were a few specific areas that I was really interested in.
First, sawing with a “coarse” 32 tip blade. This is a control issue for me, and the results are in on that: the coarse blade is substantially faster and with more practice I think I’ll learn to control the “wandering willies”. The second goal was to practice sand shading, which is probably self-apparent. Sand shading is conceptually simple but the subtleties of how parts are shaded it an art. Finally, I wanted to do a marquetry design in the Boulle style where all of the layers in the packet were utilized.
Andre-Charles Boulle built some absolutely insanely ornate furniture in his day. He would have packets of wood, brass, pewter, bone and tortoiseshell that would be used in different combinations either on the same piece of furniture or to make a second piece of furniture the inverse of the first. For example, one application would have a tortoiseshell background with brass filigree and the other would show the reverse – brass background and tortoiseshell filigree. My approach is simplistic, a single rosebud design and four layers of veneer — two light and two dark. The rose is an element from a larger design I want to use on a real project.
First the sand shading. I looked at the drawing of the rose and marked where I thought the shading should go. For petals that were clearly under an adjacent petal that was clear enough. For petals that are made of several pieces with the intent of showing the piece curled at the edge it was more of a judgement call for me.
After seeing the result I’d probably make some different decisions in a few places, but that’s the point right? The actual process of sand shading is as exciting as you would imagine. The obvious part: stick the area to be shaded into the sand until it darkens to your liking. The less obvious part: sometimes it’s hard to shade the area you want. For example, a crescent moon shape where you want the inside of the curve shaded, but the tips not at all. You can mound the sand or scoop it up in a spoon to try to get it to the spot you want, but I need more practice still.
The other non-obvious part is that the heat from the sand makes the little jigsaw puzzle pieces turn into crunchy curly fries. Especially long narrow parts (think “flower parts”). What I’ve been doing is to sand shade a part, and if it curls I moisten it with a little water on my fingers. As the piece relaxes I gently (“crack”, “s#$%t”) flatten it on the parts tray. I hold it there for a minute, pressing it flat. Then I move on to sand shading the next piece. If the flattened piece is still behaving nicely after a few minutes I’ll assemble it into the temporary composition on shelf paper.
As long as the pieces are flat, have any bubbles in the paper facing I added scraped off, and bits of sand removed, the shelf paper makes a great temporary assembly process. It adds extra steps in the process over what we learned in class, but it’s a necessary crutch for me right now.
I had far fewer problems with the paper facing I laminated on bubbling up this time. Previously I got big bubbles in the paper on nearly every piece, like this:
The difference, I think, is two things. First, I was extra careful to use the least amount of glue I could. I probably had it slightly more diluted too. The process we used in class was to apply glue to the veneer, lay a piece of newsprint into the glue, cover it with another piece of paper and use a dry fingernail brush to rub the lamination together to force any air or excess glue out. I added another step which was to press the layers overnight between two cauls. That also helped counteract the natural curl from the lamination.
The sand shading process took me close to three hours. Crazy, right? About 160 pieces of charred wood. That included the shading, some piece sorting to figure out what-goes-where, and lots of wetting-and-flattening of potato chip parts. It also included several rounds of back-stretching and one particularly entertaining session of laying on the concrete floor looking for a missing part. I found it.
This view is the “glue face”, it will ultimately get glued to the substrate. So I went through the usual drill of putting blue tape on the glue face to hold all the pieces in place, then removed the shelf paper from the show face, and glued that down to the kraft-paper-covered pattern board.
Once that bit of indirection was accomplished I had the parts firmly attached to the kraft paper and the glue face showing again. It’s time for filling the saw kerf with “mastic”. I’m using diluted hot hide glue, fine sanding dust and a bit of powdered black tempera paint. Not tempura, that would be weird and I don’t the the panko would work as well as sanding dust for a filler.
I upgraded my “mastic tools” to be closer to what we used in class. The bowl is a silicon rubber bowl used in the dental industry for mixing mold compounds. It was cheap on eBay, although I had to buy a set of three. I guess I have backups. The putty knife I ground so it fit the bottom of the bowl, it works really well for mixing.
The mixing process is simple, although I need to work on quantity and proportions. Put a tiny bit of boiling water in the bowl, use the glue brush to swirl some hot hide glue into the water. Add a tiny bit of black paint and enough sanding dust to make a consistency like chocolate pudding. Mix well, then add more sawdust until you have something closer to joint compound. I used a bit too much black I think, and mixed waaaaay too much. Start with a teaspoon of water, ending up with maybe two teaspoons of liquid after swirling in the glue brush — maybe less. You don’t need a lot of mastic to fill the kerfs, and you don’t want to spend a lot of time sanding to produce the dust to make the mix.
Then, obviously I guess, use the spatula to force the mix into the kerfs, and scrape off any excess. I usually (*lightly*) block sand it after the mastic is completely dry to remove any lumps or ridges.
On with the show… Cut the kraft paper around the outside of the design to free it from the pattern board.
One of my next projects is to build a veneer press to make clamping these things simpler. The screws are ordered, I just need to get wood and decide how to build it.
Out of the press, the next step is to wet the kraft paper and scrape it off, exposing the design finally. It takes me about three rounds of wetting and scraping with a single edge razor to get a clean surface.
I finished this by brushing on a couple of coats of clear shellac, sanding lightly, and repeating. I’ll need to assemble my thoughts and learn to French Polish in the future. Good, something else to practice!
Here is the finished panel. I’m happy with the overall result, although I see several things wrong. I won’t belabor the mistakes, this was just for practice and learning.
What’s next? My first priority is to do some shop organization. I have a few tools that don’t have a place to be put away, so the horizontal surfaces in the shop are collecting things. I’ll probably set up another practice exercise to work on my sawing — something where the shape is critical. I want to start on a real project, using marquetry, in a couple of weeks. Just as soon as I build a storage cabinet for tools and a veneer press. I’m leaning toward a wall cabinet to store DVDs with a marquetry panel on the front. I haven’t been able to reconcile marquetry and Greene & Greene into a design so this cabinet will have a different aesthetic than my recent furniture projects.
One more cuppa, then I’m going to the lumberyard for plywood.