Stone Inlay - a tutorial for the "Birches" #3: Finishing the Piece

Hi, all, and thanks again for reading.

We left off with the piece having had its “first” grind. The idea at this stage is to get the stone almost, but not quite, flush with the wood. This reveals unfilled voids in the inlay that have to be filled. This is where the finer material, especially the powder, comes in. The trick is to fill in the gaps and voids with the powder, then carefully fix it in place with water-thin CA glue. I have found applicator tips to be a must-have for this. The standard tips that come with CA glue are not controllable, and you can end up with glue everywhere.

Another safety tip:
CA glue is a very chemically active substance. It bonds skin instantly. It will wreck your eyes. The fumes are dangerous. If you use a lot of it at once as you must in doing inlay, the curing process can suddenly get very hot; hot enough to burn skin. (Believe me I know!). Nitrile gloves are a must as is good eye protection.

So, please use extreme caution when using the large quantities of CA glue needed for this type of inlay. I use a respirator, and I use a fan to blow clean air across the work area, directed toward a large exhaust fan so the fumes are carried off. You will probably also need to use some curing accelerator from time to time. It really stinks and is very flammable and toxic. Just stay on your toes, use appropriate safety equipment, and go slow! This is not a process for children!

Now, the void filling process can take many steps of fill/sand/fill/sand. It will be up to you how perfect you want the surface to be. You can fill pinholes and depressions in the surface with a medium viscosity CA glue that stays in place. Once the holes are filled to satisfaction, progressively sand through at least 400 to get the inlay smooth and flush.

As you might imagine, you can really go through a lot of glue. Resist the urge to buy the mega bottles, though. I have had to throw out lots of glue that cured in the bottle before being used up.

In this case, I decided to leave the trunks “proud” of the surface rather than perfectly flush. It is very difficult to capture with a camera, but they really stand out. The trick was to sand the stone smooth without making it flush. All I can say is that it took awhile to carefully sand it without eating away too much wood at the edges.

Once I had the trunks, branches, and rim pretty much sanded smooth to 320 or 400 grit, it was time to inlay the leaves. At this point, I experimented with sprinkling some small chips to simulate the effect. I wasn’t sure I wanted leaves until I did this. I decided the leaves gave the piece more dimension and “pop.” I liked the mix of mostly malachite, with a few yellow leaves in sulfur.

Here you can see that the leaves are completely in powder carefully placed into the impressions and fixed with CA glue.

Here is a shot of the carbide down-spiral cutters and the hand-piece I use. Note that I added an air hose to the hand-piece to blow away the sawdust. This really helps during the inlay process, since the details are very small. The cutter I used for the leaves is the 1/32 size. tiny!

Now, the rest of the process is about finishing. You have to carefully sand the mineral inlay to at least 2000 grit before adding wood finish. This is quite laborious, but when you hit 600 to 800 grit, the minerals start to shine up and it gets pretty exciting. By the time you hit 2000, the stuff is like glass!

Once the sanding was done, I used a tung oil/varnish mixture (cut with naphtha). I use a high quality marine varnish with good UV inhibitors to protect the wood and 100% high quality tung oil. These pieces look best in fairly bright light, so the UV filter is important.

Don’t worry about getting varnish on the inlay. Between varnish applications, rub the surface with 0000 steel wool and allow the final coat to cure.

Now, the final steps! To get the really great finish these pieces need, I use the three-part Beall buffing system. The first compound (brown) will remove any varnish from the minerals. The white diamond compound will shine it up, and the final carnauba wax will make it breath-taking! Don’t skimp on the final sanding and finishing. The final hours are where the real payoff lies!

Well, that’s it! I know there are a lot of tips and techniques I have developed that I forgot to mention. So, feel free to send a message or comment on the post if you have questions.

Below is a shot of the next piece coming along. It is a buckeye burl vase with a lapis lazuli inlay.

I have found stone inlay can add incredible depth, color and texture to my artwork. Give it a try!

Blessings,
John

-- patience is a virtue ... in woodworking, cooking, and life in general