Mosaic hollow-form

This project was inspired by one of Philip Moulthrop’s hollow-forms, which I saw in an exhibition at the Atlanta Botanical Gardens.

The project begins with a simple hollow-form which will serve as the base for the mosaic work. This base can be any wood at all; it will be almost entirely carved away in the process. I made a base from a cut-off of a mahogany ballister, that was approximately 7″ diameter.

Base hollow-form; and some mountain laurel branch pieces.

I then attached the mountain laurel pieces around the outside of the base. At first I used epoxy mixed with coffee, but that took too long, and I switched to CA glue.

Base with mountain laurel pieces applied to exterior. You can see the chuck tenon at the bottom of the base.

Once all the mountain laurel pieces were in place around the outside of the base, I began to fill between the pieces, with a thick, coffee-epoxy mixture. The coffee served to make the epoxy black, and also to thicken it so it wouldn’t run after being applied with a putty knife. Then, after the epoxy cured, I put the hollow-form back on the lathe, and began to round the outside.

Starting to turn the mosaic hollow-form. Note that you can see the base hollow-form, just inside the top opening, under the mosaic layer. It will be turned away once the outside is finished.

Once the mosaic-layer outside was turned round, I turned away the base on the inside, so that none of the base remained, except on the bottom. The wall of the hollow-form was now nothing but mountain laurel branch pieces, held together by coffee-epoxy.

I am using a gooseneck lamp to illuminate the inside of the mosaic hollow-form, now that the base has been turned away. The lamp also helped identify locations where there were gaps due to incomplete coffee-epoxy fill, which I then had to re-work from the outside.

Once the outside was completed, including filling gaps, I put the hollow-form on my ‘Epoxinator’ (slow-rotator) for the application and curing of several coats of clear epoxy as a surface finish on the outside, and also on the inside.

Epoxy finish being slow-turned on the Epoxinator.

The hollow-form then had to go back on the lathe, using a vacuum chuck, to remove the tenon and clean up the bottom. Then, more epoxy to finish the bottom, and we’re done:


Robert started woodturning in 2015, after retiring from law practice and software development work. His woodworking shop, Black Rock Woodworks, is in Clayton, Georgia, where he resides on Lake Burton.