How I Sign My Work

Signing with Ceramic “Ink”

I sign each piece with a homemade ceramic “ink” and a calligraphy pen. The ink is made from cobalt oxide, water, and a small amount of CMC gum solution. The CMC is important. It helps keep the cobalt evenly dispersed so it doesn’t just settle to the bottom. Getting the ink consistency right takes a little trial and error. If the ink is too thick, it won’t flow out of the pen. If it is too thin, it make drop out of the pen causing drops on the piece.

Before signing a finished piece, I practice a few times on scrap bisque. Once the ink is mixed and ready, I dip the pen and sign. The tricky part is that there’s no room for mistakes — cobalt stains the clay permanently, and you really can’t wipe it away. Any “slip-up” will still show up as a ghost image after glaze firing. So I always do a few tests before committing to a piece.

Waxing and Glazing

After signing, I apply wax resist to the base of the piece. I start by gently dabbing the wax over the signature with a brush. I don’t drag the brush as this would smear the ink. That first touch of wax helps seal in the ink, and after that, I can brush over it again to cover the rest of the base.

In case you are not a ceramicist, the reason wax is applied to the bottom of ceramics is to resist glaze adhearing to that area. There can’t be any glaze on the part of the piece that touches the kiln shelf. Glaze becomes molten glass in the kiln, so if it were on the bottom, the piece would fuse to the shelf as it cools.

For wax, I use Forbes water-based wax from Highwater Clay. It’s a great wax that can be thinned with water, which makes it brush smoothly and last longer. Sadly, Highwater’s facility was destroyed in Hurricane Helen, and I’m not sure if this wax will become available again. Fortunately, I have a gallon jug that should last me quite a while.

Once the base is waxed, the piece is ready for glazing and then on to the glaze firing.