Matt and Gloss Surfaces

Matt surface is fully mature and smooth in Egyptian Paste without
any gloss. An increase in alumina makes the surface more refractory creating a matt surface, or so I've read. I suppose conversely, this means that a decrease in alumina would create a gloss surface. Someday I'll monkey around with aluminum hydrate just to prove this to myself. For now, I use different recipes to achieve the gloss or matt.

It may just be the glaze layer is thinner causing the matt surface. It cetainly is not because it is underfired; experiments were run taking the firing a cone or two higher with no discernible different in the matt. This roses has a relatively thick layer that is quite smooth yet still matt. However, it is notice that the shinier Egyptian Paste layer of glaze is much thicker then that of the matt's.

Because I fire on my "bead islands" there does seem to be a gradient from top to bottom of the amount of glaze formed on the bead surface. In the image above, you can see the turquoise bead is nearly white where the glaze formed thinner. Where the glaze formed thicker of the surface is smoother.

The image to the right has two different recipes. The one in the foreground, the turquoise figure and beads is the recipe used in all my post up til now shows a Matt surface. The choir/pale figures in the background is the gloss surface recipe containing more sodium salts. All of my carefully sculpted details are obliterated.

Efflorescence in this gloss recipe was so great it was difficult to load it in the kiln without disturbing the surface. Sticking was another problem; a thick application of kiln wash was always necessary. The cleanup was labor-intensive, especially bead wire. The Matt Paste doesn't stick nearer so much.

On top of this I found I personally prefer the Matt surface , because it looks like Egyptian Paste from antiquity. Plus that, more surface details/textures are discernible with the matt Egyptian Paste; that is important to a sculptor.

The gloss surface has a crackle network that could be a useful design element if considered. Even though I'd abandon the glossy recipe for some time now, I must re-examine gloss recipes. Gloss does seems to be the one that comes up more often in questions/comments.

Bluetooth Beads!

Continuing with the excitement from the last kiln firing here's an image of something that went right. Turned out well both front and back. This is a rather simple bead to make just time consuming. An IBM Selectric typewriter element is used to give a sort of modern hieroglyphics; you can see the individual characters impressed on the beads if you look for them. Too bad there is not a Greek character ball in the studio texture toybox.

With a few spacer beads the Faience beads are strung on monofilament/fishing line temporarily, just to get an idea how they would look. They sure would be lovely strung with copper beads. We will call them “Bluetooth Beads”!

The bottom/backsides of these beads have no glaze on them, because there was no evaporation from that side, and therefore no salts could accumulate on the surface forming the glaze. That is the efflorescence in action that was mentioned in an earlier post. They were fired sitting flush against the kiln shelf. An aluminum hydrate shelf primer kept sticking to a minimum; sticking really wasn't a problem with this Egyptian paste recipe. The unglazed portion feels like a fine grain sandpaper or etched glass. The glaze side is a rather matte glaze smooth to the touch.

How can clay self-glaze? Efflorescence, that's how!

Every week I will introduce one little nuance on Egyptian paste. At this rate, we will acquire 52 characteristics of Egyptian paste in a year. Theoretically, anyone who can name 52 characteristics of Egyptian paste is somewhat of a master on the subject, no?
Moving on, efflorescence, is the term this week. I would describe it as a wicking of the salts in the Egyptian paste to the surface as it dries. The Egyptian paste has soluble salts in it; that is salts that are dissolved in water.
Here is an image of our miniature milking stool again; both before and after the firing to cone 06 (about 1000 C. degrees). It’s hard to see and photograph, but in the before picture there is a powder on the surface. The powder is like growing salt crystals. I’ll try to get a close-up photograph of the surface next time I fire a load of paste.