Studio Tip: Working with Mica

September 07, 2015

Studio Tip: Working with Mica

Experimenting with Super
Spray and mica powders

I am always looking for ways to work with mica powders. I love the shimmer, but I often struggle with ways to use it in fused glass. Typically, when mica is sifted on top of the glass, only the very bottom layer of mica in contact with the glass will stick. A lot of your mica powder gets washed down the drain when the glass is cleaned. Several manufacturers have created products that capture or simulate the shimmer of mica, such as Unique Class Colors Accents paints, Glass Glo, and Glassline Metallic paints. These are all good products, but what if you already have a supply of mica powders?

In thinking about the problem of mica not sticking to glass, it occurred to me that the mica would be more likely to stick if the glass were "softer" during firing. And glass fusers know that a devitrification agent like Fuse Master's Super Spray does just that -- it allows the glass to soften more quickly than it would otherwise at the same temperature. This thought led to experimenting with Super Spray and mica powders. Following are the results of my experiments.

Mica dusted over the glass with
some areas coated with Super Spray

In this first piece, I brushed Super Spray over the glass in some areas, sprinkled mica powder over the entire surface while the Super Spray was still wet, and fired. The areas of glass that had the coating of Super Spray held on to the mica a lot better.

Mica and Super Spray "paint" applied
to the glass with a palette knife

In the next instance, I mixed the Super Spray and mica powder together, making a "paint" that I spread onto the glass with a palette knife (it was a little thick... just short of being a paste rather than paint). I really like the look of this swirled piece.

Encouraged by my results, I decided to work on a larger piece with color. Here is a piece of Spectrum's Fuser Reserve with both gold and copper mica powder mixed with Super Spray and brushed on:

Mica painted on the glass before firing

Mica after the firing

Close-up of the mica, which partially burned away

Oops! What happened here? As you can see, my original coat of the mica was a little too thin. On the darker glass, it "disappeared" except in places where the mica was thicker. (This piece will be sandblasted and re-fired for another day.) The gold mica also lightened up in color significantly.

Comparison:
Super Spray mixed with Sepp Leaf & Kaiser Mica powders

I have both Sepp Leaf and Kaiser mica powders. My first assumption with the Fusers Reserve piece above was that perhaps the Kaiser mica powders had burned off more readily than the Sepp Leaf (Sepp had been used in all my tests prior to this piece). Another test piece (at right), however, showed that both mica powders performed similarly (Sepp on the left and Kaiser on the right).

I think mixing mica powders with Super Spray has some possibilities, and it is something I will explore more in the future. In the meantime, as a point of comparison, here's a completed project that uses Unique Glass Colors Accents paint on the rim of an 8" bowl. Also, if you ever get the chance to take classes from Barry Kaiser of Kaiser Glass (and the Kaiser micas), he has some great techniques for making mica adhere to the glass.

I hope this information has sparked some ideas on how you can use mica powders in your work. Happy fusing! Dana