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I ran a test with 110 mica powders and found that most of them lost color at fusing temps. I did find a few winners though... I only tested capped and have been told the colors will act differently uncapped. I dread running this test again (uncapped this time). does anyone have any input for me on this? specifically uncapped mica keeping color?

What brand of mica? There are big differences between brands.

How high did you fire? Temperature is a factor.

How did you apply the mica? Different techniques yield different results.

Running lots of tests and taking good notes is instrumental to learning, especially since what works in one kiln may behave very differently in another.
Brad asked good questions, since mica quality is another variable.

Here's a test piece I did several year ago with mica from C&R Loo:

I tested some Pearlex, TKB Trading, Perfect Pearls. went to 1490 and used hairspray as my medium. if anyone is interested I could post the info for the"winners".

lorimendenhall wrote:I tested some Pearlex, TKB Trading, Perfect Pearls. went to 1490 and used hairspray as my medium. if anyone is interested I could post the info for the"winners".

I'm sure we'd all love to see the winners from your tests.

Two other brands to try -- Carefree Lusters from Thompson and any mica from Sepp Leaf -- these are both formulated for use at fusing temps, so will probably do better than a brand like PearlEx.

ok, I will post my results. I'll have to figure out how to post images... give me a minute... and thank you very much for the info about those other brands. I will try for sure.

the system is telling me the images I'm trying to attach are invalid...?

I tested about 110 mica powders - only a few kept their color at 1490.
I only tested capped, and have been told results will be different uncapped.

Here are my results:
Blue: I tested 16 blues and none stayed blue.
Purple: I tested 11 purples and none really stayed purple.
Pink: none stayed pink.
Green: I tested 17 greens. Pearlex Spring Green stayed about the same shade of green.
Red: none actually are true red, however very nice vibrant color with TKB Hot Step Mama, Pearlex Duo Red/Blue, and TKB Queen Kathryn.
Yellow: Pearlex Duo Green/Yellow fired goldish yellow.
Copper: TKB Passion Orange is a beautiful rich metallic orangey copper, TKB Lovely Leo is a lighter copper, TKB Bronze Mica is slightly tarnished understated but still rich copper, Pearlex Antique Copper is a nice tarnished penny color, Pearlex Super Copper is vibrant.
Gold: the best truest gold is Pearlex Aztec Gold. TKB Verdigris Gold is nice dark antique gold, Pearlex Interference Gold is a whitish sparkly gold, TKB Pisces starts out blue but strikes to a brilliant yellow gold, TKB Aztec Gold is a nice strong coppery gold.
Brown: TKB Swiss Chocolate is a nice rich dark brown.
White: the truest white is Pearlex Micro Pearl.
Silver: none fabulous, most sparkly brightest silver Pearlex Pearl White,Pearlex Macro Pearl a little darker but still shiny silver, Pearlex Antique Silver tarnished silver but appears to have burned away a little.
Miscellaneous:
TKB Sapphire strikes to a darkish but unsaturated lavender.
Pearlex True Blue strikes to a pale silvery lavender,
Flexi Glass Silver is really more of a metallic off-white.
Mona Lisa Bronze turned khaki with an even coating of bubbles.
TKB Patagonia is a pretty brownish plum.

lorimendenhall wrote:the system is telling me the images I'm trying to attach are invalid...?

Files must be jpg and under 256kb. If you don't have files that will work, email them to me an I'll convert and post for you.

Here are Lori's before and after images.

1490 is too hot for most mica. Try 1410 for 20 minutes. If you need the higher heat to get the glass to move the way you want, then you'll have to do separate firings. The best approach to applying mica is with an airbrush. Mix the mica with kleerfire and a bit of isopropyl alcohol. Build up a half dozen light coats and fire. Dry coats are better or you'll see splotches in the mica.

Tony

At 1410, mica will sink in to Bullseye glass and stick there. The micas that don't sink in will wipe off. At the same temperature on float glass, it will not sink in or stick. So, I add clear glass flux, or onglaze colors. The glass flux makes it stick and it works fine. (flux is finely ground clear glass. I have several in my collection. The one I usually use glosses around 1380ºF) The flux strategy will work on any glass.

I only use a few micas, silver, gold (a few shades) and 2 kinds of white, a mother of pearl (fine particles) and a supersparkle (large particles). They all work along with onglaze colors.

I'd love the full list of colors you tested.
I'm most interested in the TKB colors as that is what I have the most of. I'm curious about the small vs large micron sized whites.

I have a list of tkb mica colors that shows which colorants are used, I edited out anything that could possibly be hazardous (Cyanide salt based blues and greens). That still left me with a pretty extensive list.

Bert
What do you mean by onglaze colors?

haleybach wrote:Bert
What do you mean by onglaze colors?

The terms used to describe vitreous colors are extremely confusing. These materials are a mixture of clear glass (called flux) and metallic oxides. There are 3 different temperature ranges, based on the temperature it takes to soften and gloss the flux. At the bottom, they mature at 1050ºF. These colors are designed to be applied and fired on to glassware and bottles. The glass can take the heat without deforming. In the middle are a range of colors maturing around 1250ºF. These are often used in traditional stained glass painting. The colors in this grouping are often called enamels. Note that the word "enamel" is a useless term, as it describes so many diverse materials. The next range matures, and colors retain their vibrance, throughout the 1400ºF - 1500ºF. These colors were designed for use decorating china dinnerware. They are also quite useful on all sorts of glasses. I use the term onglaze colors which is what Ferro calls their Sunshine and Samba series onglaze colors. Potters also decorate with underglaze colors, which must be covered with a clear glaze. The onglaze colors have the glaze mixed in.

Thanks Bert, that clears some things up. I may start a new thread to ask more questions, I don't want to keep hijacking this thread.

When you use a flux with mica, what do you use?
The dry ferro type or something like "Spray A"?

Haley, I didn't test any TKB whites, only Pearlex. see my photo, 2nd row, last 3. Macro Pearl came out a medium sparkly silver, Micro Pearl came out white, and Pearl White came out a light silver.

haleybach wrote:Thanks Bert, that clears some things up. I may start a new thread to ask more questions, I don't want to keep hijacking this thread.

When you use a flux with mica, what do you use?
The dry ferro type or something like "Spray A"?

I believe either would do the trick. I am used to working with the dry powders, and I have a few in my collection. I take some powder (colored or clear), add some mica, these days I add some gum arabic to that, and then some propylene glycol and glycerine to complete my painting medium. If I am going to spray it, I mix it as a paste, put it in a jar, and add isopropyl alcohol, then shake. I would also leave out the glycerine, as it's job is to slow drying, and I want it to dry quickly when spraying.

Spraying is a way to get both a light coating or a very heavy coating. Brush painting has a much narrower range, somewhere in the middle.

There are all sorts of media that can work. A good one is Seven Up. Best if you let it go flat. The sugar is a burn off binder.

I have found that mixing micas in allows me to fire paint side down. I do have to dry it first. I can make a bowl in one firing this way, and the interior of the bowl is clear glass. The outer surface is made matte by the mica. You have to learn how much to use by eye, and trial and error. The float glass I use is stiff enough at 1400ºF, to keep a good shape in a slump mold.