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Are all mica powders the same in regard to their temperature limits? I picked up some mica powders from a pigment company and they seem to be burning out at lower temps than I want. Any information would be appreciated.

Terry Gallentine wrote:Are all mica powders the same in regard to their temperature limits? I picked up some mica powders from a pigment company and they seem to be burning out at lower temps than I want. Any information would be appreciated.

No, they are not all the same. Some brands are made to withstand higher temperatures.

We use and sell micas from Sepp Leaf, which can be fired to 1600F or a bit higher. http://www.warmglass.org/othersupplies/mica

No. Some of the "micas" are not colorfast.

Look at Thompson Enamel Carefree Lusters. A number of us have been quite successful using them over the years.
https://thompsonenamel.com/advanced_sea ... n2&x=0&y=0

Also, do a search here for Pearl-ex powders. I've had good luck with some of the stronger colors.

CR Loo carrys micas that are decent performers as well.
http://130.94.190.116/Products/Fusing__ ... owder.html

But like anything, test them before you commit to making an important piece with them.

Tony

Thank you for this timely post! I was just putting together a series of questions on this topic and would like to ask a couple that haven't been answered:

At what temperature do CR Loo micas become one with the glass? 1380-1450℉? I have had some for about twenty plus years but never used them. The CR Loo site seems to refer to glass blowing applications only. There is nothing on the packets.

I also have Thompson Carefree Lusters (1100-1400℉) and a jar of TE Essence with no explanation on the label. It, and the Lustres and some Thompson enamels for Float Glass and Steel, came with a barely used kiln I bought. It the TE Essence the medium for mixing with the enamels? It's not mentioned on the Thompson site.

Are the terms 'Luster' and 'Mica' interchangeable?

Thank you for any clarification. Jen

Buttercup wrote:Are the terms 'Luster' and 'Mica' interchangeable?

Thompson uses the term "luster" to refer to their micas. As far as I know, no one else uses that term to mean mica.

The only issue I have with the Thompson is that they carry a health warning, while the Sepp Leaf people say there are no health concerns with their product. Thompson does come in some colors that Sepp Leaf doesn't, and PearlEx has a lot of colors, some of which fire off in the kiln and some of which are steadfast.

Thanks, Brad. As mentioned, they came with a kiln so I didn't select them. I'll use them carefully when I do.

Any idea what the TE Essence might be? Jen

Jen,
I think Essence is the solvent they use for their liquid gold (as in real gold salts that fire to pure gold.)
Warren

Thompson uses terms that confuse everybody. They are the only company that refers to their micas as lusters. Metallic Lustres are a completely different material. Metallic lustres do have a medium referred to as essence. I believe it is a very pure form of turpentine. I have no clue what Thompson may call essence

Back in the day, there was one manufacturer of micas, that made a wide variety of colors. The temperature stability of those colors does vary. There were a wide array of companies that bought, used, and resold these micas in various products. Pearlex, Jacquard, Thompson, Sepp Leaf, etc were all using the same stuff. Prices vary widely. The original manufacturer was Engelhard. Engelhard was sold to BASF. Then the Chinese got in the game. I have no clue who is using mica from BASF and who is using Chinese product this decade. The same micas are used in a wide variety of materials like plastic, paint, makeup etc. Look at the finish on your car. Chances are there is mica used in either the paint or the overcoat. We totally lucked out that this stuff is temperature stable in the glass fusing range.

The time and temperature are critical as over firing results in Micas that are less intense. Try some test runs, but I use 1405 for 15 minutes.

Tony

Question: are these actual mineral micas or manufactured. I used to actually go get mica out of the ground, crush it and then use it in some of my blown wares. BTW: there's a lot of it near Penland, I have to admit it was a real mess as it stuck to all the tools, blocks and everything else. After the 1st experience I dedicated tools only for the use of mica pieces. If these are the natural mineral, how do they go about doing the colorations in these as I've never seen a huge color palette in natural mica.

Tom Fuhrman wrote:Question: are these actual mineral micas or manufactured. I used to actually go get mica out of the ground, crush it and then use it in some of my blown wares. BTW: there's a lot of it near Penland, I have to admit it was a real mess as it stuck to all the tools, blocks and everything else. After the 1st experience I dedicated tools only for the use of mica pieces. If these are the natural mineral, how do they go about doing the colorations in these as I've never seen a huge color palette in natural mica.

The actual mineral micas come in about 25 different colors, mostly golds, bronzes, etc. Some companies, notably PearlEx, add coloring agents to make them purple, pink, blue, etc. Some of those added agents can withstand fusing temps, some can't.

When I was younger you could walk along the Appalachian trail and pick up mica. No longer, it's all gone, as is I suspect the stuff near Penland. The mica mines in the NC and VA are pretty much played out as well, most of the mica we use nowadays comes from India.

As an alternative you can use china decorating products
http://www.thegoodstuff.com/jm01.html

Don Burt wrote:As an alternative you can use china decorating products
http://www.thegoodstuff.com/jm01.html

I noticed they recommend cone 014, which is around 1540F and caution that firing to a lower temp may lead to scratching. Have you tried these at lower temps?

Brad Walker wrote:

Don Burt wrote:As an alternative you can use china decorating products
http://www.thegoodstuff.com/jm01.html

I noticed they recommend cone 014, which is around 1540F and caution that firing to a lower temp may lead to scratching. Have you tried these at lower temps?

I have not used those. I've used her 'glass paint' equivalents. (in a different section of her site). I really like the way they look. But the metallic glass paints require somewhere around 1325F in my kilns (with no hold) to make it so they're smooth and you can't rub off any of the stuff. I noted this the other day on here but I'll repeat: Kathy lists the metallic glass paint as requiring: 'Fire to Cone .022, 630 C, 1165 F', I don't know whether the glass paints are simply the same porcelain paint with some low-fire flux added, or whether they're a completely different base frit. But cone .022 (measured by legitimate cones in my kilns) doesn't cut it for the metallics, on flat glass on a kiln shelf. It takes more heat work. Kathy paints goblets and stuff. That may be the difference in heat work, having the actual painted part of the piece up and away from the shelf, in one of her porcelain kilns.

Tom, the micas we are talking about are manufactured from the mineral. I believe they use titanium and some hitech process to get them to turn colors. They are carefully graded to particular particle sizes.

Thank you all so much for the additional information. For some reason I didn't get an email notification that there were new posts on this topic and just found them when I wanted to review the info I'd read so far.

I also have just reread Avery Anderson's contribution to Rick LaLonde's Book 11, Richard Lalonde and Friends, with a greater understanding thanks to all the info gleaned here and in PM's.

Now to experiment. Thanks to all again. Jen

To give credit where credit is due, I learned almost everything I know about micas from Avery Anderson.

Tony

If anyone wants a copy of my mica test results pls email me at lorimendenhall @ cox.net

Warren Weiss wrote:Jen,
I think Essence is the solvent they use for their liquid gold (as in real gold salts that fire to pure gold.)
Warren

Thanks, Warren. There was no liquid gold in the paint and mica (lustre) collection I acquired with the kiln, however I do have some Liquid Bright Gold that I've never used. Laura Turner gave it to me, along with a pen, in exchange for a painted and fired piece some time last century. It may well have solidified by now. I did ask some time ago what to use if it does prove to have dried up but can't find the answer in my notes. It's worth trying the Essence. Thanks, Jen