Dear Fernando,

I would be very careful to put the limestone into the kiln. If any water is inside the stone, it could explode. Beside this, the stone can become decomposed by the heat.

Under the name Mica hides a lot of different minerals. Some names are Muscovit, Phlogopit, Celadonit and many others. So you can not only one chemical formula name.

Mica-sheets you can buy by Thompson enamel. But in a lot of electrical devices as toaster, flat iron or other, Mica are used as an isolation. You can use this sheets too.

Instead of Mica-sheet you also can use as underlay for pliqué a jour, thin glass fiber mats. This glass fiber mats you can in model-making stores buy, which model assembly sets of ships, airplanes etc. sell. Buy a thin one! In the first use the glass fibre matts smoke a bit, but that is no problem.

You also can use as an underlay thin copper-foil.

Procedure copperfoil: Put the clean and smooth foil onto a unglaced ceramic tile or a flat stainless steel sheet. Apply the work piece onto the copperfoil. Fill the cells wet or dry with the enamel. If wet, dry before firing. After firing you can the foil grind away. If you also on the backside high gloss need, put the workpiece topside down so on a firing rack, that the enamel don't touch thr rack. Fire careful, control the firing and remove the WP directly, if the enamel surface begin to gloss. Otherwise the enamel plunge down.

Procedure Glass fiber mat: Put the mat onto a flat unglazed ceramic tile or onto a stainless steel sheet. Moisten the foil a bit if you want to fill the cells with wet enamels. Lay on the workpiece, top side up. Fill the cells with enamel. If nescessary, dry the workpiece and the mat. Fire. The next steps are the same as the procedure with the copper foil.

Advantage of the glass fiber matt: the mat is very easy to grind away. Make the grinding under water, otherwise little pieces of glass fibre whir through the air. And this will not exhilarate the lung.

Edmund 

   Hi Edmund, thanks again for your post, it's very clear and I will try it as soon as I get the mica sheet or the glass fiber mat. I have seen they sell here mica sheets for microwaves too, maybe they are the same kind of sheet that are inside the toasters you said. I will show here the result of the work.

   About mounting the perforated an patinated plate on the polished lime stone, I was talking about leaving it like that as a final work, not putting the stone inside the kiln, but now I am leaving that idea and will try this technique.

   Many thanks.

   Fernando

Hallo Fernando,

here a pictur of the glass fiber matt and on top a Mica-sheet. Both are about 1 mm thick.

Edmund

   Thanks Edmund, I got a mica sheet, and I'm trying it this weekend. One more question: since I am going to fill the cells with orange transparent enamel, should I put before, a base transparent enamel (some people call it flux) and fire it, and after this then put the orange an fire it again (just the way it has to be done when you have a copper background), or just to fill the cells directly with the orange transparent enamel and fire it ?

   Fernando

Hallo Fernando,

A flux base on copper or silver is used only to avoid direct contact of colored enamels with the metal. Come some transparent colors in direct contact with the metal, caused chemical reactions which can change the color dramatically.
If you work on mica or glass fiber mats, an underlay of flux is not nescessary.

Edmund

   Hi again and thanks for the last post. After four tries failing to get the cells filled (cause the copper plate bended with the heat and left space between it and the mica sheet) I got  the enamel attached to the borders right, but all the tries even the last one I got the enamel with a horrible bubbles and colour. When I put the plate inside the kiln around 835 Cº it started bursting with a granulated plaster texture and making those bubbles. It seems it reacts in a different way than when I  do it with the copper and flux background. To fill the cells I make a paste with the enamel, a few drops of water and gum arabic, then I fill the cells with a palette, pressing it and l dry it. I have done the same way with champleve even with the enamel more wet and with brush and it worked pretty good. 

In fact the second try I didn't use any liquid, just only the enamel powder and I got the same bad reaction. I am working with transparent enamel directly, without flux, like you told me here.

The enamel colour in this pic was supposed to be transparent brown.

 Any suggestion???

 Thanks in advance

  Fernando

What really happened I can not say. Normally, the enamel paint on mica plates not changed. The buckling of the plate you can minimize, if you  it onto a flat, heat resistant surface, for example, an unglazed ceramic plate, puts. Press the copper sheet down during the firing.

   Hi Edmund, nothing wrong with the enamel nor the mica sheet, I was not doing the firing well. I will show the result soon here when I get it.

Fernando

Hallo Fernando,

I had suspected. But from an image, it is difficult to judge where the fault lies. The end result is very good.

Edmund

   Hi everybody, since I went too far etching this plate and got some holes on it, firstly I decided to perforate the plate, patinate it and  put it on a polished limestone. But since I have read about the "plique á jour" technique, I am wondering if  it would be possible to get it done on this plate. I have read that it is done with a "mica" sheet under the plate when you fire it. The question is: if it was possible, what kind of mica sheet do you think  would I need? and where could I get it?

The plate measures are 16X11 cm (6'2X4'3 inches).

    Please, forget about the firescale in the pic, I will remove it and clean the plate, before I do anything.

    Thanks in advance.

    Fernando