Pottery and Ceramics Glaze
Crystalline Glazes Are Fun
Every time I put a crystalline glazed piece in the kiln to be fired, I can't wait to see what I'm going to get when I open the kiln.
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You can buy these glazes in any pottery or ceramic shop.
Frit Formulas Commonly Used
Ferro FritSilica 69.8%
Sodium oxide 15.3%
Calcium oxide 6.3%
Aluminum oxide 3.7%
Boron oxide 2.6%
Potassium oxide 2.3%
Ferro FritCalcined zinc oxide 23%
Calcined china clay 3%
Titanium oxide 4%
High Alkaline Frit
Zinc oxide 24%
China clay 40%
Titanium oxide 8%
Oxides of copper, cobalt and manganese are added totaling a maximum of 8%.
Each glaze component has a particular role but these are not single elements and their contributions overlap. The frit is designed to make the glaze melt quickly at top temperature. This presents a fully molten mix which is immediately ready for the new bonding to be formed. The rapid firing up to and down from the top temperature stops the formation of a body glaze layer which stops the forming of large crystals. Zinc oxide combines with flint and provides the zinc silicate for large crystals. The china clay gives stability and hardness to the final glaze. The flint is almost pure silica. It can be a different type from that provided by the frit for the main ingredient and supplies the structure for the crystals. Titanium oxide contributes to the start of crystals. It also brightens colors and helps with the movement of color in the glaze.
The oxides or carbonates which lose their carbon and excess oxygen with the addition of copper, cobalt and manganese, color the glaze body or crystals and sometimes both in specific ways, according to their strengths.
Crystals grow in the cooling glaze by the isolation of particular oxides from the surrounding glaze. Zinc silicate is most often the material of large crystals. In the hot liquid glaze body, the glaze minerals are loosened from their original combinations producing a fluid mixture of individual parts. In a normal glaze, as cooling begins, these parts link together to form irregular chains. This creates the changing substance, glass. For crystals to develop, the temperature is held for those periods when the parts start into more specifically organized chains. They establish bonds, which produce lattice structures, which are the framework of crystals.
The colors here are from ilmenite and cerium oxide which has properties similar to tin oxide.
This fringe edged crystal is approximately 1 1/2 inches across. It appears in a glaze with 1.5% vanadium oxide and 1.5% ilmenite in a Ferro Frit base glaze. This glaze shows how copper oxide can give a green stain to both crystal and glaze. The glaze has 3% copper oxide and 3% barium carbonate. The barium carbonate shifts the color towards turquoise.
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Have you ever come up with a good idea while working with your handmade pottery and thought that you would like to share it with others? You have? Well, why not send it to us and we will add it to the tips page for all to see.
Handmade pottery can be a very gratifying hobby that produces fun and satisfying results. For many people it's an enjoyable release that is created by working an inanimate mound of clay into a beautiful work of art that you made through your artistic abilities.
The best way of starting out is to take a few lessons from Youtube. You will probably waste quite a bit in materials when you first get started. Figuring out how to truly make handmade pottery correctly and shape into what you want it to be can be quite an ordeal. The different tools that a normal shop will have can be fun to try. You will soon see which ones you like to use the most and then when you are ready you will know which ones to buy.
With the help of the internet, you can now purchase most if not all of your ceramic and pottery tools and supplies online. We are located far from any well supplied dealers and yet working with reliable ceramic and pottery suppliers online has allowed us to recieve most of our orders within a timely manner.
When you get all set up, just enjoy the hobby and have fun at it. Some people get pretty serious and start selling their creations at craft fairs and small stores, but others just like to create items for themselves, relatives, and friends. Whichever kind of handmade pottery you desire to endeavor, enjoy the hobby and have fun doing it.
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