Low Fire Glaze Recipes

Easy Peasy Cone 04 Glaze Recipes

Experimenting with Cone 04 Glaze Recipes

• August 19, 2020 • Read Comments (28)

3ingredglaze
In today’s post, our own Holly Goring not only includes some versatile three-ingredient cone 04 glaze recipes, but she also gives simple straightforward explanations of the glaze chemistry behind them. If you have always wanted to experiment with your own glazes, but didn’t know where to start, this post is just the ticket.

And even though these are cone 04 glaze recipes, you might be inspired to experiment with the ratios of ingredients to come up with mid-range glaze recipes or high fire glaze recipes. – Jennifer Poellot Harnetty, editor.

I’m all about simple when it comes to glazes. First, my studio is small and I don’t want to sacrifice room for a lot of glaze materials. Second I don’t want spend time repeatedly testing glazes when I could be making work. While I enjoy the experimental side of making my own glazes, I want to eventually have consistent glazes that I know will work every time.

With those requirements in mind, I started by defining my basic needs: glossy, matte, and satin base glazes for a cone 04 clay body. They needed to be consistent and stable, and work well with both stain and oxide colorants. They also needed to work well over underglazes and slips.

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Glazes — Starting From Scratch

To determine what to start mixing I began with the fundamentals of what’s in a glaze. In its most basic form, a glaze is composed of a glass former, a flux, and a stabilizer. A flux is any ingredient used to help melt the glaze or to lower the melting point. A stabilizer is any ingredient used to stiffen the glaze and hold it onto the clay body, as well as to extend the melting range of a glaze in some cases. In ceramics this is typically alumina. The glass former is the main ingredient of a glaze and is supplied by silica. When combined in various proportions, these three basic ingredients will yield a wide variety of base glazes. The melting points and ratios of the three basic ingredients to each other determine the firing temperature.

Cone 04 Glaze Recipes—Ratios and Limits

Next I determined the ratios of each component. For a glossy glaze, the silica must be at least 8 to 10 times greater than the alumina. For a satin glaze, the silica is 5 to 8 times greater than the alumina. A glaze needs only 1 to 5 times more silica to alumina to yield a matte surface. The flux ratio balances the above two components. With a dozen or so possible sources of fluxes, many combinations are possible—this is where the real experimenting comes in. Fluxes are the main determiners of texture and how much the glaze will flow on the pot.

 

cone 04 glaze recipes

Knowing the chemistry and characteristics of your materials is important when deciding what to toss in the bucket. I’m generally not one to sit down and fine tune the science. However, I am willing to do a triaxial blend of three ingredients based on the information above.

Cone 04 Glaze Recipes — Choosing Materials

I started with EPK kaolin in each of my glazes as my stabilizer, as it supplies a good deal of alumina. It also provides the silica I need for the glass to melt. It’s fairly plastic and is considered the best kaolin for use in suspending glazes.

I added Gerstley borate as a flux in the glossy glaze. It’s a generous contributor of boron, which can decrease crazing and intensify colors. Gerstley borate is a bit controversial among ceramic artists—it has good application and melt properties but can cause glazes to settle over time.

cone 04 glaze recipes

For the flux in the matte glaze, I added whiting (calcium carbonate) which is known to work as a matting agent at low temperatures. It can also harden glazes and prevent pinholing.

I used dolomite for my satin glaze. Dolomite forms crystals upon cooling, and these crystals produce a smooth, silky surface.

I also added a Ferro frit to each glaze. Frits are premelted glazes ground into powder and some are formulated to melt at low-fire temperatures. Frit 3124 is an all purpose frit for developing strong colors. Frit 3195 is also high in boron and is very fluid. Frits add both glass formers and fluxes to the mix.

Finally, colorants were added in small amounts to the base glaze in the form of metal oxides or commercially-made stains. Oxides generally give you a transparent glaze while stains yield an opaque surface. I used a combination of both.

Results of Glaze Recipe Tests

After running a triaxial blend of my three ingredients and narrowing the results, I came upon three suitable recipes to test with colorants.

Glossy cone 04 glaze recipe: very clear and stable but exhibits a small amount of crazing and could benefit from the addition of more silica. It produces excellent color with oxides and stains while maintaining the white underglaze underneath.

cone 04 glaze recipes

Matte cone 04 glaze recipe: produces a wonderful clear matte. It works well over textured slips and also produces excellent color with oxides and stains. Apply slightly thicker than the average glaze for good coverage.

Satin cone 04 glaze recipe: makes a beautiful buttery, waxy surface. It is opaque and works best when applied thick. Both oxides and stains work well in the recipe.

**First published in 2014
Comments
    • Molly B.

      Hi, you can use either percent by weight or by volume, but it has to be used consistently throughout the recipe. If I’m making glazes with dry materials, I find it easiest to go by weight.

      • Leon N.

        Respectfully, it is a mistake to think that weight and volume are the same. Try weighing 100 grams of silica and 100 grams of magnesium carbonate to compare volume. Silica is much denser therefore smaller volume. Glazes are always expressed as percent by weight.

  • Deborah I.

    literally the best easiest and clearest explanation of glaze I’ve found in over 8 months of research, but then I have been looking for celadons up to high firing. but thank you for this. I have a small low firing gas kiln arriving tomorrow so I’m even more excited now!

    • Helen F.

      I am a relatively new potter using low fire clay and glaze. I am constantly told by high fire potters that my work will not be properly vitrified at low temperatures. My pieces look alright and function alright. I worry that They are right and I am wrong. I fire both bisque and glaze at 1000c. Does that make my products not suitable for use or ornament. Help

      • Colin M.

        Hi Helen, are you using earthenware? Ornaments it’s ok… Ideally, you should fire between 1000-1050c in bisque and glazes should be between 1060 – 1100c… all this does depend on what you are using your pieces for. If using earthenware clay you can burnish using a slip (for colour) and a bowl of a spoon to compress the clay, this will give you a sheen and is like samian wear or ancient greek/roman pottery but you can only fire up to about 800-850c as any higher will burn away your burnishing. All low fired ware can be used around the house but the other potters are correct in the fact that a low fired burnish ware can be brittle. As for firing to 1000c, most red or earthenware clays should hold up fine…juggling your ceramics isn’t recommended for any clays! Hope that helps!? Feel free to contact me if I can be of further help. Colin McGowan ceramicist UK cpm.ceramics@gmail.com

  • Geraldine G.

    as a new potter I found this information very interesting, glazes have always mystified me until now!

  • Donna K.

    That is quite interesting that Gerstley is considered to be an ingredient that hard pans. I have had the problem with Nepheline Syenite and some frits but never with Gerstley. In fact the problem I have with it, is it making a glaze gel. It then appear much too thick with little water. People will add water which causes too much shrinkage and the glaze cracks when drying. Deflocculent helps but it can still appear thicker than it is so the glaze must be weighed or a test tile dipped for checking.

  • Rasim B.

    hello. i saw you ceramic glazes recipes all of them are very good congrats.İ need low fair (1000 // 1050°C ) honey color; sea green and turquoise colors recipe.can you help me please.thank u very much.

  • Richard H.

    Pretty good article I do wish there is a little more details on the colorants for example I had a peice the I had used copper carbonate underneath the glaze as I did cobalt carbonate on an earlier peice and had disasterous results. Cone 04 I am not sure is hot enough to promote decomposition of either copper carbonate or cobalt carbonate into their respective oxides. As far as gerstley borate Ive never gotten the chance to utilize it.

  • Nancy W.

    I WANT TO BEGIN BUILDING A KNOWLEDGE OF COLOUR PRODUCING THINGS TO ADD TO A RAKU OR SAWDUST FIRING……..FALL LEAVES/COPPER FILINGS/ALUMINUMFOIL??? WOULD ANY OF THESE BE HELPFUL…..ARE THERE ANY ARTICLES IN YOUR ARCHIVES THAT MIGHT GET ME STARTED?

  • Jennifer A.

    The post is truncated on the right, but if you click on the “Print this Post” link at the top of the page, the print version is not truncated. Hope that provides temporary relief while the problem is sorted.

  • S B.

    I am also seeing the right side truncated, in Windows 8 / IE 11. If I set View > Text size > Smallest, it reduces but does not eliminate the truncation.

  • Diana S.

    I am having the same problem as Sophie. The right side is cut off. The post automatically opens in Mozilla Firefox (on my computer) and I don’t know any other way to open it. Could you post the recipe for the satin base, please? Not seeing that is the main problem. Thanks.
    Diana

  • Judy W.

    Gerstley Borate is available from Laguna Clay Co. It is almost identical to the original product.

  • Jharnetty@ceramics.org H.

    Sophie – This post is displaying fine in my browser (Chrome). What browser are you using so we can investigate? – Jennifer Harnetty, editor.

  • susan b.

    So where do you currently get gerstley borate? I had to switch to gillespie borate when gerstley became unavailable here. I’d love to find a supplier of the old stuff. Do they work identically in this glaze?

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