All Glossary

Dipping Glaze

In traditional ceramics and pottery dipping glazes can be of two main types: For single layer and for application of other layers overtop. Understanding the difference is important.

Key phrases linking here: dipping glazes, dipping glaze, dip-glazed - Learn more

Details

Dipping (or pouring and draining) is the preferred method for single-layer application of glazes on bisque-fired pottery, it is fast and coverage can be very even. When the slurry has the right thixotropic behaviour drying time can be measured in seconds! Glazes for dipping usually contain little or no CMC gum, suspending and hardening happen solely because of clay(s) in the recipe. 15-25% raw kaolin, ball clay or Gerstley Borate are typical in glazes having good working properties (a small addition of bentonite can be used in recipes having inadequate clay). People using dipping glazes tend to weigh out and mix their own recipes. Dipping glazes are available commercially but they are often just brushing glazes with no Veegum (they still drip-drip and take a long time to dry). But they do require CMC gum to harden because of the high percentage of frit. Their working properties are so poor in comparison to a thixotropic slurry that inexperienced potters or hobbyists, for example, can be soured on the whole idea of dipping!

For multi-layering, that is, applying other layers over a dipping glaze (with no firings done between), a base-coat dipping glaze is needed, one that contains a binder to fix it well to the body and harden it on drying. Binders are much more effective if the glaze has plenty of super-fine particles for them to bind with (thus bentonite additions are common in glazes containing CMC gum). These glazes dry slower, go on thinner, and drip a lot during draining.

On this website, most of the articles and reference material assumes the making of single-layer dipping glazes (unless otherwise mentioned). We promote understanding the relationships between recipes (of materials) and their oxide chemistry with what happens in the kiln. And the concept of recipe limits. Weekend warrior type potters are typically more interested in buying commercial bottled and gummed products and exploring all the colors and interactions of multilayering with them. Industry also has minimal interest in this type of glaze, not only because their formulations contain lots of frit, but because their machines and process also demand the use organic and inorganic additives.

Pre-Mixed Powdered Dipping Glazes

These are made by various companies. They come as a plastic pail with a measured amount (e.g. 10 lb) of premixed powder to which the user adds water (according to instructions about specific gravity, mixing). Potters Choice dry glazes are an example. The company is in a delicate situation selling these and the products are not readily visible on their website. The four pages of instructions (link below), the time required to mix, the complexity of the process and the equipment needed would be intimidating for users of brushing glazes. And it would require much more technical support. The process involves adding some of the water, letting it sit for 20 minutes and then mixing for 30, sieving, letting it sit overnight, mixing again, dealing with possible hard panning (and adding their Suspendaid product if needed), mixing again, doing cycles of checking specific gravity (targeting 1.39-1.41) and adding small amounts of water until the target specific gravity is reached, doing 5-second dipping tests to verify it is going on the right thickness and finally firing the tests. Users tackling all of this might well decide they could just as well add one more step of weighing out the powders using their own recipes. This method of mixing differs from that described above, they are using much more water and thus are not achieving a thixotropic slurry (that only needs 1-2 seconds of dip time). They put the emphasis on a consistent dipping time, thus targetting a slurry rheology to achieve that. They also do not recommend glaze layering, warning customers used to brushing glazes that this will not likely work (for the same reasons as noted here). Strangely, they do not provide instructions to mix as a first-coat dipping glaze. If you try mixing one of these as a thixotropic slurry, please let us know how it worked and at what specific gravity. If you had to add a cup of Suspendaid to prevent hard panning, how did that not push the specific gravity too low?

Related Information

Commercial brushing glaze on a non-gummed dipping glaze: Crawling

Non-gummed dipping glazes go on evenly and dry quickly on bisque ware (if properly gelled). But they only work well as a single layer. If you try to paint commercial gummed brushing glazes over them the latter will compromise their bond with the body, cracks will develop during drying and bare patches like this will result during firing. For multi-layering the base dipping glaze must be gummed (e.g. 1% CMC gum). It will go on thinner, drip longer and dry much slower, but that is the price to pay if you want to layer over it.

CMC Gum is magic for multi-layering, even for raw Alberta Slip

The glaze on the left is 85% of a calcine:raw Alberta Slip mix (40:60). It was on too thick so it cracked on drying (even if not too thick, if others are layered over it everything will flake off). The center piece has the same recipe but uses 85% pure raw Alberta Slip, yet it sports no cracks. It should be cracked much worse than #1. How is this possible? 1% added CMC Gum (via a gum solution) was added! This is magic, but there is more. It is double-layered! Plus very thick strokes of a commercial brushing glaze have been applied over that. Yet no cracks. CMC is the secret of dipping-glazes for multi-layering. The downside: More patience during dipping, they drip a lot and take much longer to dry.

Better to mix your own cover glazes for production?

Yes. In this case the entire outside and inside of the mug need an evenly applied coat of glaze. For hobby this makes sense. But in production cover brushing makes less sense. The right pail has 2 gallons of G2934Y base with 10% Cerdec yellow stain: $135. Cost of brushing jars with the same amount: $600+! And each jar logs 10-15 minutes painting time plus waiting between coats. The one in the pail is a true dipping glaze (unlike many commercial ones that dry slowly and drip-drip-drip). This one dries immediately after dipping in a perfectly even layer (if mixed according to our instructions). And a bonus: This pail can be converted to brushing or base-layering versions using CMC gum.

Can you brush a dipping glaze on to leather hard ware? No.

The body needs to shrink as it dries. Typical glazes have low clay content and shrink very little. So as the body shrinks underneath the glaze just flakes off. Brushing glazes contain significant amounts of gum, that gum bonds them securely to bisque ware, but not to unfired ware. As you can see here. the glaze bond with the body could not withstand the differential during drying.

Commercial glazes on decorative surfaces, your own on food surfaces

These cone 6 porcelain mugs are hybrid. Three coats of a commercial glaze painted on the outside (Amaco PC-30) and my own liner glaze, G2926B, poured in and out on the inside. When commercial glazes (made by one company) fit a stoneware or porcelain (made by another company) it is by accident, neither company designed for the other! For inside food surfaces make or mix a liner glaze already proven to fit your clay body, one that sanity-checks well (as a dipping glaze or a brushing glaze). In your own recipes you can use quality materials that you know deliver no toxic compounds to the glass and that are proportioned to deliver a balanced chemistry. Read and watch our liner glazing step-by-step and liner glazing video for details on how to make glazes meet at the rim like this.

Think the idea of mixing your own glazes is dead? Nope!

These are two pallets (of three) that went on a semi-trailer load to a Plainsman Clays store in Edmonton this week. They are packed with hundreds of bags of powders used to mix glazes. More and more orders for raw ceramic materials are coming in all the time. Maybe you are using lots of bottled glazes but for a cover or a liner glaze it is better to mix your own. And cheaper! And there are lots of recipes and premixed powders here to do it. One of the big advantages is that when you dip ware into a properly mixed slurry it goes on perfectly even, does not run and dries on the bisque in seconds. No bottled glaze can do that.

I have 161 grams of stain. I need to mix it into how much clear glaze slurry?

Stain powders are expensive. I want to make as much glaze as I can from every gram of this red stain I have at hand. I have weighed a teaspoon of my clear glaze liquid slurry (recipe G2926B). I dried it out under a heat lamp and weighed it again (top left). I have filled those two weights, 8.9 and 4.74, into a spreadsheet I made. It calculates the proportions of water and powder in the glaze slurry. I have filled in "10" for the percent of stain needed. It is telling me I need to mix the stain into 3040 grams of the liquid glaze. That gives me about 5 pints of glorious bright-red dipping glaze. The dipping process enables me to apply it so much more evenly than I can do by paint-on methods (provided that I have the right specific gravity and thixotropy). And, I got this much glaze for about $50 worth of dry materials (vs. $20 for a pint of paint-on glaze).

Inbound Photo Links

Learn to mix any of your glazes for these three application methods

The glaze cost on this mug is three times the cost of the clay!

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