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Here is my setup to make brushing glazes and underglazes by-the-jar

Although I promote DIY dipping glazes, you can also make DIY brushing glazes. Let's make a low SG version of G2934BL. Weigh out a 340g batch of dipping glaze powder. Include 5g Veegum (to gel the slurry to enable more than normal water) and 5g CMC gum (to slow drying and impart brushing properties). Measure 440g of water initially (adjusting later if needed). Shake-mix all the powder in a plastic bag. Pour it into the water, which is blender mixing on low speed, and finish with 20 seconds on high speed. This just fills a 500ml jar. In subsequent batches, I adjust the Veegum for more or less gel, the CMC for slower or faster drying and the water amount for thicker or thinner painted layers. Later I also assess whether the CMC gum is being degraded by microbial attack - often evident if the slurry thins and loses its gel. Dipping glaze recipes can and do respond differently to the gums. Those having little clay content work well (e.g. reactive and crystalline glazes). If bentonite is present it is often best to leave it out. Recipes having high percentages of ball clay or kaolin might work best with less Veegum. Keeping good notes (with pictures) is essential to reach the objective here: Good brushing properties. We always use code-numbering (in our group account at Insight-live.com) and write those on the jars and test pieces. This is so worthwhile doing that I make quality custom labels for each jar!

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DIY glazes can do something commercial ones cannot:

Go on evenly, in one coat and dry in seconds.

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Commercial brushing glazes are laced with CMC gum to make them paint on thin and dry slowly. Why would anyone want that? Layering. Brushing on layers takes time and it is difficult to get even coverage, but it justifies brushing up the prices also!

What if you are not a "layer slayer" and want the opposite of all of that: Go on thick enough at one go, dry in seconds and apply super even. DIY potters have that ability by making thixotropic dipping glazes. You cannot buy these because the gum kills thixotropy. Thixotropic glazes are fluid in the bucket but gel after a few seconds of standing. This enables really good dipping properties - the gelling enables the glaze to stay in place upon extraction from the bucket. This picture demonstrates how such glazes hang on to even a non-absorbent and wet surfaces.

Bottom: Extreme thixotropy. The spatula is held vertical by gelling only. Yet when this slurry is put in motion, it is fluid!
Top left and right: These spatulas were slowly extracted and the engobe and glaze just hang on in a perfectly even layer. On a bisque surface, the glaze dries quickly, within seconds. And the engobe hangs on to leather hard ware for perfect coverage, even around sharp contours.

The next supply crisis will hit commercial glazes first.

Cope better this time by knowing DIY glaze mixing.

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As potters, we learned that no one is affected by supply chain problems more than prepared glaze manufacturers; they have complex recipes that require complex supply chains. It wasn't just availability; product consistency was also affected. It is again time to think about DIY, to start learning how to weigh out the ingredients to make at least some of your own. Arm yourself with good base recipes that fit your clay bodies (without crazing or shivering). Add stains, opacifiers and variegators to the bases to make anything you want. Admittedly, ingredients in your recipes can also become unavailable! But DIY as about options. When you "understand" glaze ingredients and what each contributes to the recipe and oxide chemistry, you are equipped to go well beyond weathering material supply issues. You will improve recipes, not just adjust them, to accommodate alternative materials. It is not rocket science; it is just work accompanied by organized record-keeping and good labelling.

Two methods to make your own low SG brushing glaze.

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Dipping glaze applies and dries in seconds. Brushing glazes dry slowly and dry hard. Brushing glazes simply have gum in the recipe, dipping glazes typically do not. This is the Alberta Slip cone 6 base, made jet black with 4% black ceramic stain (our code G3914A). We normally mix this as a dipping glaze but I have made a 500ml jar of low SG brushing version using both of the following methods. These methods will work for almost any glaze recipe (for those having exceptionally high clay content less Veegum is needed).

1) Shake together, in a plastic bag, 340g of mixed glaze powder with 5g of Veegum and 5g of CMC gum. Add that to 440g of water in a kitchen blender and mix on high speed until it gels (the gums resist mixing so the highest speed for at least 30 seconds is needed to prevent lumps).

2) Take 680g of dipping glaze (assuming it is about 50:50 water:powder you get 340g of dry), put that in the blender with another 80g of water and proceed as in method 1. Less total water is being used because the dipping glaze might not be exactly 50:50 water:powder. During mixing, if it gels too much add the extra 20g of water.

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

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Potters are used to making dipping glazes that they weigh out and mix from recipes. Hobbyists commonly use bottled commercial brushing glazes. Did you know that a dipping glaze can be turned into a brushing glaze by the addition of Veegum (or Veegum CER) and water? Do you know what a base-coat dipping glaze is? Here is a quick overview: Dipping glazes need to go on to bisque ware evenly, be thixotropic enough to hold on at thickness and drain and dry quickly. But they don't need to dry hard. Brushing glazes need a cohesive slurry that dries slowly and hardens well on drying. They also must adhere to the body really well so that multiple layers can be applied (individual layers go on thin). Base-coat dipping glazes are in between, they need to dry fast enough and gel well enough to make application by dipping possible (although less practical) and they need to adhere well enough to tolerate another layer without letter go of the body.

Control gel using Veegum, brushing properties with CMC gum

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This is G1214Z1 brushing glaze (with 5% titanium added). For a 340g powder batch (to get a pint) my initial target is 5g CMC gum and 5g Veegum. CMC controls drying speed and Veegum the amount of gelling. I first mix the CMC with the powder and shake the whole batch in a plastic bag. Then I add it all to 440g of water in the blender jar and mix it well (making sure no agglomerates remain (stage 1). Stage 2 is adding the VeeGum slowly, while high-speed blender-mixing, this is important because it enables tuning the degree of gel (which cannot be predicted). Because this recipe has little clay, it took all 5g of Veegum without overgelling (the entire mass moved freely in the mixer jar). But it did gel overnight (so 4g would be better next time). By contrast, it is the brushing behavior that demonstrates whether the amount of CMC is right. Not enough and coats dry too fast and go on too thick. Too much and it dries too slowly and too many coats are needed.

Here’s how we make a base brushing engobe

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This brushing engobe is thick and gooey (because it contains CMC gum), so it is practically impossible to sieve. Our regular propeller mixer is not able to break up the tiny agglomerates of New Zealand kaolin. But 30 seconds of blender mixing makes it as smooth as silk. To make this liter of brushing engobe we use 800g of powder and 10g of CMC gum in 800g of water. Because of the very high clay content this does not require Veegum to gel it. The CMC gum greatly improves the brushing properties. It also thins the slurry enough to enable its lower-than-normal water content, making it more suitable for painting onto leather-hard ware, minimizing the number of coats needed.

Make and sell your own jars of glaze at your teaching studio

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Your studio or workshop can save a lot of money making and even selling your own brushing glazes to students (at least for common colors and types). The supplies shown here enable printing quality labels on ordinary paper and applying them to jars that cost less than $2. We make the labels by ink-jetting onto regular paper, cutting them 62mm wide (2 7/16") and holding them securely in place using 2 7/8" transparent packing tape.

What about the glazes themselves? Just do what glaze companies do: Add stains to a base transparent glossy or matte glaze (for example G1916Q for cone 04 or G2926B for cone 6). Each 16oz jar needs 350g powder, 450g water, 5g CMC gum and 5g Veegum (leave out the Veegum and use less water for thicker coats). Stains are expensive (5-20 cents/gm here in 2024), at 7.5% (25g) that is $1-5 per jar. The materials for the G1916Q base cost $10/kg, and for G2926B $4/kg. Thus each jar costs $3.33 and $1.33 respectively. 5000g batches would make 15 jars. A best-case is about $5/jar, worst case about $10/jar (compare that with commercials that are about $15-70). Of course, you can save money by looking for deals on materials and stains and recycling jars. Consider other advantages of making your own: You can tune the rheology and adjust recipes to fit your clay bodies (to prevent crazing or shivering) and application methods.

Are you worried about labelled, testing and SDSs? Take a look at ASTM D-4236 and see if you still need to worry.

The secret to brushing glazes on large pottery items:

Pour-feed the brush in one long stroke.

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On the left I applied pure Ravenscrag slip, as a glaze, inside and out, using only a small brush. I did the same to the bowl on the right, using the G1947U transparent glaze. Both of H550 clay. We almost always use these as dipping glazes. But here I mix them as brushing glazes, adding 10g CMC gum powder to one liter of a water-reduced version of the slurries. Blender mixing makes it possible to mix in the powdered gum and tune water content for the best brushing experience. The gum slows down the drying speed dramatically so there is plenty of time to brush it into place (while the wheel is turning). The gum also greatly increases the cohesion, enabling pouring out of a pitcher in a long thin stream. In this firing I also glazed a leather hard 40-inch tall vase and a 35 lb bone-dry bowl using the same technique. The evenness of coverage was the best I have ever gotten (of any technique) on large sizes and shapes.

It might surprise you that handmade tile is often glazed using brushing. A glaze can be squirted onto a tile and spread with a large brush in seconds. This can be done on a passing conveyor or in batches on a table.

Glaze large bowls inside-and-out by brushing:

By turning your dipping glaze into a brushing glaze

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This wheel-thrown bowl is large, heavy and thick walled. There are pouring techniques to apply different colored dipping glazes inside and out but they are cumbersome and slow. It turns out that the hobbyist way of glazing is actually better - by brushing. I make these 500ml jars of brushing glaze and tune the percentage of gums to get the right painting consistency and drying time. Applying multiple coats by brush takes only a few minutes and no wax resist or any other tools are needed. And it is easy to meet two glazes in a straight line at the rim. On this piece, the inside glaze is G2936B and outside is G2926B. Both are almost always used as thixotropic dipping glazes, but nothing about such recipes disqualifies them from being mixed as brushing glazes.

Layer slayers and jar junkies

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Commercial brushing glazes have made it possible for hobbyists to glaze pottery on the kitchen table. But, the layering craze has seen these bottled products migrate into pottery studios and schools. In the minds of most, the glitter of expensive layering trumps all of the advantages of DIY. The "glam" of multiple can make the ugliest pot saleable. Here is the kind of pots an AI ChatBot told me it thinks we are making now:

• "Brush 'n Buffs" rely on lots of brush-on glaze layers for visual effect rather than technical finesse in form or glazing.
• "Gloss-Bosses" lean heavily on glossy, vibrant finishes to draw attention, often brushing up the prices to match.
• "Glaze Blazers" blaze a trail through high-end glazes to make a statement piece without much focus on craftsmanship.
• "Layer Slayers" layer glazes for that ‘artistic look’ rather than achieving mastery of the basics.
• "Jar Junkies" depend on store-bought, premixed jars to give their work aesthetic appeal.
• "Shelf Shockers" make pottery that looks striking on the shelf but might lack structural or functional finesse.
• "Costly Coaters" coat basic pieces in costly glazes, inflating prices as if each layer adds value.
• "Glitz Potters" put emphasis on glittery, glamorous finishes over solid craftsmanship.
• "Kiln Thrillers" focus looks alone, with beginners banking on decorative glazes for appeal.
• "Palette Pushers" pile on color layers as if painting rather than carefully curating glazes for effect.

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