Brushing glazes on large pottery items is surprisingly practical

I applied this cone 10R transparent inside and out on both bisque and bone-dry ware using only a small brush (of course a larger one or a fan brush would be better). I have done up to 35 lb bowls this way. This is not a commercial brushing glaze, that would be super expensive for large pieces. This is a dipping glaze that we mix ourselves: G1947U. We add 10g CMC gum to one liter of a water-reduced version of the slurry. Blender mixing makes it possible to mix in the 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 it without drips, even in a long thin stream. Many pieces were done like this in recent kiln loads (including application onto a leather-hard 40-inch tall vase), the evenness of coverage was the best I have ever gotten (of any technique).

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Add CMC gum to a dipping glaze slurry for brushing

The outsides of these reduction fired bean-pots are a unique challenge to glaze evenly and drip free using dipping or pouring. I have to get glaze on evenly all around the handles. And a much thinner layer is needed inside the flange. A gummed brushing glaze is a solution. But how can one convert a cup of dipping glaze into a brushing glaze? CMC gum powder, 1.5% - it slows down drying and adds brushing properties. But, it makes some glazes watery so a gelling agent is also needed. But, assuming that does not happen here (this is pure Alberta Slip) and that our glazes are about 50:50 water:powder, I can blender-mix 3.75g CMC gum powder into 1000g of slurry to get the 1.5% concentration. Triple-layer brush-glazing this piece takes about five minutes. I use two brush types (fan and hake) and different techniques for each zone. It dries really hard. What if the gum over-thins the glaze, detrimentally affecting brushing properties? A water-reduced version is needed. Dipping glaze normally settles somewhat on standing and the water layer can be poured off (or removed using a flat-faced sponge). Then extract a cup, measure the slurry water content, and add CMC based on that.

Glazing large bowls inside-and-out using brushing glaze

This wheel-thrown bowl is large, heavy and thick walled. There are pouring techniques to apply different colored dipping glazes to the 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 painting consistency and drying time best for me. Applying multiple coats by brush took only a few minutes and no wax resist or any other tools were needed. And it was easy to meet the two glazes in a straight line at the rim using the brush. The inside glaze is G2936B and outside is G2926B.

Links

URLs	https://youtu.be/-f-skGLVyMg Youtube Video: Brush Glazing Large Pieces

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