In the Studio: Group Studio Glaze Management Brian Grow

Appears in the Nov/Dec 2018 issue of Pottery Making Illustrated.

A community/group studio, by its nature, has a significant number of variables—not least of which is the glaze palette. Different students will want different colors and properties for their glazes. The key is to find a happy balance by offering enough options without overburdening the system.

The studio needs to offer a glaze palette that runs from dark to light, glossy to matte (satin), and from opaque to breaking and translucent. You need these glazes to play nicely with each other. And, you need the glazes to be forgiving in application, as you’ll have people with a variety of skill levels working with them.

At the Workhouse Art Center (www.workhouseceramics.org), in Lorton, Virginia, our glaze palette consists of 12 core glazes (1), as well as 1–2 mystery glazes that are combinations of test glazes, mixing mishaps, and contaminated glazes. Many of these glazes are developed using the same base recipes, which helps to cut down on the number of materials we need in stock (2). We also use a few slips that complement those glazes, providing students with more options

The Glaze Team

Our glaze area is run by a volunteer team. The Workhouse Glaze Team consists of 5 to 6 volunteers or assistants. To be an assistant, you must be a registered student. You must also obtain and wear an approved respirator. All assistants are given 24-hour studio access as compensation for their work.

Each assistant is assigned a stable of glazes, slips, and/or oxide washes to maintain. That responsibility includes regulating the specific gravity of the glazes in the buckets, as well as monitoring glaze levels and quantities. Assistants mix a new batch when a glaze hits a predetermined refill level, denoted by a fill line on the bucket. The assistant is also responsible for making test tiles of new batches before adding the new glaze to the bucket that is in the glazing area. We refer to these as the floor buckets (see 1).

Glaze Recipe Consistency

Consistency, both in terms of glaze availability and how those glazes are mixed, is essential. You have to set a mixing procedure and adhere to it. For example, at what point should a glaze be replenished? What is the proper or preferred thickness (specific gravity) of each glaze? Think across the board, and strive to build a system that works for all.

Create a recipe book that contains only active studio glazes. A separate book or folder should be kept for tests and old glaze recipes. Writing recipes with a consistent format helps provide clarity. We have our glaze recipes written in 7500-gram batches (3), which makes slightly more than ¾ of a 5-gallon bucket of glaze. This quantity is sufficient enough to top off our floor buckets and leave a bit for restocking later. Our glaze recipes include a checklist so that ingredients can be marked off as weighed and added. They also have a place for the batch date so that we can track usage. The top of the recipe has the specific gravity reading. The recipe sheet becomes a clear record of that particular glaze.

Glaze Making Procedure

We have a specific procedure for weighing out glazes, which enables us to ensure consistency as we rotate new people through the team. The procedure is posted and clear (4). Dry ingredients are weighed out (5) (we primarily use a triple-beam balance) and placed into a container. A water estimation is placed in a separate bucket—I start with a pint of water per 1 pound of dry glaze. Dry ingredients are sifted into the water—on occasion I’ll use a glaze blunger to expedite the mixing process.

The glaze is then sieved and water is added to bring the mix to the listed specific gravity (6) by checking with a hydrometer, making sure to dry the hydrometer between each test. Once we have the desired thickness, we immediately dip test tiles of each studio clay body into the new batch of glaze and label the tiles.

Each bucket of glaze gets labeled with its name and mixing date both on the lid and on the bucket, then it’s set aside to wait for the test tiles to be fired. The tiles are cycled through a studio firing, and then compared to the studio tile board (7). If they match up, then the glaze can be folded into studio use. When combining the new mix and the studio floor bucket, we sieve them together and adjust the specific gravity if necessary.

Keeping a community- or group-studio glaze operation running dependably takes attention and planning. You choose a glaze palette, create a tile board so students/artists can have realistic expectations, establish proper thicknesses for glazes (this is key), and decide glaze refill levels to avoid disappointment. Then you follow the cardinal rule: everything gets tested.

Brian Grow is a resident artist and the glaze team manager at the Workhouse Arts Center in Lorton, Virginia.