FAQ

We recommend applying BOTZ glazes 2-3 times, unless stated otherwise in the instructions on the can. The two transparent glazes (9102 and 9106) and the two craquelé glazes (9351 and 9352) are applied, for example, only 1 time undiluted or 1–2 times lightly diluted. Red tones should generally be applied 3 times to ensure an intense color. For better application, BOTZ glazes can be diluted very well with a little water.

Wir empfehlen die Botz Glasuren 2-3 Mal aufzutragen, außer es steht etwas anderes unter den Hinweisen auf der Dose. Die beiden transparenten Glasuren (9102 und 9106) und die beiden Craquelé Glasuren (9351 und 9352) werden z.B. nur 1 Mal unverdünnt oder 1 – 2 Mal leicht verdünnt aufgetragen. Rottöne sollten in der Regel eher 3 Mal auftragen aufgetragen werden, um eine intensive Farbe zu gewährleisten. Für einen besseren Auftrag kann man die BOTZ Glasuren sehr gut mit ein bisschen Wasser verdünnen.

After purchase from us, glazes typically last 2-3 years on average - some considerably longer. Good storage conditions, meaning no large temperature fluctuations (no frost, no heat), extend shelf life. Thickened glazes can be stirred back to application consistency with water.

Tip: After use, clean the can rim well, add a little water to the can and stir this in at next use, or stretch cling film over the lid rim to also prevent the glaze from drying out.

The first firing (bisque firing) was traditionally between 850°C and 900°C. For powder glazes, a porous clay body was important so that the mixed powder glaze would adhere to the clay body. BOTZ glazes, however, work very well on higher bisque-fired ware because they contain a binder that ensures the glaze adheres firmly. Advantage of a bisque firing temperature at approximately 950°C: at a high bisque temperature, the clay's outgassing process is largely complete, and the glaze is not disturbed by clay gases in the second firing — meaning fewer bubbles and craters.

You can achieve beautiful results by applying one glaze over another. Mixing glazes together in the earthenware range does not always produce exciting results. Opaque glazes without effects work well (for example, the matte glazes 9107, 9108, 9487-9491, and 9612), and especially BOTZ stoneware (see Tips Stoneware in the current BOTZ catalog).

Red and gold tones in ceramics are often sensitive. BOTZ red tones (9601 – 9605) and BOTZ Gold (9541) are very stable if you follow 3 rules:

1) apply thickly, 2) fire low (up to 1040°C), 3) allow oxygen in the kiln, or don't pack pieces too tightly so air circulates well.

With Lava (9606) and Coral (9607) you can fire higher (optimal 1050°C), but you must monitor oxygen supply. White edges are characteristic of these glazes. A very resistant red is 9611 Lacquer Red.

This usually works very well, especially if you've applied the glaze too thinly and want to apply the same glaze again. Drying time on fired glaze is of course longer than on unfired clay body. If you apply a different color over a fired glaze, the result is not entirely predictable, but often exciting. For good adhesion, you can warm the fired ceramics to 60–100°C before re-glazing.

It is very important to know that every firing in ceramics, including a bisque firing, releases health-hazardous gases. You should extract these fumes using a ventilation system (for example, at www.kerablu.de) or ensure good ventilation in the kiln room and avoid working in the kiln room during firing. The sometimes strong odor from BOTZ glazes (approximately between 200–300°C) is not more dangerous than odorless-firing glazes. Use the odor as an indicator of insufficient ventilation. The odor load decreases if you let the glazes dry thoroughly before firing.

The term "food-safe" does not exist in ceramics. It is important to use only lead-free and, ideally, completely unlabeled glazes for dinnerware. We subject our glazes to acid and alkali testing according to DIN standards. Those glazes that pass the test receive the pictogram "Recommended for dinnerware" — that way you're on the safe side. Some glazes are not acid-resistant, meaning that in contact with mild acids, ingredients from the fired glaze can be dissolved. Therefore, we recommend not using these colors on the inside of dinnerware for safety reasons. For hygiene reasons, for example, effect glazes or matte glazes fall into this group because food residue could accumulate there.

BOTZ liquid glazes (earthenware) can be fired very well using firing curves that are usually already pre-programmed in your kiln controller — they do not require a specially entered firing curve. If you adjust manually: heat to approximately 600°C at approximately 150°C per hour, then fire at full power to maximum temperature 1020–1060°C with a hold time of 10–20 minutes.

All samples in the BOTZ catalog are fired at 1050°C with a 15-minute hold time (except red and gold). Please note that a kiln often fires hotter in the upper area than in the lower area.

Stoneware glazes should be fired at the same heating rate to 1220–1280°C with a 10–30 minute hold time; optimal final temperature here is 1250°C.

Frost resistance is primarily determined not by the glaze, but by the clay. When the clay is "sintered," meaning it is dense and can no longer absorb water, it is frost-resistant. Please ask your clay supplier about the sintering temperature of your clay.

We have some glazes in our program that are designed to run (see pictograms in the catalog). In that case, please apply the glaze very thinly to the lower area of your piece. If other glazes are running, it could be due to too thick an application or too high a temperature. You should check the actual kiln temperature reached using pyrometric cones (or Orton cones). We recommend protecting kiln shelves with a separator (e.g., BOTZ separator Art. No. 90108).