Mason Stain Chart: Numbers, Names and Glaze Notes

How the Mason stain chart works

The Mason stain chart is a transcription of Mason Color’s online reference guide. Each stain has its current number, its old number where Mason lists one, its name, the elements Mason’s composition chart marks for it, and Mason’s notes. Those notes are numbered in the guide, so we’ve written each one out: “no zinc in the glaze”, “maximum firing 1260 °C” and so on.

Search matches every word you type, so “6600” finds Best Black, “teal” finds Teal, Dark Teal and Dark Teal Green, and “zinc” finds every stain with a zinc note. The colour group filter uses Mason’s own groups, from Pinks and Crimsons to Body Stains.

The swatches are approximate colours suggested by each name. Stain colour depends enormously on the base glaze, how much stain you add and how you fire, so a swatch is only a reminder of the general colour. The Print button gives you a tidy copy of whatever you’ve filtered, which is handy to pin above the glaze bench.

What do the notes on a Mason stain chart mean?

Mason’s notes tell you which base glazes and temperatures let a stain develop its colour. The most common is a maximum firing limit of 1260 °C, which covers all but a handful of the stains we list. The rest concern zinc, calcium and body stain use.

Zinc is the big one. Mason says zinc oxide influences colour in a glaze more than any other element, and that free zinc oxide in a glaze can destroy some colours. Nineteen stains carry “do not use zinc in glaze”, while others say zinc is optional, not necessary but better, or best left out. Mason also says zincless glazes generally shouldn’t contain magnesium oxide.

Calcium matters for a smaller group. Mason says the glaze must contain 6.7 to 8.4% calcium oxide, which is 12 to 15% calcium carbonate, for eleven stains: the chrome-tin pinks 6000, 6001, 6003 and 6006, the greens 6206, 6204, 6263 and 6264, the purples 6381 and 6385, and 6503 Taupe. Without enough calcium, those colours can turn muddy or brown.

Body stains and glaze stains

Mason stains can colour glazes, slips, engobes and clay bodies. Mason marks some as suitable for use as a body stain in porcelain at high temperatures, and says all its browns can be used in bodies, though their shade varies a lot with the body and the firing.

The guide also has a separate Body Stains group: 6020 Mn Al Pink, 6069 Fe Zr Coral, 6268 Cr Co Green, 6300 Co Blue, 6319 Mn Al Co Lavender, 6434 Fe Zn Yellow and 6485 Cr Sb Ti Yellow. Two of those numbers, 6268 and 6300, also appear among the glaze stains with different names, Sea Green and Mazerine. We list both as Mason does, so check the name as well as the number when ordering.

Colouring a clay body uses far more stain than colouring a glaze, so it’s usually reserved for small batches, slips and accents.

Coloured slips are a popular middle path. A stained slip brushed or trailed onto leather-hard ware gives strong colour with far less stain than a whole body, and it works well under a clear glaze. If you try it, test the slip on the clay you throw with, because a slip that shrinks differently from the body can crack or flake off in drying or firing.

Which Mason stains contain cadmium?

Mason’s composition chart marks cadmium and selenium in its bright reds, oranges and some yellows: 6021, 6025, 6026, 6027, 6028, 6030, 6088, 6097 and 6479 Sunshine. These are inclusion stains, where the colour is encapsulated in zircon to keep it stable in the firing.

Handle every stain as a fine ceramic powder: wear a suitable mask when weighing dry stain, clean up wet, and don’t eat or drink in the glaze area. For anything that will touch food, follow the stain and glaze makers’ guidance and local regulations, and have finished ware tested if in doubt. Our article on food safe glaze explains what to look for.

The composition column in the chart lists every element Mason marks for each stain, which also helps when you’re working out why a colour isn’t developing.

Testing Mason stains in your glaze

Test a stain in the exact base glaze you’ll use, at a few different amounts, on the clay you’ll use. A line of small tiles at increasing stain levels shows you where the colour saturates and where the glaze surface starts to change.

Mason also notes that firing temperatures can only be a rough guide. A slow firing to 2200 °F (about 1204 °C) may mature a stain like a fast firing to 2300 °F (1260 °C), and the cycle, atmosphere and cooling all affect the colour. So fire your tests in the same kiln and schedule as your work. If you don’t have a kiln, our kiln firing service in Mordialloc fires mid-fire glazes at cone 6. Our guide to Mason stains covers mixing them in more depth.

Common mistakes with Mason stains

The most common mistake is putting a pink or crimson stain into a zinc glaze, which can turn it a dirty brown. The second is skipping the calcium check for the stains that need it. The third is assuming a stain will look the same in every base glaze, when glossy, matte, opaque and clear bases can each give a different shade.

Another is trusting the number alone. Mason reorganised its colour chart in 2008, and a few numbers appear twice with different names, so confirm both the number and the name on the label against your notes.

Finally, weigh stains carefully. They’re strong, so a small weighing error changes the colour noticeably, especially in a small test batch. Use scales that read to a tenth of a gram for tests, write the exact amounts on each tile, and scale the recipe up only once a tile looks right.