Barium Carbonate

It's toxic if swallowed, so treat it as one of the most hazardous materials in your studio. Wear gloves and a NIOSH-approved respirator (N95 or better) when you handle the dry powder. Don't eat or drink in the studio. Keep it sealed, labeled and away from children and pets, and clean up with a wet sponge. Use it only in tested recipes, and have functional ware lab-tested before you sell it.

Usually it's underfired, or the recipe has too little silica. An underfired barium glaze holds its barium less well than a fully melted one, so fire to the full cone and check the recipe.

Both help mid- and high-fire glazes melt and can give satin surfaces. Barium carbonate gives the most intense copper blues, but it's toxic if swallowed and needs careful handling. Strontium carbonate is much less toxic and the usual stand-in. Start with 7.5 grams of strontium for every 10 grams of barium, and fire test tiles of both versions side by side. Colors, especially copper blues, won't match exactly.

Glaze and clay recipes go by weight, not by volume, and they don't count water. Each ingredient is a share of the dry total. 2% means 2 grams for every 100 grams of dry ingredients. For a 500-gram batch, that's 10 grams. Colors and opacifiers are often listed as extras on top of a recipe that adds up to 100, written like "+2" or "add 2%." Weigh those the same way: 2 grams for every 100 grams of the base recipe. A digital scale that reads to 0.1 gram makes small amounts easy.

A test tile is a small piece of the clay you use, glazed and fired just like your real work. Raw materials vary from bag to bag, and results also change with your clay, how thick you apply the glaze and how your kiln fires. A test tile is the only way to know what you'll get before you glaze a whole batch of pots. Write what's on each tile on the back (an underglaze pencil works), and keep notes so you can repeat what works.

Yes, whenever you handle the dry powder. Fine dust is the main hazard with most raw materials, and some can harm your lungs over time. Wear a NIOSH-approved respirator (N95 or better) while you weigh and mix. A basic dust mask that isn't N95-rated won't protect you. Once a material is mixed with water, dust is much less of a problem, but wipe up spills with a wet sponge before they dry, and mop instead of sweeping. Don't eat or drink while you work, and wash your hands afterward. Check each product's Safety section for anything extra that material needs.