Barium carbonate is one of the raw glaze materials that sits on many recipe sheets and makes new potters nervous, with good reason. It gives effects that are hard to get any other way, and it is also toxic if swallowed. This guide explains what barium carbonate does in glazes and clay, what the safety data sheet (SDS) says, and how to handle, store and use it in a home studio.
It is research-based: we read supplier SDS sheets, Digitalfire's material and oxide pages and published studio safety guides. We did not mix or fire barium glazes ourselves. For the full family of raw materials, see our glaze materials guide.
What barium carbonate is
Barium carbonate is a fine white powder, chemical formula BaCO3. Its mineral form is called witherite. Digitalfire lists it as about 77.7% barium oxide (BaO) with about 22% loss on ignition, which is the carbon dioxide that burns off in the kiln. That loss matters when you compare it with other barium sources, because a recipe calls for the carbonate weight, not the oxide.
US pottery suppliers sell it by the pound, usually in small bags or tubs for hobby use. It does not dissolve much in water, but it does dissolve in acids, and that is where the hazard comes from.
What barium carbonate does in glazes
Potters use it for four main jobs.
Satin and crystal matte surfaces
Barium is best known for silky matte glazes. As the glaze cools, barium helps tiny crystals form across the surface, which scatter light and give a soft, buttery feel. Digitalfire notes that the result depends on the base glaze, the peak temperature and the cooling speed, so the same recipe can come out glossy in one kiln and matte in another. For mattes in general, including ones made without barium, see our matte glaze guide.
Color: copper blues and turquoise
With copper, barium pushes the color toward strong blues and turquoise mattes instead of the greens copper usually gives. Digitalfire points out that barium is a poor choice for chrome greens and iron reds, so it is not a general color booster.
A flux at mid and high fire
Barium oxide helps melt a glaze, but Digitalfire describes it as not active at low temperatures. It does most of its work in mid-fire and high-fire glazes. It also releases gas as it breaks down, which can cause pinholes and blisters if a glaze carries a lot of it.
In clay bodies: stopping scum
Some clay makers add a very small amount, which Digitalfire gives as roughly 0.2 to 0.8%, to clay bodies. It locks up soluble salts that would otherwise travel to the surface as a white scum (efflorescence) on red earthenware, brick and tile. If your terracotta clay lists it, that is why.
Source conflict on temperature: Wikipedia lists barium carbonate as decomposing from about 2,480°F (1,360°C), while Digitalfire lists decomposition starting from about 1,877°F (1,025°C) and melting from about 2,480°F (1,360°C). The practical point is the same in both: the gas comes off late, during the glaze melt.
Barium carbonate hazards from the SDS
Every supplier must provide an SDS. The two we read, from Chemical Products Corporation and one posted by Archie Bray Clay, agree on the main hazard.
| SDS item | What it says |
|---|---|
| Classification | Acute toxicity, oral, Category 4 |
| Signal word | Warning |
| Hazard statement | H302: Harmful if swallowed |
| Other warnings | The Chemical Products Corporation SDS also says harmful if inhaled and may cause eye and skin irritation |
| Key precautions | Wash skin after handling; do not eat, drink or smoke when using; if swallowed, call a poison center or doctor |
| Exposure limit | OSHA PEL and ACGIH TLV 0.5 mg/m³ as barium (8-hour average), per the Archie Bray SDS |
| Protection listed | NIOSH-approved respiratory protection for dust; gloves (PVC, natural rubber or neoprene in the Archie Bray SDS); safety glasses or goggles |
The real risk in a home studio is swallowing it by accident: dust on hands, a mug of coffee on the mixing bench or powder carried into the kitchen. Inhaled dust is the second route. Read the SDS that comes with your bag, sections 2 (hazards), 7 (handling and storage) and 8 (protection), because the exact wording varies by supplier.
How to handle barium carbonate at home
- Get the SDS first. Ask your supplier for it if it is not on the product page, and read it before opening the bag.
- Wear a fitted NIOSH-approved respirator rated for dust while you scoop and weigh it. Most glazes also contain silica, which is its own lung hazard.
- Wear gloves and eye protection. Nitrile or the glove materials your SDS lists, plus safety glasses or goggles.
- Weigh it into water. Add the weighed powder straight to the water in your glaze bucket so it stops being dust as soon as possible.
- Clean up wet. Wipe the scale, bench and floor with a damp sponge or mop, or use a HEPA vacuum. Never dry sweep or blow dust off a bench.
- No food or drink in the room. Wash your hands and forearms before you eat, drink, smoke or touch your phone.
- Keep work clothes in the studio. Wash them separately so dust does not reach the rest of the house.
Our clay dust safety guide covers respirators, HEPA vacuums and wet cleaning in more depth.
Storage and disposal
- Keep it in its original bag inside a sealed, clearly labeled container, as the SDS asks, in a dry place.
- Store it away from food, kitchen items and anything a child or pet can reach. A locked cabinet or high shelf is ideal.
- Never decant it into food containers or unlabeled jars.
- The Chemical Products Corporation SDS warns that emptied containers may still be toxic. Bag them before throwing them out.
- Do not rinse glaze buckets or barium powder into a drain. Let rinse water settle, as you would with a clay sink trap, and dispose of the solids following your local household hazardous waste rules.
Barium glazes and food: why to be careful
Do not assume any barium glaze is food safe on your pots. Digitalfire explains that glazes carrying a lot of barium may not lock all of it into the glass, so acidic foods and drinks such as coffee, citrus, tomato and wine can leach it out. Florida State University's ceramics safety guide notes that barium has leached in hazardous amounts from some glaze formulas. Whether a glaze leaches depends on the full recipe, the clay, the application and firing to the stated cone, and the only way to know is a lab leach test on your fired pots.
Many studios simply keep barium glazes for outsides, decorative ware and sculpture, and use a tested liner glaze inside mugs and bowls. For how food-safety testing works, see our food safe glaze guide.
Alternatives: strontium carbonate and barium frits
Many potters swap barium for strontium carbonate to lower the toxicity concern, and Wikipedia notes that this substitution is common. It is not a straight one-for-one swap: Digitalfire notes that strontium reacts earlier in the firing and may give a smoother surface, so color and matte quality can change. Make test tiles before switching a glaze you like.
The other route is a barium frit, where the barium has already been melted into glass and ground. Digitalfire names Ferro CC-257 and Fusion F-403 as barium frits and notes that frits supply barium with fewer firing defects. Frits can lower dust and solubility concerns, but a frit-based glaze still needs its own testing for food use. Our frit guide explains how frits work.
Buying barium carbonate
Pottery suppliers that sell raw materials list barium carbonate by the pound, and some sell small 1 to 5 pound bags that suit hobby test batches. Buy only what a recipe needs and ask for the SDS with the order. Our pottery supplies guide lists US suppliers that sell raw materials.
If you only want a barium-style matte and do not plan to mix glazes from powder, consider a commercial matte glaze in a jar instead. You avoid handling the raw powder entirely.
Common mistakes
- Weighing barium carbonate without a respirator because "it is only a few grams."
- Mixing glazes in the kitchen or on a table used for food.
- Using a high-barium art glaze on the inside of mugs and bowls.
- Swapping strontium carbonate in at the same weight and expecting the same glaze.
- Dry sweeping spilled powder.
- Storing it in an unlabeled tub where someone could mistake it for something else.
What you need
Before you buy barium carbonate, set up a fitted NIOSH-approved respirator, gloves, safety glasses, a digital scale, a sieve, lidded buckets and a lockable storage spot. Our pottery supplies guide covers where to buy raw materials and studio basics, and the glaze materials guide explains the other ingredients in a barium recipe.
Sources: Barium carbonate SDS from Chemical Products Corporation and the barium carbonate SDS posted by Archie Bray Clay (hazard classification, H302, precautions, exposure limits, protection, storage); Digitalfire material page for barium carbonate and oxide page for BaO (composition, mattes, color response, clay body use, leaching, frits); Wikipedia entry on barium carbonate (witherite, uses, decomposition); Florida State University ceramics health and safety guide; Hawaii Potters Guild article on glaze toxins. Specs checked October 2026.