A practical guide to barium carbonate, why brick makers use it to stop scumming, how it differs from barium sulfate, and how it is supplied, from a US-based distributor.
Barium carbonate (BaCO3, CAS 513-77-9) is a white powder used in ceramics, glass, and brick manufacture. In brick it locks up soluble sulfates that would otherwise surface as scum; in glass and ceramics it modifies the melt and improves refractive index and glaze quality. Unlike barium sulfate it is toxic if ingested, so handling matters. Stratus Chemical supplies industrial grade across the United States.
| Property | Value |
|---|---|
| Chemical name | Barium carbonate |
| Synonyms | Barium monocarbonate, witherite (natural mineral) |
| CAS number | 513-77-9 |
| Molecular formula | BaCO3 |
| Molecular weight | 197.34 g/mol |
| Appearance | White powder |
| Water solubility | Practically insoluble; soluble in dilute acids |
| Grades supplied | Industrial |
| Packaging | Bags, supersacks |
| Documentation | COA & SDS provided on request |
The figures below are representative of industrial grade barium carbonate. They are indicative rather than guaranteed: specifications vary by source and by lot, and the certificate of analysis for your material governs.
| Test | Specification |
|---|---|
| Description | White powder |
| Purity of BaCO3 | 98.50 to 99% min |
| Acid insoluble in HCl | 0.10% max |
| Water soluble sulphide (as BaS) | 0.20% max |
| Residue on 300 mesh sieve | 0.10% max |
| Fe2O3 | 0.050% max |
| Moisture | 0.25% max |
| Alkaline and other metal sulphates | Not more than 0.20% |
Barium carbonate is a white, dense powder, occurring naturally as the mineral witherite and produced commercially from barite. It is practically insoluble in water but dissolves readily in dilute acids, and that difference is the single most important fact about it, both for how it works and for how it must be handled.
In ceramics and glass it is valued as a source of barium oxide, which enters the melt and changes its behaviour. In brick it is valued for something else entirely: its ability to react with and immobilise soluble sulfates.
This is the application that accounts for much of the tonnage and the one most worth understanding, because the mechanism is neat and the alternative is an expensive cosmetic defect.
Clays used for brick contain soluble sulfate salts, principally calcium and magnesium sulfates. During drying and firing, water migrating to the surface carries those salts with it, and when the water evaporates the salts are left behind as a white deposit. In the trade this is scumming, and on the finished wall it is efflorescence. It does not weaken the brick, but it ruins the appearance and customers reject it.
Barium carbonate added to the clay body reacts with those soluble sulfates to form barium sulfate, which is one of the least soluble compounds in ordinary use. Once converted, the sulfate cannot migrate to the surface because it can no longer dissolve. The problem is eliminated at source rather than cleaned up afterward.
Addition rates are set against the sulfate content of the specific clay, which is why the material is dosed from a clay analysis rather than a standard recipe. Fineness matters as well: the reaction depends on the barium carbonate being distributed intimately through the body, which is why the residue-on-sieve line appears on the specification.
Added to clay bodies to eliminate scumming and efflorescence, as described above. The dominant use in many markets.
Barium oxide acts as a flux and produces the characteristic matte surfaces that many glaze formulations aim for, as well as improving hardness and chemical resistance.
Used to raise refractive index and density, improve chemical durability, and help refine the melt. It appears in optical glass and specialty glass formulations.
Barium carbonate is a raw material for other barium compounds, is used in ferrite magnet production, in some cement and refractory applications, and in the treatment of certain process streams to remove sulfate.
| Property | Barium carbonate | Barium sulfate |
|---|---|---|
| Behaviour in acid | Dissolves readily, releasing barium ions | Does not dissolve |
| Toxicity | Toxic if ingested; treat as a hazardous material | Essentially benign because it is insoluble |
| Typical role | Chemically active: fluxes, reacts, supplies barium oxide | Chemically inert: filler, extender, weighting agent |
| Main markets | Brick, ceramic glazes, glass, ferrites | Coatings, plastics, drilling fluids, shielding |
The two are frequently confused because the names are similar and both are white barium powders, but they behave in opposite ways. Barium sulfate is chosen precisely because it does nothing; barium carbonate is chosen because it reacts. Substituting one for the other does not produce a slightly different result, it produces no result at all. See our barium sulfate guide for the inert side of that comparison.
Store barium carbonate dry in closed original packaging, off damp floors and away from acids. It is stable in storage and the routine practical problem is caking after moisture pickup.
Barium carbonate is toxic if swallowed. Although it is insoluble in water, stomach acid dissolves it and releases soluble barium, which is the reason it is treated as a hazardous material while barium sulfate is not. Do not let familiarity with barium sulfate set expectations for this product.
Handle the dust with the ventilation, respiratory protection, and personal protective equipment specified in the Safety Data Sheet. Avoid dry sweeping of spills, keep the material away from food and drink and from any acid, and observe normal industrial hygiene including washing before eating. Follow the SDS for the specific grade.
Barium carbonate is used principally in brick and heavy clay manufacture, where it prevents scumming and efflorescence by locking up soluble sulfates in the clay. It is also used in ceramic glazes and frits as a flux and matting agent, in glass manufacture to raise refractive index and durability, in ferrite magnet production, and as a raw material for other barium compounds. Stratus Chemical supplies industrial grade across the United States.
The CAS number for barium carbonate is 513-77-9. Its molecular formula is BaCO3 and its molecular weight is 197.34 g/mol. It is also known as barium monocarbonate and, in its natural mineral form, as witherite.
Clays contain soluble sulfate salts that migrate to the surface with water during drying and firing and are left behind as a white deposit when the water evaporates. Barium carbonate added to the clay body reacts with those soluble sulfates to form barium sulfate, which is among the least soluble compounds in ordinary use. Once converted, the sulfate can no longer dissolve and therefore cannot migrate to the surface. Addition rates are set from an analysis of the specific clay rather than a standard recipe.
They behave in opposite ways despite the similar names. Barium carbonate dissolves in acid and is chemically active, which is why it fluxes glazes, reacts with sulfates in clay, and supplies barium oxide to a glass melt. Barium sulfate does not dissolve and is chemically inert, which is why it is used as a filler, extender, and weighting agent. Barium carbonate is also toxic if ingested while barium sulfate is essentially benign, and that difference comes from the same solubility distinction.
Yes, it is toxic if swallowed and should be treated as a hazardous material. Although it is practically insoluble in water, stomach acid dissolves it and releases soluble barium. This is the key difference from barium sulfate, which is insoluble under those conditions and is consequently benign. Handle the dust with the ventilation and personal protection specified in the Safety Data Sheet, keep it away from acids and from food and drink, and avoid dry sweeping of spills.
Because fineness governs how well the material reacts. In a brick body, barium carbonate has to be distributed intimately through the clay to meet and react with the soluble sulfates; coarse particles react incompletely and leave sulfate free to migrate. In a glaze, oversize particles can produce visible defects in the fired surface. The sieve residue line is a practical control on both.
Stratus Chemical supplies barium carbonate in bags and supersacks, in industrial grade, with a certificate of analysis provided for each shipment. Tell us the purity, fineness, and volume you need and we will confirm pricing and availability within one business day.
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