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Calcium Chloride

Description: Flocculant


Used as a flocculating agent in glazes (to suspend and gel them). For many, especially larger manufacturers, it is the product of choice (more effective than epsom salts and vinegar). It works well with glazes containing bentonite or carbonates. This material is the key to being able to apply a glaze to non-porous porcelain bisque ware, the slurry stays in place after application because of the gel state.

Usually small additions (.1-.3%) added to glaze slurries are sufficient to produce gelling. But sometimes higher, or considerably higher, percentages are needed (which may be an important consideration if small amounts of epsom salts would work).

One of our users reported that using Calcium Chloride in glazes containing bone ash can cause a hardpan to precipitate.

Calcium Chloride (CaCl2) is inexpensive and can be sourced from online chemical stores (e.g.; it may be listed as hazardous, placing restrictions on shipping). Pool supply places sell it as an adjuster for water hardness (keeps the acids they put in pools from attacking the pool plaster). Calcium chloride is used on sidewalks as an ice-melter in cold climates.

Related Information


Oxide Analysis Formula
Materials Epsom Salts
Materials Vinegar
Typecodes Generic Material
Generic materials are those with no brand name. Normally they are theoretical, the chemistry portrays what a specimen would be if it had no contamination. Generic materials are helpful in educational situations where students need to study material theory (later they graduate to dealing with real world materials). They are also helpful where the chemistry of an actual material is not known. Often the accuracy of calculations is sufficient using generic materials.
Typecodes Additives for Ceramic Glazes
Materials that are added to glazes to impart physical working properties and usually burn away during firing. In industry all glazes, inks and engobes have additives, they are considered essential to control of cohesion, adhesion, suspension, dry hardness, surface leveling, rheology, speed-of-drying, etc. Among potters, it is common for glazes to have zero additives.
Glossary Thixotropy
Thixotropy is a property of ceramic slurries of high water content. Thixotropic suspensions flow when moving but gel after sitting (for a few moments more depending on application). This phenomenon is helpful in getting even, drip-free glaze coverage.


Glaze SuspenderGels glaze slurries.
By Tony Hansen
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