|Monthly Tech-Tip |
On the left is an ultra-white, doubtless containing 20% zircon. It smells bad and has settled out, indicating that mocrobials have degraded the gelling agent. The one on the right is bright yellow, it would contain significant encapsulated stain. These stains are troublesome, they seem to spawn the growth of a different bacteria, it smells much worse. And the slurry has literally gone rotten, turning black. Companies add biocides during mixing and try to minimize the amount used (since they are based on chloroform). But the many variables in materials and procedures will mean that some glazes will slip through the system and go bad. Of course, these products should be used relatively quickly after purchase, it is too much to expect many years of shelf life from them.
Ceramic glazes and clay bodies can host micro organisms. They can be just a nuisance, a source of worry or can render a product useless. What should you do?