Alkalis
Read this tip to make your life smarter, better, faster and wiser. LifeTips is the place to go when you need to know about Glazes and other Ceramics topics.
Alkalis
What are Alkalis?
Alkalis are the opposite of acids, potters call the glaze and body fluxes their alkalis. These are the non-colouring metal oxides which react with the acids in the presence of heat to produce silicates(glasses).
The so-called strong alkalis are:
Lithium oxide
Sodium oxide
Potassium oxide
Which are soluble in water. The weaker alkalis are partly referred to as aldaline earths or by the more general name of bases. They are:
Beryllium oxide
Magnesium oxide
Calcium oxide
Strontium oxide
Barium oxide
Zinc oxide
Cadmium oxide
Lead oxide
Bismuth oxide
They are not necessarily weaker in ceramic fusions but are less actively soluble in water.
They do not give the same bright colour response in glazes as the strong alkalis.
Alkalis release negatively-charged hydroxyl ions when dissolved in water. They have a sting and a re corrosive in a similar way to acids whilst being neutralized by the substances they meet. The soluble alkalis, soda ash and sodium silicate, are used to deflocculate clay for slip casting.
| Guru Spotlight |
| William Pirraglia |
