•The secret to cool bodies and glazes is a lot of testing.
•The secret to know what to test is material and chemistry knowledge.
•The secret to learning from testing is documentation.
•The place to test, do the chemistry and document is an account at https://insight-live.com
•The place to get the knowledge is https://digitalfire.com
Glaze Hardness - GLHD
This test procedure was employed in the Foresight Ceramic Database and now is available for those having an account at Insight-Live.com.
Accumulating test data using the variables defined in these procedures enables us to create tools that enable you to compare the physical properties of materials and recipes.
If glazes are underfired or have an unbalanced formula (i.e. lack silica:alumina) they can be soft enough to 'cutlery mark', that is, scratchor mark by metal instruments.
Glaze Hardness Testing Procedure
Method 1: Using a sharp-pointed concrete nail or dry-wall screw, attempt to scratch the surface of the glaze in question. Also watch for any tendency of the glaze to chip, for small holes to develop as a result of under-the-surface bubbles, and for any black marks that show up. Compare its response with that of a glaze known to be good.
Method 2: Using a standard sharp hack-saw blade attempt to 'saw' an area of the glaze surface. Watch for scratches that develop and for black marking. Compare the glaze's response with that of a glaze know to be hard.
If marks, pits, or scratches are left by either method, attempt to clean the surface. If it cannot be cleaned, reject the glaze for food or drink surfaces
VAL - Value (V)
Out Bound Links
In Bound Links
GLFL - Glaze Melt Flow - Runway Test
By Tony Hansen