|Monthly Tech-Tip |
Here is how to prepare a melt-flow ball for the GBMF test or the GLFL test: Weigh 11g of the frit and 0.33 of Veegum (the latter plasticizes the frit and imparts dry hardness). Put them in a small ziplock bag. Zip it to entrap air, roll the zipper down to inflate it and shake well to mix the Veegum and frit. Stir the powder into plenty of water in a small bowl. A brush works best for quick delumping and cleaning out the bowl when pouring on to a plaster slab. It dewaters very quickly, after about 10 seconds, just as the water sheen is gone, peel it up with a rubber rib. Smear it back down and peel it up every few seconds until it is plastic and formable (not sticky). Roll it into a ball, label it and dry it under a heat lamp (could take an hour, the Veegum really holds on to the water). When dry use a sharp knife to cut off enough to bring it down to 10 grams.
Glaze Melt Fluidity - Ball Test
A test where a 10-gram ball of dried glaze is fired on a porcelain tile to study its melt flow, surface character, bubble retention and surface tension.
Glaze Melt Flow - Runway Test
A method of comparing the melt fluidity of two ceramic materials or glazes by racing them down an inclined runway.