Cone 6 Whiteware/Porcelain transparent glaze
Recipe
Notes
A cone 6 transparent general-purpose base recipe developed by Tony Hansen (see link to go there below, it contains technical and mixing information about the recipe). This page contains technical and mixing information about the recipe, their page, under code MG6CG, contains mixing and usage information. Page shares at Insight-live.com have information on the development of this from the original recipe (as well as adjustmentsto lower thermal expansion e.g. G2926S). This is an adjustment to Perkins Studio Clear G2926A (this contains much more SiO2 and uses a frit instead of Gerstley Borate as the boron source). It is just as glossy and transparent, has a less fluid melt (thus will be more durable). With this change, this is a really stunning transparent glaze. We have found that this will even tolerate 5% more silica, yet still smooths out well (more silica produces a more durable glass). We almost always fire pieces using the C6DHSC firing schedule. That alone greatly reduces surface defects and gives better gloss. If you can also ball mill the glaze, it will be even better (more transparent, more durable, more glossy, less likely to craze). This is because 200 mesh particles of silica usually do not likely completely dissolve in the melt thus cheating the chemistry of needed SiO2 (ball milling breaks them down). Another option is to use 325 mesh silica. In our testing, this glaze survives a 300F oven-to-icewater test without crazing on Plainsman M370 (25-Porcelain using Nepheline, Tile#6 Kaolin, silica and Old Hickory ball clay. It is less affected than the original when the application is too thick (minimal bubbles and crazing). If you just want to mix it the traditional way, then start with 90 water to 100 powder (by weight) and agitate well using a propeller mixer. Then add more water until it is creamy, try it, adjust, etc. However, this recipe has the best suspension and application properties when it is thixotropic (that involves mixing it thinner than normal and gelling it using Epsom salts). Target a specific gravity of 1.43-1.44 (equal weights of water and powder should be slightly above this). Then about add 1g of Epsom salts per 1000g powder to increase thixotropy. This should make it creamy and it should gel after a few seconds on standing still (add more Epsom salts if needed but be careful, it is easy to over-do it). Since the slurry is not too far from 50:50 water:powder, add colors and opacifiers on that basis. For example, 1000g of slurry has about 500g of powder. Thus for white 10% pacifier would be 50g. This is approximate but suitable for testing. Later if you decide a mix has promise then mix-from-scratch with the right percentages. Screen through 80 mesh (tiny wollastonite agglomerates are possible, they will not break down without screening). Plainsmanclays.com makes this recipe as a premixed powder. The glazes section on their site has additional info. If this crazes ball milling will help (assuring that all silica grains dissolve and do their work to low thermal expansion). Otherwise, see the links below. This glaze melts early, it may not be suitable for decals (we have had successes and failures with decal firings to cone 022). The problem occurs when tiny sharp-edged blisters form on the surface. The reason for the problem is the high B2O3 (to reason why it melts so well). A solution is to blend in some G2934 matte (its B2O3 is less that 1/3 as much). Since the glossy is dominant, even a 50:50 mix is still likely to be glossy.
Description
A base transparent glaze recipe created by Tony Hansen, it fires high gloss and ultra clear with low melt mobility.