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Hello, My white gloss glaze has recently started pinholing I believe. We have been using it for years with no issue. i initially started with the kiln it is firing to temp. We fire slow bisque and slow glaze programs to 06 and 6. I have tried bisquing to 04 with a hold on the end but the defect came back... I have tried a hold on the end of a glaze firing (20 minutes) with little improvement. We have tried the ware with this glaze in 3 different kilns all have the same problem especially on larger ware. We have also tried wiping down the ware lightly with a sponge on both sides did not help. I am thinking it must be the glaze. But I have no idea where to start. Help.

I am using a combination of glazes, Olive Green Celadon and Waterfall Brown, to get the effect I like on some of my work. Unfortunately I am running into a blistering issue more times than not which ruins the piece. Check out the image below. These are Cone 6 glazes and I have tried changing the temperature for the bisque firing as well as making changes to the glaze firing. The most recent changes to the glaze firing is to fire to Cone 6 then drop about 100 degrees (Farenheit) and hold the temperature for 30 minutes and then slow cool to 1,400 degrees. I have listed the recipes for the two glazes below for information purposes (approx 10,000 g batches). Glazes were sieved using a 100 mesh screen. If anyone has had a similar problem and come up with a solution I would appreciate hearing from you... Thanks. Olive Green Celadon Custer Feldspar 2000 Gerstely Borate 2000 Nepheline Syenite 2000 Silica 1500 Wollastonite 1000 Dolomite 200 EPK 500 Red Iron Oxide 200 Titanium Dioxide 100 Cobalt Carbonate 50 Copper Carbonate 300 Waterfall Brown Frit 3134 3350 Frit 3195 2600 OM4 Ball Clay 1700 Silica 2350 Red Iron Oxide 1250 Rutile 100