Rick Wise

Many thanks to you all. Potters are very generous with their time and expertise!

I have encountered a glaze recipe (below) I want to try that calls for "Frit 4124" but I cant find that available or any info on what it is or what may be a suitable sub. Any ideas? 31 Silica 17.6 Frit 4124 17.6 Whiting 13.4 Kaolin 10.4 Zircopax 10Total base recipe100 Copper Carbonate 2Total102

Doubt it as it is the same body I have been using for some time. Same clay, same glazes, same techniques other than more trimming of the upper walls.

After several years of successful cup making I have recently had a rash of cups that come out of the glaze firing (electric, cone 6) with invisible cracks in them. The cracks run generally top to bottom and are hard to see until you know they are there. But if you thump them the flat sound gives it away. Some are ok at first and crack only upon being filled with hot coffee for the first time. I'm looking for an explanation. My hypothesis is this: I have recently been trying to get more weight out of them at trimming. I start with 16 oz of clay and try to trim down to less than 1

When I first learned about terra sig I just fell in love with the look it produces on greenware. But then realized that the look disappears upon firing (Cone 6 stoneware). Is there a way to keep that satiny, shiny lustrous look but still fire it high enough to have functional ware?

Since asking this question I've been doing some experiments using (1) magic water (2) Spooze or (3) mix of clay, tissue paper, vinegar and water -- attaching handles to overly dry cups. I have to say that (3) appears to be a clear winner.

Just what I needed to know Pres -- thanks.

Pres -- you say you like and use Magic Water. I know the recipe, but not how its used. Am I correct that you use it along with plain slip? Or do you make the slip with the Magic water?

There is a lot of discussion in this thread regarding the best ways of joining clay -- some favor Magic Water, some favor . I find this perplexing since vinegar () is a flocculent, and sodium silicate (Magic Water) is a deflocculant. Right? How is it that both may work? In other words, what is the contribution of each (floc or defloc) to this process? It would seem logical that one or the other must be counterproductive. (I have heard the wonderful Phil Berneburg of Washington Street Studios question the utility of vinegar in this application) Full disclosure: I have been

Thanks Liambesaw!

Cracks are all the way thru cup not just in glaze. They leak.

Pics of the cups here:

I will try to post pic tomorrow. As to "poor glaze fit" I assume that means a poor matching of glaze with that particular clay? It was a clay/glaze combo that is my standard with a long history of success. But re the "unvitrified body" -- might that be from a firing that got interrupted by a power outage?

Puzzling new experience for me. Two cups -- both from the same firing -- I sold to a lady cracked upon first use -- when she poured hot liquid in them. Cracks were jaggedly vertical -- almost invisible but allowing leaks from the cups. They had appeared to be fine when they came out of the kiln -- perhaps thinner than most but I was pleased -- not worried -- about that fact. Anyone care to venture some ideas why this would happen? I'm now worried about others that may have failed -- or will fail --without my knowledge.