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That makes sense, lots of potters attached to old school ways of thinking. I recipe test for my career so my brain just doesn't have the capacity, needs a little cheating lol. It will be very interesting to see how the tests turn out. At the very least I'll share results so others will know!

I don’t know if this is still holding true with newer folks, but mason stains used to be considered “cheating.” Absurd purist ideas aside, sometimes they can give rather flat “candy coating” results if they’re not modified somehow, or used in an off label way. Off label usually meaning in a lower concentration or with less/no zircopax than usually recommended if you want them to give a more translucent result, or combining them with some rutile to give visual depth, etc. And of course, you’ve already encountered the varying base glaze requirements for making sure they turn out as intended. Glaze testing can get really pedantic and boring, and it’s easy to get turned away if you don’t see some kind of positive or interesting result on the first round or 2.

We have been using Advancers in the glaze kilns at the college for over 10 years. Costs were not an issue as we got grants. The main reason we liked them so much is they are nearly indestructible (if you treat them properly). With student glazing errors, drips pop off with a stiff putty knife and a few swipes with an old green grinding wheel held sideways cleaned up the rest. No more chiseling and grinding divots into the corderite shelves, no more kiln wash. When we bought new kilns at the community studio, I just told them to buy Advancers for the glaze kilns. Same problem with everybody trying to do the Amaco drippy layered look and causing puddles of glaze on the shelves. Maybe in your own private studio, you have better control over your glazing, and when you make a mistake, you learn from it (which the students and community users don't pay the price for their errors). In my personal studio, I do some crystalline glazes which, by definition, are runny. Sometimes the catcher pot breaks from the stress. Advancers to the rescue.

Ahh you were right, the recipe was set to private, all fixed! Thank you for the insight & link. Good to know about zircopax, I'll start with a low % stain and work my way up. I don't know if I'm looking the wrong way but I didn't see many mason stain glaze tests on glazy. Feels like I'm going in blind!

I've never had that problem, even with the really thick CoreLites, but I can totally see how it may be an issue.

There might be a little more to the calculation than you accounted for in just the economics. I have a mix of both corelite and advancers for both my large electric and my gas kilns. I had lots of issues with warped shelves and the corelite were much better. I was still getting a lot of warping in my slab plates with the core-lite shelves. The advancers completely fixed the warping. I don;t think it is only because they are very flat. I think they heat the ware a little more and allow slab plates to settle perfectly flat on the perfectly flat shelves. I use the advancers for slab plates and the core-lites for bowls and mugs. I recommend a mix of advancers and core-lites for a compromise in firing properties and economics.

I've done the math on the cost of Thermal-Lite and CoreLite shelves for my 28" wide kiln, and it will take almost 875 firings before I break even with the more expensive shelves, and that's with buying two sets of the CoreLite because they won't last as long. Because I would only save 1 7/8" of height per firing in a glaze firing with the thinner shelves, and half that in a bisque, it's like getting a free firing every 19 loads. That averages out to $1.11 savings per load, which isn't much. This is also assuming I never accidentally break any of the Thermal-Lite shelves, and that I actually fire the kiln 876 times over the life of the shelves. For me that's not a problem, but for the average hobbyist who does 2 firings a month, that means it'll take 36 years for the more expensive shelves to pay off. However, for a production potter the extra 2 inches of space means 5% fewer kiln loads, which can really add up if you're firing a lot. And if you have a larger kiln than a typical 27" tall electric kiln, like a large gas kiln, then the payoff will come much faster. As for the weight of the more expensive shelves being so much better, they're really not. The 26" half round Thermal-Lite and CoreLite I used in my calculations have a weight difference of only 1 pound, so it's really not enough to make a significant difference in wear and tear on your body or the cost of firing.

I just made my morning tea- porcelain mug with water in it, microwaved for 2 minutes. The water is too hot to drink, but the mug handle is very cool, like maybe 85 degrees instead of room temp. I'm going to call that microwave safe.

@davidh4976, I was thinking more about the 450F temp and crazing. Is the ASTM554 test still valid if the body cracks but the glaze doesn't?

Pinched your fingers yet? (yup, I've done that a few times )

My guess would be it's because of different reflected indexes between the glazed and unglazed surfaces while in the microwave.

A few Artista threads; there are at least three long time Forum regulars who own(ed) and use(d) an Artista: Artista Potter's Wheel Question - Equipment Use and Repair - Ceramic Arts Daily Community Speedball Artista Potters Wheel - Equipment Use and Repair - Ceramic Arts Daily Community Speedball Artista Pottery Wheel - Good Or Not ? - Studio Operations and Making Work - Ceramic Arts Daily Community

The chain won't short out a thermocouple connection permanently, it'll just make it read funny while it's touching. Double check your thermocouple connections at both the thermocouple end and the controller end. Make sure the +/- wires are in the correct positions. On type K thermocouples, yellow is positive, red it negative. Maker sure the thermocouple isn't too close to the metal casing on the kiln.

These pieces were all dry, right out of the cabinet.

For those that haven't seen it:

In reduction the oxygen in the iron oxide is removed leaving the pure form of iron FE. Ive done heavy reduction on pieces sprayed with straight iron oxide and come up with a silver gray finish.

Well, can you show the interior? Looks like a Min glazing technique.:-)))

Thanks for the input ! May go for the Shimpo v lite .

It is coincidence that @davidh4976 mentioned a clay body so high in iron that a magnet will stick to it and I received in the mail today the strongest magnets I’ve ever seen. So, of course I had to play.. My clay is a local iron rich earthenware that vitrifies at cone 03. Not all the pots do this, apparently only the ones that are reduced heavily and fired to maturity.

I question the testing using the same piece for each subsequent heat increment as each cycle will stress/shock the glaze. I know that's the point but I agree with Hansen's take on this. I sometimes go 300F/ice water, then 315F/ice water then 325F/ice water. If a glaze doesn't stress craze from this I don't think it will with everyday normal (sane) usage. 450F to ice water IMHO is far too extreme! We are after all making ceramics, not metal bakeware. It does seem logical to soak the test piece for 12 hours after a reasonable stress/shock testing though. edit: In the past I did try the boiling water / ice water testing, had a glaze that passed it so went ahead and glazed a load of pots with it which later went on to craze. I'm sticking with the oven/ice water test, greater difference in temp therefore a harsher test, either the one above or just 3 sets of samples at 315F.

Yes, @davidh4976, ASTM C554 is the “prerequisite” test for test C1607. And I agree, putting pots through the worst I can imagine a reasonable person doing in their kitchen gives sufficient information as to how they’ll hold up. I believe it’s important to use your own work, it helps you understand what you’re expecting of people.

You should talk to Orton about shorting out that connection

Hi and welcome! Stains are fun to work with, especially for us dark clay users. And the reference chart you’ve already found is a very good reference is this section of Digitalfire. Tony identifies the stain by number, which is a good practice as there are 3 different numbered stains with the name “dark red” and they all have slightly different chemistry.Tony’s got examples of the Canary Yellow and Turquoise in a magnesium matte glaze base, so you can see how those 2 respond, at least. Speaking of recipes: the second link you’ve shared comes back as a “does not exist” error. If this is a recipe on your own page, make sure it’s published so we can see it. Zircopax won’t make the colours pastel: glaze colour theory doesn’t work the same as paint. If anything, it’ll make it brighter and more saturated, because more of the colour is reflected back to your eyes.

Maybe you mean ASTM 554? It calls for three passes of going from 250F to room temperature water without crazing. Repeat at +25F increments up to 450F. Crazing fails the test. Too much work for me! I just rely on three passes of boiling water to ice water to determine whether it's going to craze or not. It is a little bit more of a cheat for me because boiling water at my altitude is only 199F. Although the microwave test calls for doing ASTM 554 first, to me, the two tests seem mostly independent. If you are going to determine whether a piece is microwave safe, microwaving it and seeing if it gets too hot seems to be enough for me.