Babs
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Posts posted by Babs
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Friend used to use inner tubes from various tyres, cut knotted , tied and so firth!
Free
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Rutile may do this, titanium dioxide opacifier, if dirty rutile may perhaps "leave behind" its impurities as temp goes up?
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Hi, would you upload images and poss the glaze recipe then folk will be able to work out what's happening.
Fickle nickel can cause honeys to blue in some conditions.
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43 minutes ago, Bill Kielb said:
Do you fire with cones?
What cone are you firing to at present?
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3 hours ago, Chilly said:
You can scrape the rough side to make it smoother. You might need to use a rasp or fine cheese grater. Or even coarse sandpaper. Wear a mask and clean up properly afterwards. I do such things on a board across the dustbin in the garden, dust goes straight in the bin.
Give it a good wipe down with an old, damp sponge after and allow to dry.
I, like, @Hulk use one side for light clay, the other for terracotta.
Do you use anything to help release the plaster from tin?
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I have used it on unglazed bottom third of yunomi to get a toasty look, brushed on at bisqued stage. Be careful not to touch the washed area as the finish will be affected by this.
I have only brushed, so can't comment on any othrr methods.
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3 hours ago, MKG001 said:
Hm customer support added that this glaze seems to do better with a clear liner glaze inside the pot. Mysterious, but I'll try it.
Well inside a functional pot would be better for hygienic reasons and to get a stable glaze where lips and food touch, it won't do anything for your problematic glaze.
Could try dipping the pot in water prior to your first brush on, may alleviate the prob Dick mentioned re 1st coat applic. Or have a thinner pot of glaze for 1st coat so the surface gets fully coated.
Interesting that the producer says it's finicky.
Some filk drop temp after reaching goal temp. and soak to allow blemishes to heal over. Wouldn't help your elusive blue colour.
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Have you used this glaze before successfully?
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If firing it yourself, follow bisque ramp to 600°C then can adapt faster firing to top temp you require.
If in studio ,i.e. you not in control, a bisque to Cone 04 would be fine imo
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2 hours ago, Callie Beller Diesel said:
Adobe is great in the desert, but notsomuch where we get more freeze/thaw cycles. In college it was a fun intro first year project to make adobe sculptures in the courtyard as a group out of some reclaim and straw. They’d be left in place and by spring they’d be pretty disintegrated.
Can use a sealer end product and protect under wide verandahs...great lesson to learn re clay though, Callie.
Folk here @glazenerd added laterite rubble to the clay mix!
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As well, is it sitting on a suitable base? Distances from walls.
I placed my"station" right next to the kiln.
I fully explained the workings temps etc to classes, secondary.
I erected a "fence" and I had a safety chain so noone could open the lid. Putting on whIn students left school , then there in the wee hours to check the turn off., kiln sitter. Unpack a day later, packand so on. I inherited 30 firings of previous teachers pots, adult classes as well as students, whew.
Your kiln speci plates will say what cone it is capable of reaching.
Have a good time.
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Is your kiln toploading? Do you use test cones?. Top shelves of top loaders can be cooler.
Before altering everything, if have no cones, add a soak to top temperature, Try 10 mins to start with.
Refire a failed pot in next glaze firing, on a lower shelf.
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3 hours ago, Min said:
There are a lot of possibilities of what is causing it. I can't recall seeing this issue before. It's almost like an Egyptian paste where salts form on the surface but at a much larger and localized scale. Could be soluble salts precipitating to the surface or a firing issue. It looks like the problem is worse on the rims which would make sense.
We don't know the firing cone reached on the shelves with this problem versus those that fired okay so thats one variable, size of the kiln, how fast the problem ones cooled compared to ones that didn't. Was the shelf the problem ones on in a small or large kiln, shelf placement in the kiln? Is there a pattern with the firing and the results you can ascertain?
Glaze will be extremely high in R2O fluxes (sodium in particular) and very low in clay. This won't be a durable glaze insofar as being suitable for functional ware. Copper is extremely high also, again indicating this glaze won't be suitable for functional ware.
May I ask what the items are for? Non functional work? If you want to see how badly this glaze will leach out due to being a very unstable base with high amounts of copper put a slice of lime or lemon on it (cut side facing the glaze) then cover with plastic wrap for a couple days or submerge part of a piece in household vinegar for a couple days then rinse and dry it and see how the glaze has changed. Also, with such heavy crazing and I'm assuming a claybody with a high absorption rate this would also be a very poor choice of glaze for functional ware.
I have had a similar thing happen. I actually posted years ago.
I live coastally so the rainwater added to the sodium. I took the glaze higher and added a soak . Prob solved .
My glaze was a frit ,nephsy high C03 glaze,
Didn't craze .
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A cure used to be adding..Barium Carb to clay body if "proper" scumming. This one I'd be purting cones on shelves to get an idea of temp differences.
Refiring higher would sort this I think. What is your glaze recipe? What is the temp you're firing to?
Water supply?
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Think the scumming pots have been fired at a bit lower temp.
Can you wipe it iff and does it return?
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Hmm busquing lower will increasd the porosity and so pit will suck moisture out of glaze more rapidly. Wondering if spraying pot with starch or sugar soln will seal it enough to allow glaze to be painted on more effectively
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Ok, butyour clay will be very porous snd hinder the glaze spplicatin. Try dunking the piece in a bucket of water then glazing, can't harm It, let it dryif no good.
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You could try bisquing to cone 04. Your clay will then be less porous and your glaze will brush better, water wont be sucked into the pot, along with Min's advice.
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So ypu are using frit and nephsy and a little bentonite, and it is settling between brushes, i.e. you are constantly having to really mix your glaze and so the gum? From your original post.
Am I way off to suggest super saturated saturated magnesium sulphate, Epsom salts , to help suspension?
Or glycerine if "brushability" is the prob.
What temp do you bisque to?
What temp does your clay vitrify?
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So ypu are using frit and nephsy and a little bentonite, and it is settling between brushes, i.e. you are constantly having to really mix your glaze and so the gum? From your original post.
Am I way off to suggest super saturated solution of magnesium sulphate, Epsom salts , to help suspension? A few drops?
Maybe photos would help.
I'd be spritzing water on glaze between layers.
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Cooking, ie powder form is mixed with very hot water, syrup thickness and left overnight. It is usually much thicker in the a.m. and I thin again.
Raise firing temperature of high thermal expansion glaze
in Clay and Glaze Chemistry
Posted
CMC GUM do the same?