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Min
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Posts posted by Min
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Are you in an area that has freezing temps during the winter and would the birdbath be left outdoors year round?
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Copying a design versus using the same technique while making a pot are two different things. Are there any new designs in functional ware that haven't been done before by someone somewhere, I don't know but I sort of doubt it.
I have noticed quite a few makers doing exactly what you describe; leaving the mark of the making process visible at the joins. I don't think you need to waste your energy trying to justify your work. Getting inspiration from others work is one way to challenge yourself into making new forms, and making them your own. I'm sorry you are going through this, it must have been upsetting to you.
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Is it only commercial glazes you are interested in? If you are firing lowfire you can still use a commercial raku glaze then stain the crazing with calligraphy ink (or china paints with a subsequent very low firing).
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56 minutes ago, Marilyn T said:
I recently purchased a box of M390 and threw some test bowls.
Tagging @Callie Beller Diesel on this in case I'm misremembering but I believe she fires 390 to cone 7 for absorption reasons.
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It seems like you are going through an inordinate amount of glaze testing to solve what really appears to be a clay problem. Have you tried contacting Laguna with the batch number and asking them if they have any thoughts on this?
Is using a different red clay an option? @Callie Beller Diesel uses Plainsman M390 very successfully, is this an option for you? Could you use the clay you bought for another purpose?
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Hi Kylie and welcome to the forum.
Thread linked below from 2022, same kiln but brand new and with furniture, bought for 550. For a manual kiln 950 seems a bit steep.
https://community.ceramicartsdaily.org/topic/28072-cress-electric-kiln-fx23-p/
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750 ml yogurt container, so I guess that would be nearly as small as the paint cups with the handle. It sits in the splash tray (Bailey wheel), don't keep any sponges or chamois in it. I start with warm water then top it up as the day goes along. After a few throwing days I put it to one side, stir a splash or two of peroxide and then it goes into the reclaim. 3 yogurt containers used in rotation.
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I think that since so many of us fire to midrange the go to mindset is bisque low, fire higher to glaze. Problem with this when working with earthenware is more often than not the commercial glazes are rated in the 06-04 range yet many earthenware bodies will actually mature higher than this and still be porous enough to take glaze well. I haven't used the body in question, but if it can go to 02 (as the lit suggests) then I would at least try 03 and see how it does.
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11 minutes ago, Babs said:
My point was, given Min's info on clay, at a bisque to C03, your clay would be not very porous do would not take up much glaze if dipped,
Approx 6.5% at cone 06. I would do a test firing to cone 03 and include some test tiles. Just like the kiln firing it’s going to take some testing to see how the glazing. I’m not a big fan of underfiring clay bodies. I couldn’t find any data on absorption figures for anything other than 06, would be something I would test.
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Hi Hannah and welcome to the forum.
I've never used ash from domestic waste but your post has made me curious. I did a quick google search and found a fair bit of info on Municipal solid waste ash. From one study the main components found in it were Si, Al, Fe, Mg, Ca, K, Na, Cl, SiO2, Al2O3, CaO, Fe2O3, Na2O, K2O. But also found in the fly ash were the heavy metals, "Cr, Cu, Hg, Ni, Cd, Zn and Pb are the most commonly found in MSWI ash, and Zn and Pb usually exist in the largest amounts (fly ash and bottom ash..."
For a comparison a general generic analysis of wood ash from Hamer and Hamer would be 8 Na2O, 17 K2O, 12 MgO, 27 CaO, 1 Al2O3, 24 SiO2, 7 P2O5, 4 Fe2O3
The heavy metals lead, cadmium and mercury found in domestic waste ash testing done in the link (below) I pulled this info from would be an area of concern.
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Small test kilns can fire incredibly fast, much faster than larger electric kilns. So yes, if the “real” pots will be fired in a larger kiln then you’ll want to approximate the same firing speed. I would suggest asking the studio where you fire your work what schedule they use plus how long the firing takes then program your test kiln to match it as close as you can. Test kilns also cool down super fast so you probably should do a slow cool down also. This wouldn’t be necessary for clear glazes though.
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I looked up the Mass Red clay from Sheffield Pottery, from their info it fires from 06 up to 02. I don't use commercial glazes so I also looked up the glazes you are using, Mayco Elements have a range from ^06 up to ^6 and the opalescent are ^05 if you go at 270F and hour for the final 200F of firing and the Artist's Choice recommend ^05.
All claybodies are strongest when fired to their top maturity temp/cone. So for your body the clay needs a higher bisque than what your glazes fire to. This is okay for earthenware as the body will still be porous enough to accept the glaze well. I would suggest bisque firing to ^02 and turning the dial up very slowly. Don't rush when you turn it up! Leave peeps open to get air through the kiln, it helps burn off impurities in the clay. I would suggest leaving all the peepholes open until you see the kiln glowing red inside then shut the bottom one and leave the top one open for the entire firing. Once the kiln stops then you can close the top one off. (I'm assuming it has 2 peepholes?)
For the glaze firing, again you want to slow it down, doesn't have to go as slow as the bisque though. I'm not familiar with your kiln but what you are trying to do is slow down the firing, Try and stretch out the middle and then particularly the end of the firing. Someone more familiar with your kiln than I am should be able to help you with this part.
Given that the clay has already reached it's maturity with the bisque firing then the glaze firing is to get the best looking glazes you can. Cone 05 should do it although the Mayco Elements can go higher, if you have a hotter area in your kiln you could try putting those glazes there. When I looked at some images of Mayco Elements I do see a fair number of pinholes in one of them when fired to ^06 so the odd one might be more prone to pinholes. (image below from Mayco's website of Oyster Shell)
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For sure you can get the chem to match using silica + calcium carb for wollastonite. I've done the reverse with recipes calling for calcium carb and subbed in wollastonite and reducing the silica in the recipe so the formulas match. What I found was the wollastonite versions melted noticeably more. Some recipes won't show a difference, depends on glaze mobility and how much CaO is involved. I think another factor is the mesh size of the silica being used in the recipes. Perhaps very fine silica, ie 90 micron compared to 45 micron would show a difference in the melt if used with calcium carb? I've always thought of wollastonite as being like a frit, albeit a lumpy one, it melts really well and with minimal LOI.
- Piedmont Pottery and Hulk
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Just to clarify you are firing lowfire glaze to cone 05 on a lowfire body that has been bisque fired to cone 04? Or cone 6 glazes on cone 05 and 04 bisque? How fast are you ramping up the kiln for both bisque and glaze? Is it possible to do a hold/soak with this kiln?
Are the glazes your recipes or commercial ones? If they are your recipes could you post a recipe or two that are giving you problems?
What claybody are you using?
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14 hours ago, LeeU said:
if I used Manganese Wash
Is this the commercial Amaco Wash you are using? If it is I would try brushing it on the wiping it back with a damp sponge to remain in the recesses then apply a glaze over top. I think leaving it without wiping it back would be too intense. Whatever glaze you use will dilute the intensity of the Amaco Wash.
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If it hasn't been fired on yet then yes it can be dusty.
It would just be a guess but the least expensive materials to use in a kiln/ batt wash would be kaolin and silica so if companies are trying to save money with the wash they supply they will load the wash up with that and skimp on alumina hydrate. There is a link below discussing kiln/batt wash with some tried and true recipes (it's towards the end of the link). Also, I would suggest wiping it back from the edge about 1 cm and wipe off any drips from the side of the shelf.
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@MsBeth, for the fondant molds are you using flexible silicone molds?
I think there is a bit of confusion with the terminology being used, when you say "clay castings" is seems like you are using casting slip. But then "press the clay into the mold" sounds like you are using pugged soft clay.
I have used flexible silicone molds and soft clay, I very lightly wiped the molds with veg oil then pressed the clay in then flexed the mold enough to have the clay pop out. There was a bit of distortion with the molds with undercuts but it was easily fixed since the clay was soft.
Dusting molds with cornstarch is also an option, don't have to be concerned with airborne silica with it.
Welcome to the forum.
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15 hours ago, nuna said:
Bisque super low at cone 020 or so. In this case, would it be safer to fire it fast or slow?
Slow. Both for firing up and cooling down.
These pictures are from Digitalfire of lowfire ware, pots have cracked from uneven cooling, edges will have cooled faster than the middle area of the pieces. The way to avoid this is to have the cooling down go as evenly as possible. Slow the cooling down between 1150F - 950F, I go at 100F/hour through this zone with suspect work.
There is negligible shrinkage, ie less than 1% between bone dry greenware and bisque firing to ^06- ^04, would be interesting to see data that shows refiring to a lower temp causes more shrinkage.
edit: when having your piece in the kiln put it between shelves, not at the top or bottom of the kiln, this helps the heat even out also. I put rectangular or triangular kiln posts around the outside edge of the shelf also. (round posts can roll)
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On 3/13/2024 at 9:59 AM, SSerrano said:
Thanks for your quick response!!! Any guess how much food coloring I should add? I have a tote of slip that's about 150 gallons.... maybe a pint or 2 should do the trick? Crazy question, I know.
If the food colouring is just to tint the raw slip then I would suggest using paste food colouring rather than the liquid, it goes much further.
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If all else fails MAGMA really should work to suspend iron spangles. I've noticed it can be listed as out of stock at Brackers quite often, if you decide to try it I would suggest emailing them and asking to let you know when it's back. It does thicken the glaze a fair bit and slows down the drying time so that needs to be taken into consideration.
https://www.brackers.com/magma-miracle-anti-gravity-multipurpose-additive/
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Hi and welcome to the forum.
Link to the Ceramics Arts Daily Tried and True Raku Glazes here if anyone uses any of these recipes.
Giving this thread a bump, hopefully someone will chime in.
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5 hours ago, Katie S said:
She expected that it needed to be fired to cone 10 for a bisque firing, which sounds wrong to me. I asked her to check the bag/brand and she was gifted it from an old friend and has no idea what the brand is.
If she isn’t absolutely 110% sure it’s a cone 10 clay then I would pass on this.
5 hours ago, Katie S said:She doesn't plan on doing a glaze firing.
This makes sense to fire the clay to maturity / cone 10 if she doesn’t plan on glazing it and it is indeed a cone 10 clay. She might want to leave it as bare clay or be planning on doing a cold finish on it. Firing to maturity would be a clearer way to describe what she wants rather than calling it a bisque firing. A mature body is far stronger than a bisque fired body.
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The concave then convex side design might also be contributing to it being pulled out of round.
Clay body for birdbath ?
in Studio Operations and Making Work
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I've seen a birdbath basin made a slab draped over a really large styrofoam wreath base. I haven't used either of the claybodies you mentioned but just by looking at the specs I would lean towards the Laguna WC611 given the porosity is lower. Whichever way you land up making it compress the heck out of it.