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Min
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Posts posted by Min
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Xiem BatMate is used for different purposes than the neoprene disc. My neoprene disc is about 3 mm thick. I use a Xiem BatMate (or a knockoff of it) to hold batts to the wheelhead without using batt pins but not to trim on. I know a lot of people use the Xiem BatMate to stop wobble in uneven batts with the use of pins but it works super well with plaster batts of any size and wood batts up to about 10" without pins at all. I use the neoprene only for trimming. Still have to keep a slight pressure on the top of smaller pots like mugs, no need for clay wodges to hold the pot down.
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Rutile is one of those materials that can make or break a glaze, it can vary a lot from batch to batch. I would try it out with a small test batch before using it in a large bucket of glaze. Colour difference might just be your new batch hasn't been calcined.
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@Morgan, have you tried slaking some of your dry scrap and seeing if it actually needs additional plasticizer? If you have been diligent in saving your slops you might not need anything. Re which one to use if you do need one, Bentone MA is what used to be called Macaloid. I have used that and also Veegum (it's not a gum either, it is a water washed white smectite clay, extremely fine particle size also).
If you do need to add some plasticizer I would weigh out a KG of dry scrap and then try just 0.50 - 0.75% of either Bentone MA (Macaloid) or Veegum. If you try the Veegum be careful which Veegum you get as there other forms of Veegum available, you want either Veegum or Veegum T. Whichever you use it has to be thoroughly mixed with hot water before adding to your slaked clay. I add the Bentone MA (or Veegum) to the water then whiz it with a handheld stick blender for about 20 minutes. It will go thick and very smooth, might need to add more water if it gels up too much. Once you have the dry clay slaked down add the Bentone MA or Veegum mixture to the clay slurry and continue mixing it until it's all blended. When trying out grolleg bodies I used 3% Veegum, it made a very plastic claybody that was quite sticky, I probably could have cut that amount back.
Hansen has the analysis for Bentone MA (aka Macaloid) containing MgO (approx 23%). Article on it here and on Veegum from Vanderbuilt minerals here. Either one will get the job done.
- Hulk and Kelly in AK
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Lot of good information here @neilestrick, good of you to address all the points in such detail!
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This thread is bounced off this one that was discussing extruders then went off on a bit of a tangent. I brought up the subject of thrown handles as another alternative for @Pyewackette . (other options such as cast, press molded etc in the linked thread also)
Super quick demo photos below, hope this helps Pye.
Throw a donut on a batt, for mug handles that need to be straight use as big a batt as you have or throw on the wheelhead if it's wider than your batts. Center the clay then open it up right down to the batt. While throwing the donut press down firmly on the clay as you are pulling it outwards from center.
Clean up the edges of the donut and shape into a dome top, flat, ridged, whatever profile you need. Can use rib made from an old credit/gift card to make identical profiles for the donuts if making a lot of one style that need to be the same.
Cut into the donut with a pintool then slowly rotate the wheel to cut the donut off.
At this point you can either let the donut set up a bit or work it now. Cut off a section and either hold it up and smooth the cut edge or let the sections dry a little then lay them facedown and smooth the cut edge.
For mug handles pull them straight and let them hang until they are dry enough to attach.
- Kelly in AK, Hulk, Roberta12 and 6 others
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10 hours ago, Pyewackette said:
@Min I forgot and just typed @Min in my last post above. I don't know why but the site software won't insert the proper notification code if you just type it. You have to select it from the drop down. So yes, I would appreciate illustration of your handle-throwing-shaping technique. Sorry!
Done, will start a new thread with it in Studio Operations and Making Work.
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Have you tried adding blunged bentonite to the original recipe? What is the goal here, soft slab building for functional wares?
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Faceplate shows it’s a 3 phase kiln, are you set up to run that?
- Bill Kielb, timheron and Pres
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@Pyewackette, is it just for handles (for now at least) you are thinking of building an extruder? I used to throw handles from a large flat donut of clay on a batt for baking dishes. Can put any number of ridges or gullies into them and make them however thick you want. After wiring the donut off I would let the clay set up slightly then cut off sections and gently pull them to straighten the curve out. (If this doesn't make sense I can do a quick one and post an image if you like)
- Rae Reich and Pyewackette
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I don't make tiles but I have owned both a front loader and several top loading kilns. My front loader had a floor element plus elements on all four walls of the kiln, coolest part of the kiln was the upper area. Don't recall having cool spots near the door. Hinges on the door were adjustable, door sealed well. Depending on the size of the front loader it might be more difficult to get it through doorways to your kiln area. How tall you are makes a difference too, I needed a platform in front of the front loading kiln to get the top shelf in without really overextending.
Richard Zakin (kiln building book author) and Frederick Bartolovic article below with some of the things to look for with both front and top loading kilns.
- Hulk and cmeiselman
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Might not be worth the work and extra time it takes to glaze mature clay, especially if your only option is to dip it. If you can, decant some of the water from the buckets so it's a bit thicker, that will help, as will warming the pots up to about 200F then dip. If not the just put the pots aside and move on, I know that can be easier said than done.
- Babs, Rae Reich and Kelly in AK
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@Pyewackette, not trying to hijack this thread but there is also the electric caulking gun extruder option too. I came up with the idea and Pres made it work. We collaborated on an article for it, link from Pres' website to it here. https://picworkspottery.blogspot.com/
- Pres, Pyewackette and Rae Reich
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22 hours ago, Pyewackette said:
What do you think of a manganese speckled clay like Peppered Creole in soda firing? I don't have that clay yet but I hope to have it very soon, maybe as soon as this afternoon if the shipment arrived as expected.
Nope. Bodies containing manganese shouldn't be fired over ^5 maybe a cool ^6. If you want that speckled look then find a ^10 body with iron particles for the ^10 soda firing.
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Whiz it in a blender. Either dry then wait for the dust to settle before opening the blender or with some water then pour it out and add a bit more water to get the residuals.
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Adding 20 SiO2 only brings the SiO2:Al2O3 ratio up to 6.1:1 (using Insight data) so I'm not surprised it isn't very glossy but it does look like it's moved it a bit towards a gloss. There is going to be a limit to the amount of SiO2 the fluxes can incorporate before running into the issues of undissolved silica itself causing matting.
Re the quote from Hansen above, is he talking low fire when he says "At lower temperatures the matting mechanism of MgO is that it simply stiffens and opacifies the glaze due to its refractory nature."?
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1 hour ago, BobMagnuson said:
If MgO is just a matting agent, I thought, how can adding silica reverse that effect? I don't know, but it did.
MgO is in the role of a flux, glaze in question is a high alumina matte, adding silica doesn't negate the fluxing of the MgO it moves the SiO:Al2O3 ratio enough to move from a matte to a gloss due to the increase of SiO.
edit: was the kiln slow cooled?
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@Pyewackette, +1 for just using a very light spraying of flashing slip.
Also, I would pour the liner glaze not spray it. When you spray inside a form such as a deep bowl or vessel there is a huge amount of glaze blowback coming back out at you. I'ld spritz the inside of the (bisqued) pot with water at the bottom and lower part of the wall where the glaze will be thicker and do a quick pour of glaze of about 1/3 the volume of the pot then very quickly pick it up and swirl and dump the glaze out to coat the inside. If you are using the same glaze for part of the top / outside then quickly dip that area after doing the liner.
I'ld also hold this pot back from your first soda firing. I would suggest taking some less precious pots, take some really good notes on what slips are on each pot, application details, where they are in the kiln etc. Learn as much as you can from the first firing, how other peoples pots turned out and any details you can get about those pots and the firing then apply that knowledge to the slips/glazes/placement/firing of this large one.
- Pyewackette, Kelly in AK, Roberta12 and 2 others
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On 11/1/2023 at 8:10 PM, BobMagnuson said:
I made up a batch of Bill Kielb's "Marcia's Matte", (See Oct 2) and added 10 and 20% of SiO2.
Did you do this with and without the MgO or was it just to demo the SiO:Al2O3 ratio effect on gloss levels?
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20 hours ago, Dick White said:
That's awesome for those in Canada. Will this be available in the rest of the world?
I have no idea, if anyone knows could they post?
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I'm not going to comment on the durability of this glaze but I did rework it to contain nearly double the epk and got rid of the nepsy and supplied what it did with a frit plus Minspar. Should suspend a lot better with less bentonite needed (if any at all). If you try it Morgan please just test a small amount first, what looks good on paper and all that.
edit: if you test this and find it's too fluid (because of the frit plus tiny bit of boron) then it might need an extra 1 or 2% of EPK
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A well fitting liner glaze is usually always used inside soda, salt and wood firings for all functional pots. Wouldn't want to drink out of mug without a glaze inside it. If the liner glaze has a significant fit difference from what lands up on the outside of the pot then the pot can dunt / crack.
If you glaze the entire pot and then it's hit with the soda it can very well cause excessive running of the glaze due to the extra fluxing of the sodium. If you just glaze the top of the pot and leave a lot of room for it to run it should be fine. It depends on how much soda the pot is hit with.
Nope, flashing slips don't all look the same. I used a few on the vase below. The lighter orange one has titanium in it, the red doesn't.
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Yay!
Filmed in Vancouver BC. Looks like it airs in Feb 2024
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1 hour ago, Roberta12 said:
I priced the extension legs for a Brent and they are OUTRAGEOUS in $$. I will find some cinderblocks and start there.
If you do want to give standing while throwing a go a less expensive way to go than the Brent extension legs is to use legs from an old table. My mum's old sewing table had solid wood legs, I repurposed them to be my wheel extension legs. (I use a Bailey which has the pipe legs like the Brent) If you can find an old table with solid legs at a thrift store or wherever that fit inside the pipe legs then remove them from the table, figure out the height you want then drill a hole through both leg and wheel leg and bolt them together. Since my Bailey is like Brent wheels and there isn't room to sit the foot pedal next to the wheel and use a hand to control it we added a piece of redi-rod to the side of the foot pedal then screwed a knob on top.
- Roberta12, Kelly in AK, Pres and 1 other
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Throwing out a thought that might simplify this debate.
Q: what colour response does cobalt give in a high magnesium glaze? (including midrange)
A: shades of purple
If the magnesium wasn't entering the melt as a flux then no purple.
Dave Finkelnburg article on cobalt purples and magnesium.
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cement board bat
in Studio Operations and Making Work
Posted
I don't think it is. Whatever works.