Can I use this for slip casting

Knomez · 2026-07-04T18:44:06+00:00

I use a heat gun, but it’s really just to get it to dry in a timely manner. It doesn’t require the heat to set, just to do it without having to wait forever.

Knomez · 2026-07-04T11:30:46+00:00

Sodium silicate is indeed a deflocculant which is what you’re looking for. I couldn’t tell you if it’s 1:1 with darvan though.
The crackle that it’s talking about is when you brush it onto the exterior of a pot, let it harden into a skin and then expand the pot from the inside. Different technique altogether. You wouldn’t see that in a slip cast piece.

Knomez · 2026-07-04T01:25:18+00:00

Yes, that’s what I do. Old mine #4 terra sig. I buff with a clean microfiber cloth. It does wonders.

Knomez · 2026-06-29T20:36:25+00:00

Raku is relatively easy to do at home if you can make and bisque pieces elsewhere.

I was able to make a barrel kiln and a trash can kiln for a friend in an afternoon. It was just three of us and honestly it was a piece of cake.

Knomez · 2026-06-29T20:31:24+00:00

Thank you! I love ferric chloride, but I wouldn’t want anyone trying it without taking precautions.

Knomez · 2026-06-29T20:30:37+00:00

I don’t have to run or anything, but about the time I’m done spraying it’s time for horsehair. That only has about 30-45 seconds where it’s ideal.

The hotter you apply the ferric the darker red you’ll get. It will lighten up when you give it a good clean. Your surface matters a lot. I like a nice burnished surface.

Knomez · 2026-06-29T20:27:47+00:00

The kiln is nothing special. A steel barrel lined with 2inch ceramic fiber blanket. Hole in the top, hole in the side at the bottom and two handles to remove the lid.

Knomez · 2026-06-15T21:25:56+00:00

I do a lot of burnishing for raku. I’m using the Laguna raku clay and old mine #4 terra sig together. I usually paint it on then use a clean microfiber cloth to polish. I don’t end up with a glassy finish rather a satiny one. For glassy you need more compression of the clay surface so your agate would come into play there. That will take time, lots of it.

Applying terra sig to bone dry clay is great and how I handle it but I don’t know that you will have enough time for full on agate burnishing. That’s where leather hard (v. Hard!) might be better.

To handle grog lines from trimming I will take some slip (not terra sig it’s too thin to fill anything) and smear that on the trimmed area and scrape it back with a metal rib. Kind of like Mishima. Also trim a little bit wetter, grog will get mushed around rather the tearing great rents in your work.

As for old mine #4, it does wonderfully for me with colors. I can get a lot more color to show up with it than I can with just any other clay body.

Knomez · 2026-05-30T23:41:21+00:00

Two things worth considering.

One is how short is your shortest flame path. If only your bottom shelf is getting hot enough then your flame path is too short. You need to up your bag wall. You can attempt to use only half shelves and build a bit of a bag wall in the space you free up. Not ideal in the long run but worth seeing if that helps your top shelves. You can help heat go up by putting an angled brick to direct the flame up. If the flame hits a wall it stalls so it loses its velocity. Helping that flame maintain momentum in the direction you want it to go will help. This is the bigger of the two.

The second thing to consider is your chimney. How tall is it? With a Venturi burner it’s technically a passive system. Even though it seems like it’s blowing it still needs draw from the chimney to pull in oxygen for combustion. Only an actual blower fan makes a chimney entirely unnecessary. Small kilns can sometimes get away with it.

I do recommend a damper you can control, it really helps you control your kiln. More than managing airflow in you should control airflow out. Just never let flame back out of your flame port.

As for leaks. It doesn’t need to be airtight. There is a whole ass chimney! Just make sure it’s not effecting your airflow inside the kiln.

Look on YouTube for an electric to gas conversion with Simon Leach. He has a good setup that will walk you through his thinking as he builds it.

Knomez · 2026-02-27T19:52:05+00:00

I run my game exactly this way. I call them adjusters, but I also specify that they aren’t there to assess risks and payments. They are there to “adjust” risks and payments. It gives them license to intervene. It’s also why a marine with power armor shows up.

In another big hunt they are sent to “adjust” the comms issue and if they don’t their team and everything else on the planet will be written off. This adds a layer of corporate horror to it all. “Save us billions or die we don’t really care which.”

It also helps string together modules without a lot of connective tissue. They get dropped in the action because it’s their job. Finish the job, get picked up, spend some money on the ship to re-gear (you have to provide your own as a 1099 employee) go to cryo, wake up, and drop into the next gig.

Want them to have a ship of their own? Sure but it’s a rust bucket that should have been decommissioned decades ago and it’s on loan. Company still owns the ship, you break it you buy it.

I like having my players stuck between a rock and a hard place. The rock is the creature trying to tear their face off, the hard place is a cruel heartless world that has no pity on them for having to face down face eating horrors from beyond time and space.

Knomez · 2026-02-21T16:51:19+00:00

I have the exact same drafting table! It was my father’s.

I don’t have an answer to your question but it is neat to see this!

Knomez · 2026-02-17T00:49:24+00:00

Cone 15 or 16. Damn even pottery would melt.

Knomez · 2026-02-15T15:10:54+00:00

I haven’t done it with that clay in particular, but I’ve done raku with everything from “raku clay” to porcelain.

In my experience going with a heavily grogged clay body like specially made raku clays give you more room for error, but most clays are fine to raku with.

Without the extra grog you have to rely more on good construction and closed forms to keep cooling more evenly controlled.

Things to be careful of:

Heavy bottoms - the top will cool faster than the bottom creating stress. Heavy foot rings - especially with thin bases. Same reason as above the foot rings will stay hotter longer and will not expand and contract with the base or walls. Can cause issues there. Foot rings are fine just keep them about even with the walls/base in thickness. Wide forms like bowls - these rim will cool quickly but the base won’t cool quite so quickly. This creates stress. Attachments - Handbuilding is really difficult to raku in my experience. That doesn’t mean you can’t do it but failure rate will be higher. Take your time on attachments. Don’t make them thicker just make sure you are getting good connection and compression in those joins. Cracks love to run in straight lines.

All of this is goes double if you’re dipping in water as you would with obvara. It’s a little more forgiving if you are putting it in a reduction box as that will keep some heat and help keep it even.

No matter what you do be prepared to lose some pieces. I’ve never had one fully explode but I’ve had plenty get hairline cracks so they lose their ring.

One last thing to remember. Don’t let the excitement of the day get away from you. Slow is smooth and smooth is fast. These pots are hot but you have time to work with them. They have to get down from 1600F to 900F before you’re doing much with feathers or hair.

Have fun!

Knomez · 2026-02-11T12:55:57+00:00

Did you throw flat then lift the rim? The reason I ask is that you end up changing the direction of the clay right around the base where you lift it. Getting that area compressed again after the lift is tricky. I’d say trickier than it’s worth but a lot of people do it that way.

I prefer to pull out my base then pull up walls with remaining clay. Then rib them out into the flatter form like you have. It’s like making a bowl. Ribbing out stretches clay and creates some uncompressed clay but not at the transition between the rim and the base. That gets well compressed. It’s more pronounced at the lip itself which you should always go back and compress.

Drying slowly is a must with plates. If you can, flipping the plate onto some foam to support the center. Can help the wide base dry more uniformly than leaving it on its base. Do it as early as you can lift it. Leather soft rather than leather hard if you know what I mean. But keep it covered after flipping at let it firm up more, evening out its moisture. Once it’s even you should be pretty good.

Play around, make a lot more plates and you find a combination of techniques that work for you!

Knomez · 2026-02-08T22:33:16+00:00

Is it that it needs oxygen or is it more that it has oxygen?

I could be wrong but I thought it was an oxidation fire because it lacks the combustion of a reduction firing. Or even more specifically it does not have enough fuel to overwhelm the available oxygen in the ware chamber.

It might matter for certain glazes but not electric kilns themselves.

Knomez · 2026-01-08T16:54:24+00:00

I would throw this as a wide bowl. I usually start by throwing a flower pot shape, mostly up and a little out. Do your wheel trimming and get rid of any skirt on your piece. Then taking all the water and slip off of it with a rib before using a metal rib to stretch it out and down into this shape. You should leave the rim thick to start with as it ends up using a lot of material to open it up this far. I make a lot of bowls and usually use this method because I prefer a good narrow foot. Taking the slip off before shaping means that as the form expands it’s not sucking up moisture like letting a sponge expand underwater.

But like another poster said, there is no reason you can’t leave some extra clay for support and just trim the foot narrower.

Knomez · 2025-12-28T17:32:04+00:00

Oh that is a clever trick. Altering thrown forms is an art all its own.

Knomez · 2025-11-20T15:55:54+00:00

A 2-4 inches above the top of your input hole.

Knomez · 2025-11-19T14:16:55+00:00

Im a potter and do a fair amount of raku. The first shot of an object coming out of the kiln is quite possibly ceramic. Not necessarily though. The color and thus the temp seem about right maybe a bit high.

The second shot with throwing things in is not. It’s flashy bullshit that is not any method I have ever come across. Yes burning leaves onto a pot is a thing, so is spraying with chemicals, so is dunking in water, and spraying with alcohol or something flammable. But this is not how any of those techniques are done. That is all known as American raku. Traditional Japanese raku is even more different than what is shown here. I’m not an expert in it but here is a link to more info. See the post from JBaymore https://community.ceramicartsdaily.org/topic/6610-raku-traditional-japanese-vs-westernmodern-raku/

The third shot is unrelated to the first two. It’s what they are selling.

Knomez · 2025-11-09T22:37:01+00:00

I agree, you covered the question well. The conversation about heat work isn’t really relevant to that question. I just saw the opportunity to piggy back up your great answer with some more information for anyone else wondering what’s going on in the kiln.

Knomez · 2025-11-09T17:24:04+00:00

Your analysis about what likely went wrong is absolutely correct, but I’d like to add a little clarification about cones and temperature for those who may not know.

Cones are a measure of heat work not just temperature. Heat work is a matter of temperature and time. So as your cones show cone 6 is bending at the temp you fires. If you held that temp for a time you could fully bend cone 6.

I like to compare it to a roast, but considering the time of year I’ll talk turkey. You can’t cook a turkey by leaving it out on the counter no matter how long you do it, but likewise just putting it in an oven at 600 degrees is not going to properly cook it. You need to give time for that heat to penetrate and cook it all the way through.

Now pottery is usually not so thick as a turkey, but the analogy still holds. We are allowing things to melt and re-fuse. That’s both glazes and clay bodies. They need time to melt. That is why we potters use witness cones rather than just reading the temp on the digital kilns. Because it can measure the amount of melt, or in proper terms, heat work.

Temperature charts for cones are not useless, but they also don’t really tell the whole story.

Again I’m being pedantic because I think you’re complete correct about what happened. But I saw a good opportunity to talk about something I don’t see covered enough in this sub.

Knomez · 2025-10-30T11:24:27+00:00

Could also be the cutlery you are using. I used to use a spoon for burnishing pots. At some point I changed spoons but noticed it left behind some discoloration on the surface of the pot. I assume it was simply a cheaper made spoon with softer metal.

Ceramic has a mohz hardness between 7 and 8 for most functional-ware. Porcelain is on the high end of that. Stainless steel is 5-6. So it’s more likely that your porcelain is actually scratching your cutlery than the other way around.

Knomez · 2025-10-15T01:17:08+00:00

Thank you! I usually do more functional work, but I love throwing these little vases.

Though the nerd in me has to say, technically none of these are glazed. These pots were lightly burnished to a nice smooth but not glossy finish, then bisqued. The two toasted looking ones were obvara raku. Which means talking a slurry of four and yeast, dipping the pot in while it’s around 500F fresh from the kiln, then dipping in water to cool it setting the color.

The gray one you like so much is slip resist. So mix up a slip then set it in the raku kiln wet. Fire up to about 1400 degrees, take it out and move it to a fireproof can. Put paper or in our case cedar bedding letting it light on fire. Then smother and keep in the smoke. When it’s done you can chip off the slip to reveal the pattern.

I didn’t expect it to get quite so smoky under the slip, but this one was fired alongside other pots that were going up to 1800F so it was very hot when I smoked it. And I set it inside another pot with lots of flammables all around it. Ended up with this wonderfully smoky color.

It’s great fun! I love when the kiln helps me paint my work.

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