naked raku

Slip Resist Naked Raku - Take Two!

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I also tried a two-stage slip resist naked raku again; I dipped burnished bisqueware with waxed bottoms into slip, let it dry until it began to crack, and then dipped it in clear glaze before firing. I first tried one- and two-step slip resist naked raku out in April 2024, with mostly very low-contrast results. This time, I had higher contrast results, but also let some the slip dry too long before doing the clear glaze dip, as some of it actually touched the clay surface in a number of areas on the larger oval bowl and a couple on the smaller bowl (both below). Though it wasn’t intended, if it’s widespread like it is on the oval bowl, I actually am visually into the result (much like I am into crazing/crawling, which are also considered glaze defects).

Here’s the little dish, which has the highest contrast I’ve produced in slip resist naked raku:

And here’s the larger oval bowl:

Slip Resist Naked Raku Ceramics

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This was my first time doing slip resist naked raku ceramics, and it was definitely a learning process for everyone at the workshop, with more experimentation still needed moving forward! I did a fair amount of research the night before the workshop, and I was really glad I did. When we arrived the plan was just to do a one-step slip resist, but I had discovered David Roberts’ ceramics and wanted to try his technique. That required a two-step process (step one: dip into the slip resist, then let dry and step two: dip in clear glaze), which I convinced Wanda to let me do as well.

We began with the one-step system, but it was producing very low-contrast results for everyone. Some of them are still very cool, but I really wanted some full value finishes! As we fired the first of the two-step pieces, we saw that it was garnering better results. We’d already gotten through the majority of the slip resist pottery by then, but we pivoted the last third entirely to the two-step process regardless of whether folks wanted to carve through it. You may recall my last two pieces didn’t get fully fired, so I left them with Dakota Potters to refire another day. I recently got them back and in my opinion they’re the best of the bunch!

I put ten ceramics through the slip resist process; three were one-step and seven were two-step pieces. Unfortunately, we did find the two-step pottery were more likely to suffer casualties in the kiln. One of my two-step ceramics shattered so fully that it was just trashed there. Another blew a chunk of its side out, but is otherwise actually pretty cool so I plan to use a rotary tool to sand down the jagged edge and keep it.

Below I’ll show my eight undamaged pieces! First, two views of my first David Roberts inspired dish wherein I carved through the two-step surface to leave black lines:

Next, one view each of a one-step vase and bowl:

The below orb was also a one-step piece, but I added wax resist to the rim before dipping into the slip resist. Despite its low contrast, I think the pure black rim, the high burnish, and the shape contribute to making this one of my favorite pieces from this workshop. Here are three different angles of it:

Next, we have one image of the largest piece I fired at this workshop, and two views of another attempt at carving through the two-step surface on a small tray.

Here is the first of the two pieces I left behind to get refired - a large two-step orb!

And finally, the second of those two, an oblong vase:

Overall, I’m quite happy with these results so far, though I’d like to figure out how to regularly preserve larger white areas for even higher contrast. My burnishing was more successful on some pieces than others, but I do think it was worth the effort and I plan to continue to burnish for naked raku ware.

Obvara Orbs & Bowl

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I only fired four pieces with the obvara process this go-round, as I had run through a lot last time and I mostly wanted to learn the slip resist methods at this workshop. However, I wanted some obvara burnished pottery to compare to my previous unburnished works, and I’ve also decided my spherical handbuilt pots are a somewhat signature decorative form and so I wanted to have some obvara orbs. I did a smallish bowl as well.

The burnish was a mixed success with obvara - it delaminated in a few spots on two of the orbs during the dunking, which to my eye is kind of unsightly as the revealed clay layer beneath is bright white, so I color-matched and painted those in with acrylic. However, one orb and the bowl had no delamination accidents, and the resultant sheen on all four pieces is beautiful. Overall, I am happy with these and would be willing to burnish for obvara again.

Below are one photo of each of my three new obvara orbs and three photos of my new obvara bowl from my April 2024 Dakota Potters Supply workshop!


Obvara and Slip Resist Naked Raku Workshop

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I just got back from another raku workshop at Dakota Potters Supply in Sioux Falls, SD! I brought along a group of faculty, alumnae, and students from Morningside University.

This workshop specifically focused on obvara and slip resist naked raku. I really like obvara, but since I just did a bunch in the fall, I only put four pieces through the obvara process and ran ten through two slip resist processes: one-step and two-step slip resist. Dakota Potters Supply had tried to troubleshoot the slip resist one-step process in advance of our workshop, but they really hadn’t figured it out so we were all experimenting and troubleshooting with our the slip resist attempts throughout the day.

I still need to edit the photos of my pieces - plus, two of them were underfired enough that Dakota Potters Supply kept them back to refire again later, so I don’t know when those might rejoin me (if they stay whole)!

Here are photos from the day of the workshop (Saturday, April 20, 2024):

A New Challenge: Burnishing!

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I’ve been preparing for a special raku workshop I’ll be taking faculty, alumni, and students to in late April where we’ll be doing slip resist naked raku as well as obvara again. The slip resist naked raku in particular is a new challenge that is pushing me to explore outside of my comfort zone and develop my skills, as we’ve been advised that we should use terra sigillata and burnish these pieces for the best finish.

What is burnishing? Simply put, it’s when you polish the surface of the clay to a high shine. Why burnish? It is a luminous way to finish the surface of a low-fire piece of pottery that will not be receiving any glazing, spray acrylic coatings, or other surface alterations like wax or paint.

I’ve dipped my toe into burnishing before, as I tend to make very smooth pieces and have casually burnished parts of a piece while smoothing. However, I’d never really looked into burnishing before or set out to fully burnish a piece and keep its burnish post-firing.

After researching, I believe there are six main variables. Those are:

  • clay body

  • clay body wetness level

  • lubricant

  • polisher(s)

  • bisque temperature / cone

  • final firing’s temperature / cone

I also learned that any piece I’d partially burnished before automatically lost its shine during the quartz inversion and vitrification stages in a high fire, and that it’s also a waste to do with pottery that you’ll end up glazing as the glaze will take the place of the burnished surface. Good to know! Burnishing is really for low-fire, “naked” processes. (You might think to yourself that I have done some of those processes before, including obvara and saggar-fired raku. And I have! So I now want to try using burnished ceramics for those, too!)

My clay body is Chad’s Bod, which I believe is a new local mix that’s proven to handle the thermal shock of raku well but means I don’t think anyone’s published any information on how it handles burnishing. I was advised by the workshop coordinators to apply the terra sigillata to leatherhard pottery and then burnish with pantyhose, a soft cloth, or a plastic bag. I gave that a try, but then gave up quickly on the cloth/plastic bag approach and moved back to my tried and true agate tools. The terra sig began to sort of start to mix into the clay body, but I did get a very nice shine! However, once bone dry, all of those pieces lost their luster. I spent some time digging online and found out that’s to be expected, as at a microscopic level the clay surface wrinkles enough to disrupt that reflectiveness as it fully dries out. I reapplied another layer of terra sig and reburnished a couple of these pieces, but the terra sigillata began to delaminate / flake off. Upon googling, that’s also a frequent problem with this specific sequence (burnished leatherhard pottery with a terra sig layer atop when bone dry and reburnishing). I tried another lubricant I read about online, vegetable oil, for the second burnish of a couple more of these pieces in the hopes that it’d be less likely to flake off, and it seemed to reduce the delamination a bit but there were still hot spots. So my first four pieces have some minor surface irregularities.

Next, I decided to try the advice I saw online to apply the terra sig to bone dry ceramics. I did so, and that did seem to be a better solution. The terra sig seems less likely to delaminate. On one of those, I tried putting the terra sig on and letting it fully dry, then using vegetable oil to burnish; that worked out pretty well. Then I tried putting the terra sig on and burnishing it once it was mostly soaked in, and that also worked out pretty well. Since the latter is the faster method, that’s what I plan to do moving forward.

Once I troubleshot and mostly resolved the delamination / flaking issue, I refocused on getting a perfect burnish. In my mind, Magdalene Odundo’s ouevre is my gold standard for burnishing. Her handbuilt pieces have such a flawless burnish and high shine. My best pieces thus far still have some ridges and low spots… but I’m also just starting my burnishing journey!

I’ve come to believe that to get that clean a result, the piece itself needs to be flawless pre-terra-sigillata and then I need to try to ensure a perfectly even terra sig application. Easier said than done, but now that’s the next step I’ve been working on.

Amongst all of this, I was worried as I’d read that some beautifully burnished pieces lose their burnish in the bisque fire due to the quartz inversion stage and my friend Susan also witnessed that firsthand. My studio typically bisque fires to cone 08, and that’s not too far from the cone 06 to 04 temperature of our normal raku firing. I decided to risk putting my first five burnished pieces into a cone 08 bisque kiln load to see what would happen, as if they lost it there, it’s very likely they’d lose it in the raku too. I am very, very pleased to report that they kept their luster! This also means I am quite hopeful that they will be able to keep it through the raku firing processes as well.

Whew, this is getting long! I’m writing all this out for a couple of reasons. The first is that as much as I can find it frustrating at times, I deeply enjoy creative problem-solving and wanted to share a taste of such an experience with you. The second is that after spending a lot of time researching burnishing online, there are a lot of vague or contradictory pieces of advice out there. I want to provide a resource that explicitly spells out every variable I’ve used and tried so that future burnishers can easily compare notes.

So - below are my current, best burnishing techniques and I will update this post with any new insights as they come:

  • clay body: Chad’s Bod clay body, smoothed as perfectly as possible (but not burnished) during the forming and leatherhard clay stages using wooden ribs and plastic spreader; try to have a completely flush surface with no bumps, pits, or scratches

  • clay body wetness level: wait for the clay body to become bone dry

  • lubricant: apply terra sigillata as the lubricant because it performs well and it is whiter than the clay body which will increase the contrast of the final product; apply it carefully with a fan brush to both the interior and exterior of the piece and try not to leave any visible brush marks; brush it on continuously until you’ve put two to three layers onto the main decorative areas, and at least one onto hard-to-access interiors

  • polishers: after you’re finished applying the terra sigillata (when it’s not so wet as to come off on your fingers, but the bone dry pottery sucks all the moisture out very quickly so I do it pretty much immediately upon finishing application), use a combination of the plastic spreader, agate tools, needle tool, and river stone to polish, not pressing very hard and trying to go in multiple directions to catch any imperfect lower spots

  • bisque fire at cone 08

  • raku fire at cone 06 to 04 (fingers crossed!)

On the left, an unburnished Chad’s Bod bisqueware vessel. On the right, a terra sigillata burnished bisqueware piece (on this piece, I did not apply terra sigillata nor burnished the interior). Note the difference in sheen and color.