raku firing technique

My Obvara Raku Plates and Platters

in

In my previous post, I shared the obvara raku bowls I made on my October 21, 2023 workshop at Dakota Potters Supply. I also made some plates and platters! As always, you can click on any of the photos below to see them larger.

This first burnished plate depicts a bear, and you can’t convince me otherwise.

This next burnished plate is smaller than the first - it’d be good to hold jewelry or other small items.

A small obvara raku plate by artist Shelby Prindaville.

This final piece is the largest - it’s a platter or tray, and it has some light texture on its inside surface.

An Obvara Raku Workshop!

in , ,

After asking about it repeatedly for three years, I successfully convinced the lovely folks over at Dakota Potters Supply to allow us to do an obvara raku workshop on October 21, 2023! Obvara is a low-fire scalding-and-sealing process wherein you create a fermented sourdough/beer bath, plunge approximately 980°C naked ceramics fresh out of the kiln into it, wait for them to start to bloom with different tan-to-brown markings, and then arrest the surface carbonization process by rinsing the pieces off in a water bath. Obvara has an even higher chance of cracking due to the extreme thermal shocks involved than non-bath raku processes.

Getting the chance to do raku is relatively rare, and many ceramists haven’t even heard of obvara, let alone had the opportunity to do it - so I’m really grateful for the experience! Joining me on the trip were Morningside faculty Paul Adamson, alumni Calissa Hanson and Deb Murakami, and students Laura Greene, Taylor Greene, and Lauren Hedlund.

In addition, I learned about honey raku from a ceramist at this year’s ArtSplash festival - it’s basically like horsehair, feather, or sugar raku surface carbonization, but with honey! I brought some along and we tried it out too - though I want to experiment with it some more at future workshops as I was so excited about the obvara opportunity that I only kept one textured plate aside for honey raku.

Here are some photos from the workshop itself, soon to be followed by pictures of my finished pieces! I applied for and was granted funding from our Faculty Development Committee to help with my costs, so I made and brought 18 pieces along this go-round - both to make up for any thermal shock victims, and because I didn’t need to apply glaze to my obvara or honey raku ceramics so I could get more processed compared to when I need to apply 1-8 layers of glaze to each piece on-site before firing (for crackle and copper glazes or ferric chloride dips). If you’ve been following my raku workshop production, 18 is about double the number of ceramics I typically aim to bring.

My Favorite Ceramic I've Made Yet: My Last April 2023 Raku Saggar Piece

in ,

I have a lot of my own ceramic pieces that I love, and there are a number of those that I plan to keep for myself for the foreseeable future! I’m pleased with each of the ceramics that came out of my recent April 2023 raku workshop; that work spans the realm between good to fantastic. One piece I made is my favorite ceramic I’ve made yet, though, which is a hurdle that was relatively easy to pass when I was a beginner back in early 2020, but is now a much rarer event.

This piece, like the others in this series I’ve made, was dipped in three coats of ferric chloride, wrapped in Muehlenbeckia axillaris or Creeping Wire Vine and then aluminum foil, and saggar-fired in a raku kiln. It is finished with kitchen wax.

Ceramic glazing in general is a lottery; there are a lot of variables and some are outside of your control. I think I won that lottery with this vessel!

April 2023 Raku Crackle and Saggar Ceramics

in ,

This is my second post reviewing my April 2023 raku workshop ceramics! This one will cover two of my three “baked potato” aluminum foil saggar-fired ceramics and my clear crackle piece.

Based on my experimentation using plants at my April 2022 raku workshop, I only had real luck with saggar firing Muehlenbeckia axillaris, colloquially known as Creeping Wire Vine. I therefore used it again! Below is a plate that was dipped in three coats of ferric chloride and then wrapped in the vine and then aluminum foil and fired. The Muehlenbeckia axillaris impact is relatively subtle because it mostly went white to medium gray, but the plate overall turned out well. The very first time I did this “baked potato” technique, I used a matte clear acrylic spray. The second time, I went with gloss. I didn’t really love either, so this time, I went with applying a kitchen wax. I really like the way the wax looks, so I think that’ll be the winner moving forward!

Next, I did the same process with a vase - on this piece, I also sprinkled just a little sugar on as well for some small-scale spotting in the design. This one’s interesting as the Muehlenbeckia axillaris is more apparent, and it produced the full value spectrum on the same vase; the top vine piece is white to light grey, while the bottom vine carbonized a lot more and turned medium grey to black.

And finally, I chose to do a clear crackle on a small, necked vase. Handbuilding necked vessels is tricky, and I complicated matters with this piece by leaving my building process evident on the outside to contribute texture (while smoothing it for structure and stability on the inside). This was quite risky; I knew there was a good chance this piece could crack or break with thermal shock due to the thinner seamed areas. However, I was fortunate - it made it through the firing completely unscathed! I wanted to enhance the seams and stress spots that I had intentionally retained, so I painted over each of them and the lip of the vase with wax before glazing with Clear Crackle on the exterior. As I’ve explained before, this means the glaze doesn’t stick to the waxed areas, and the wax burns off in the kiln. The exposed, unglazed clay body then carbon traps the smoke in the post-kiln reduction atmosphere, turning a dark, smoky grey. I finished the piece by putting kitchen wax on the unglazed areas.

Again, none of the “cracks” in the below piece are structural - they are all decorative and this vase is fully sound.

April 2023 Raku Copper-Glazed Ceramics

in

I’m going to do a few different posts about my April 2023 raku workshop pieces because there’s a lot of good work to share. In this first one, I will review my copper-glazed pieces!

Below is a platter, which has some texture on its surface; I imprinted an equine femur into the clay body thanks to bones I was allowed to keep using from the LSU SVM anatomy lab. I first glazed it with White Crackle, then wiped the white crackle back down so that it stayed in the impressions, and also applied it to the rim. Then I glazed over the top with Copper Sand. I thought this would impact the coloration, but the white crackle (at least at that thickness) only really affected the sheen; where it was applied the glaze is glossy rather than matte. Though it’s not precisely what I envisioned, it’s a strong piece.

Next, we have a small, leaning vase. I chose to apply wax to the rim and throat. Then I glazed the exterior with Copper Sand, keeping in mind that the glaze doesn’t stick to the waxed areas. In the kiln the wax then burns off, allowing the unglazed clay body to carbon trap the smoke from the reduction afterwards. I was planning on staining the raw clay, but I ended up holding off as the variably smoky surface is interesting in its own right. I need to actually decide, as I will want to wax the raw surface if I don’t stain it.

This is probably the biggest of my raku pieces this go-round. This vase vessel has Litho Carb on the inside and Copper Sands on the outside. (I really like Copper Sand as it’s pretty predictable in its behavior for me, which is a rarity when doing raku.) The interior lip has an abalone-like appearance!

Next, we have my “golden bowl.” This piece is glazed with Dakota Potter’s new Peacock on the interior, and once again uses Copper Sand on the exterior. One of my students kept hovering her hands above it and singing reverential “aaah” noises!

And below is my final copper raku piece of the workshop! This one is an oddball shape; I wanted to push myself to make some handbuilt, necked vessels and in doing so created this flora-inspired vessel. I glazed it with Litho Carb on the inside and Midnight Luster on the outside.

My April 2022 Raku Ceramics

in , ,

I just completed another raku workshop this past weekend, and as I was looking through my files I realized I’ve not yet published the raku pieces I made at my last one in April 2022. Clearly I should do that before sharing my latest workshop photos and products!

On my April 2022 raku workshop, I wanted to try to carbonize various plant fronds or leaves onto the surface of my pieces. This was a complete experiment, and it was mostly a failure. I tried a variety of ferns and tropicals out, and one after another, they burned away without leaving a trace. Here are some plates that I attempted to salvage after that didn’t work out. With the first, I pivoted to a sugar and horsehair application. With the second, I tried to use ferric chloride to stain the surface with plant leaves that weren’t carbonizing, but they just left those not-terribly-appealing ferric chloride splotches.

Once I realized those techniques were not working, I tried etching fern fronds onto a plate in a “baked potato” aluminum foil saggar firing; it kind of worked, but I think it’s underwhelming. Since none of those plant techniques were doing super well, I just put a litho carb copper glaze onto my final plate.

I also made a rounded crackle vessel and the glaze turned out really well, but the ceramic physically cracked due to thermal shock so it’s got that permanent asterisk associated with it.

I glazed this spherical vessel with copper glazes (Copper Sand is on the exterior and I think that’s Midnight Luster on the interior), and it came out looking like a little planet! This one’s a definite favorite.

And finally, the one plant piece that turned out beautifully and justified all the failures: this is another “baked potato” saggar firing, and the Muehlenbeckia axillaris vines I used carbonized perfectly into this vase’s surface.

I also lost a large platter-like vessel (it broke into quite a few pieces and was not salvageable) and had another plate fuse with a kiln brick and lose part of its bottom. I eventually recycled that broken platter-like piece in my rock tumbler!

More Raku!

in

You got a sneak peek at some of my recent raku work in my exhibition shots from Functional Aesthetic, but here is the full reveal!

Above are three photos of one “baked potato” bowl. I used my own hair again as well as sugar for the carbonized marks on this piece.

This vase is very difficult to photograph well; it’s currently on exhibit, but once it comes back I’m going to see if I can capture it a bit better digitally. A couple of my friends who viewed the show said this was their favorite piece of mine. The way the glaze dots turned out reminds me of inset abalone shell.

This piece certainly didn’t turn out as planned; I experimented with a turquoise crackle glaze, but I really did not like the way the color came out, so we went ahead and re-fired it. I much prefer this hammered copper look!

This above bowl is decently large, and I chose to do the outside in a relatively matte glaze while the inside is a high gloss. It gives me dragon egg vibes. The Functional Aesthetic curator placed this piece in the choicest display spot, and I learned today that it was sold! I did see a viewer admiring it and gesturing to and around it at the reception, so I wonder if she’ll be providing its new home or if a different patron snapped it up.

This above vessel is kind of football-shaped, and its surface reminds me of a somewhat aged/stained city map. It has my own hair and sugar burned into the white crackle surface. I am quite into this piece.

I was really excited about how this piece turned out, as it’s adding into the “broken egg” series of clear crackle pieces I’m developing. The shape is hard to convey in photo, but it leans in a way that feels quite anthropomorphic - at least to me!

This bowl was intended to be another in the “broken egg” series, but it cracked coming out of the kiln due to the thermal shock and my thin walls. That’s more literal than I’d like for the “broken eggs” to be. It is still in one piece, but even after I epoxy over the crack (which I plan to do to bolster its structural integrity), it will have that weakness as it’s a fairly sizeable crack. I’m not sure if given the severity of the crack if I’ll want to display this piece, but if I do I plan to list it as NFS (not for sale).

And here is yet another casualty; however, this football-shaped vessel’s crack is more minor.

Second Raku Workshop - Copper Glazes Edition

in ,

I decided to try copper glazes again, but with some wild cards thrown in - I experimented more with unglazed negative spaces, and tested out some different types of glaze.

This first piece has “Midnight Luster” glaze on the interior and a lithium carbonate glaze on the exterior. It’s quite attractive in photo, but it did suffer from a bit of pitting, meaning the glaze pooled in some spots and it bubbled and hardened in ways that are suboptimal; instead of a smooth surface, there are rougher points within.

This next piece is interesting in that I had intended it to be a more standard bowl, but in the bisque firing process its sidewall accidentally got damaged and it was involuntarily edited into the shape it has now. I sanded it down a bit and decided to move forward with it; I can imagine that the cavity might improve accessibility to whatever is stored within!

I was pretty proud of this platter as a handbuilt piece, but unfortunately though it made it through the bisque firing unscathed it was unable to handle the temperature fluctuations of the raku firing and it sustained a crack across about 2/3 of its base. It is not salable now, but I still wanted to share the piece with you!

Finally, here is the most experimental piece of the metallic batch - I used both “Emerald Copper” glaze and a thinned out crackle glaze to create the exterior dripping decoration, and used “Midnight Luster” on the interior. The bottom of the exterior is just the result of carbon trapping in unglazed raku clay.

First Raku Workshop Pieces - Baked Potato Edition

in

As I mentioned in my first raku post, the “baked potato” technique involves coating the bisqueware in ferric chloride, sprinkling it with sugar, salt, and/or horsehair, and then bundling it up in aluminum foil like a baked potato before firing it. The one example piece we were shown of this technique was interesting but not super compelling, so I just tried two “baked potatoes” out in the form of a couple cache pots.

Interestingly, the resultant pieces did not come out as advertised, but I do really like how they ended up. I was told the sugar and horsehair spots would turn black, but on my piece they are mostly white with some grays. This could be for a couple reasons: A) all the environmental variables at play - the local temperature and humidity outside, the ferric chloride purity and concentration, the thickness and tightness of aluminum foil, etc. B) at the time I understood I was to put one bundling of aluminum foil on, but afterwards I heard that perhaps the instructions called for two. Reason B is all the more interesting because some of my foil burned off in the kiln, exposing part of the pottery inside. The kilns did not have organics inside beyond what was in the “baked potatoes” and had vents providing air flow, so maybe the burning of the foil resulted in less carbon trapping than would otherwise have occurred?

Due to the general inconsistencies and vagaries of raku firing and the complicating factor of my still not being sure how many layers of aluminum foil is advisable, I’m very unclear on if I can replicate the appearance of my “baked potatoes” in the future.

Here is my first “baked potato” cache pot. As you can see, it kind of looks like red marble or agate. I had the choice of sealing these pots with a gloss or matte coat. I chose the matte, which I stand by.

And this is my second “baked potato,” which was fired in the same round as the first. I do really like the appearance of these, but I’m not as convinced that it’s best suited to cache pots though it certainly will look nice as such. I’d like to try a large bowl or two with this technique next time, as I think that could be even more gorgeous - though it’s all dependent on how the firing goes!