"baked potatoes"

April 2023 Raku Crackle and Saggar Ceramics

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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.

First Raku Workshop Pieces - Baked Potato Edition

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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!