Welcome to brightly-fired, where I share my adventures with a microwave kiln and miniature pottery. Yes, I make pottery in the microwave! It does sometimes explode!
(not the microwave) (the microwave doesn't explode) (but sometimes. the pottery does.)
Pottery isn't new to me, but microwaving it is! I've seen a lot of people try this out in recent years, but there aren't a lot of free resources discussing how to actually... fire the pottery. So I figured, why not share what I'm learning and hopefully get more people involved in ceramics!
Here's my setup:
A microwave kiln! I use a basic kiln off Amazon, any of them for glass fusing should work, just do some research to make sure it'll fit in your microwave.
The microwave! Just a cheap microwave from Walmart. This one is 700 watts, which means I have to fire my pottery for longer, so you might have to do some experimenting depending on what microwave is available to you.
These are the gloves! Please get yourself some heat-resistant gloves. I got some welding gloves, and they work great for getting the kiln out of the microwave.
And a temperature gun! Essential for making sure the kiln gets hot enough. And making sure you don't burn yourself on your pottery.
Once I've got some tutorials made, I'll add the links here. For now, follow along as I liveblog my first microwave kiln experiments!
If you're just looking for finished pottery, check out the tag "it didn't explode!" Write-ups of my experiment process can be found under "this time for sure." Everything else is getting filed under "microwave kiln adventures." If you want to check out my other art, you can find it on my main blog, brightestofblues!
Alright! At this point I've fired everything I had prepared for the kiln, and you'll never believe this — ready? — nothing else exploded! Good news!
This gif remains true, we've only had two casualties! 🤞 with luck we won't have any more as kiln testing continues.
Once again, process below:
The big change: I preheated the pottery. I've read online that some people do this, but most of them were doing it because they had only let their pieces dry for a few days at most. I let mine dry for over two weeks, so I figured it wouldn't need it. But I think because the microwave heats up the kiln so fast, it really needs to have all the moisture completely gone, so here's what I did:
preheated the oven to 250ºF
put pottery on baking sheet in oven
left it in there for an hour
transferred pottery directly to microwave kiln to fire
I had several pieces to test: a miniature duck pond, two larger flowers, two dragon figurines, and a collection of tiny chickens.
I tested the chickens first, spacing them evenly around the kiln with the biggest one in the center. I didn't use the kiln paper to protect the bottom of the kiln this time, and I don't think it needed it really, it's looking fine even after all today's tests. I fired these for two 5-minute increments (still wasn't sure if I burnt the pieces earlier) and after cooling, they were still grey — we're shooting for a light pink, so I think the 10-minute-total firing isn't quite enough.
The duck pond went in for three 5-minute increments, and turned out paler and pinker than the chickens, so cooking for longer seems to be a step in the right direction.
Tried a dragon next with four 5-min increments. Firing went well, although the microwave got really hot. Still using the same cooling process for all of these (five minutes sitting in microwave with door open, five minutes cooling outside, then taking the top off the kiln and letting it cool to room temperature from there) and after taking it out of the microwave the temperature reading through the hole in the top of the kiln read 370ºF, which is way hotter than the last firing (that read about 260ºF through the top), meaning it's getting plenty hot to fire properly (i hope) (i hope i'm doing science right)
After sitting for a minute or two out of the microwave it made a few cracking noises.
me: little dragon, please, no, don't do this, I need you to live
kiln: *sinister cracking noises*
me: aw come on we came so far, you can't be outdone by the chickens. Don't let the chickens be my only successful pottery today. Don't do it
kiln: *popping noises continue*
But it survived! No cracks that I can see, and it actually changed colors as it cooled, from a darker grey to a light pink — truly the color we're looking for. And another note, even after cooling before opening the kiln, these guys are reading at over 600ºF, so I think they're getting plenty hot. Twenty minutes seems the way to go!
I did the two flowers in two 10-minute increments (twenty minutes total) to see how that'd go, and it worked pretty well. They took longer to turn pink as they cooled than the dragon did (I have GOT to get a time-lapse of it changing color, I bet it would be cool) but after cooling completely they're about the same color. They make a nice noise when I flick them. I'm not posting pictures of these since a friend made them and I don't know if they want them shared, but I have pics for everything else.
Last firing of the day was the other dragon, and I added the chickens, since they'd cooled to a dark grey, and I wanted to see if they'd go pink. I reheated the chickens in the oven since at that point they'd been sitting outside in the humidity all afternoon and I didn't want to repeat the morning's explosions.
Success for all! The chickens are pink and seem to have suffered no ill effects for having been in the kiln longer than their fellows after being re-fired. Preheating really made a difference with this batch. This is good, since it means I'll be able to cut my drying time in half at least — if they're going to need to go in the oven anyway, I don't think they'll need to dry for so long.
I don't have any more greenware, so it'll be a bit before I have more kiln experiments to post! I'll be sharing photos of these after painting, and process pictures of making more little dragons and other sculptures, so stay tuned! Thanks for following along.
Bit of a disaster with the kiln testing. But we persevere!
Testing the kiln means I have no idea what I'm doing and I've had to make sacrificial pottery. And you'll never guess what happened to the sacrifical pottery. Yeah. It exploded.
A complete write-up of my testing process below:
Here we go!
This is the first time I'll be testing out the kiln. I've had a few pieces drying for over two weeks now, so they should be plenty dry for firing. I'm doing all my firing outdoors, and I cannot stress this enough: do not use a microwave kiln indoors. Definitely do not use the same microwave you use for food. I have a separate microwave and I fire all my pieces on my patio with a box fan for extra ventilation. So, if you decide to try this, do it outdoors, and do it with a dedicated pottery microwave. I discuss the kiln I'm using and the microwave in this pinned post.
Some more notes about the testing environment, because I'm doing science, and that means I'm making lots of observation notes. I want to make sure I can fire things the same way again, and if something goes wrong, I want to know why — so if you embark on your own microwave kiln endeavor, take notes of your own!
it's really humid today. 75% humidity, which I am a bit concerned about, as we don't want any moisture in the pottery. As a precaution I'm keeping all the dried pieces inside until I bring them out to be fired.
It's also 90ºF outside, sunny, with a 12-19 knot wind from the west-southwest and... yeah, we don't need all the weather observations.
The plan: I'm going to start out with firing in 5-minute increments. All of the videos I've seen indicate that when the pottery is hot enough, the top of the kiln starts glowing, so that's what I'm aiming for. I've also got the temperature gun, and I want to see if the kiln will get past 1000ºF, as that's what the clay I'm using should get to in a regular kiln. Because this clay is... several years old, from an unverifiable source (I think it's this clay, but I have no way to know for sure), all I know is what it looks like after it's done firing in a real kiln. So we're really experimenting here, it'll be fun!
The first piece I'm testing is a spoon rest. Again, I'm firing in 5-minute increments until it looks like the top of the kiln is glowing. We'll see how that goes.
ominous popping sounds 30 seconds in. Not looking too good.
popping sounds continue! not sure if this is just the kiln heating up, since youtube sources mentioned their kilns sometimes make noise as they heat up but neglected to say what exactly the noises were.
this had better not be my spoon rest exploding
it smells really weird. I can see why we do this outside.
opened microwave after five minutes to test the temperature, and the outside of the kiln is now 150º
two minute break between firing to go get the box fan because now I'm worried about ceramics fumes. Why didn't I get it out earlier.
back to firing! another five minutes!
exterior of microwave has surpassed 130º. it IS hot outside but maybe I should be worried about the microwave.
it's now been ten minutes total, and the exterior of the kiln is now 160º. I feel like it should be hotter. Maybe it's dissipating when I open the microwave? but like. it shouldn't be dissipating that fast. What's up
after fifteen minutes total (three 5-min increments) the kiln exterior is now 240º! Pretty good!
since the kiln was hotter after this firing I'm going to take it out after the next one, that'll be twenty minutes total. The top still isn't glowing (what are you on about, youtube kiln people?) but it's been twice as long as some people fire their kilns for so surely it's good. Also I have no more patience.
kiln exterior is now 230º after twenty minutes. I'm letting it sit in the microwave for five minutes and then I'll take it out, let it sit outside for another five, and then open it and see what's going on.
yeah all that popping at the start? It exploded. So.
Take two! Little ceramic fish. Gonna try the same thing, but since the pieces of the spoon rest looked burnt (?) I'm going to do two 5-minute increments. Half the total time. The interior is still reading 460º even after cooling, so it's probably getting hot enough, just not on the... exterior... of the kiln... why did I think that would be a good measurement?
started popping right away. Still inconclusive on whether or not this is the sound of it blowing up so we're gonna keep going with the experiment.
stopped popping after about a minute. Good sign?
set it up for another five minutes in the kiln, but I am really not optimistic.
went ahead and took it out of the kiln to see what's up.
and you'll never guess.
What is happening here?! These have been drying for over two weeks, it's not humid inside, they're definitely dry! Can the outdoor humidity affect them that much?
ON THE PLUS SIDE, when I opened the kiln, it was over 800ºF even after cooling for five minutes, so now I know it IS getting hot enough to fire. It's just. exploding. Less than a minute in.
I'm taking a break for lunch and research. We'll see how the rest of the pottery goes!
