Thanks Tim for adding this link to our discussion

Easy test! Would be interested to know if you keep that unvitrified one soaking, how long before the water saturates the mug fully? Should be able to test periodically for temperature differences between lip and base after nuking. Also, infrared gun type thermometers are $10-15 without the phone connectivity so you don't have to go by feel if you want to stay cheap. We are very good at comparative temp detection by touch, but not at guessing how much warmer one thing is than another. If 40-50 degrees difference is normal and 30 degrees difference is not, the thermometer is going to be your best bet. For greatest accuracy, you want to measure the distance between the water mug and the empty test mug. Also measuring temp from a consistent distance would be more accurate, as the size of the tested area changes with distance from the IR thermometer. A couple very minor quibbles: The laser doesn't have anything to do with the thermometer function, it's just a sight so you can aim the thermometer. Your distilled water assumptions are inconsistent. If it might matter enough to make a difference in the microwave, that would affect the absorbed water in the clay as well. So using tap in your soak bucket and distilled in your glass mug adds a variable you don't need. You would have a more controlled experiment by using tap in both situations. Distilled in both would of course be best practice, but tap in both would be preferable to tap in one and distilled in the other. The microwave explanation is actually pretty fantastic except for a little detail. The wiggling of the water molecule does not generate heat, but IS heat. Heat is just the speed of wiggle. Overall some awesome science. I extra appreciate use of a lab notebook of proper binding, dated, and recorded in pen.

In general it is dangerous to heat distilled water in the microwave. It has no particles to bubble around so it might not start visibly boiling even if it is hot enough to boil. Then as soon as it is disturbed, like by putting a tea bag in, it can suddenly boil explosively, and super hot water can get all over your hand. Since you were just doing science and not making tea, and monitoring the water with an infrared thermometer, it’s fine in this case, but just a PSA

I think you should measure the total weight before and after...

can you fix the link for testing clay bodies? thanks

interesting!! I avoid putting a lot of my PierOne dishes in the microwave because they get SOOOOO hot - now I know why!

Find a piece that has tiny cracks all over it. They do get hot. I also think that dishwashers cause ceramics to absorb more water and get these cracks.

R.I.P Samsung Classic Edition 2 microwave

Is pottery that is unsafe to microwave also not food safe even if you do not put it in the microwave?

As well Tim, I'm not sure you're Garfield glass mug, with the paint on the outside (probably 30 years old at least), is not a good test sample.

Define what would be microwave safe? It explodes, it heats up, etc.? If the water gets hot in the cup, the cup will heat up where the water is, but the handles of the cup, in my opinion, should not. To me, as long as there is no metallic in the glaze, so it doesn't explode, this should be what we're considering microwave safe. Now, as far as pottery leaking, I've had that happen with stoneware without even being put in the microwave (I tested with just plain water on my countertop). My bad as a newbie, though.

So if you make pottery can you put it in the microwave??

Hmmm, going to do some testing. What app are you using on the phone?

Iron won't heat up in the microwave, it may block heating though.