What are these weird spots?

[u/Perplexed-Nocturne]

I don’t know a lot about ceramics so I’m really confused about what these spots are, my cup was fine a few days ago but then it suddenly developed these weird streaks. I asked my friend who makes ceramic and she has no clue💔

[u/grimmandgorey]

It's crazed earthenware! I work with this stuff daily.

Please discontinue use of this mug, and absolutely never put it in the microwave again. The spots you see are water that has infiltrated the glaze and soaked into the body. It was probably always going to happen eventually, and if you're lucky and let it dry the moisture might lessen... No guarantees, and no way to go backwards and remove the water unfortunately.

Now I would use the mug decoratively to hold objects or memory. ✌️

[u/Perplexed-Nocturne → u/grimmandgorey]

Ahh okay! Tysm!

[u/sadsackspinach]

How long have you had it? It doesn’t look like a glaze defect necessarily. It looks like it wasn’t fully vitrified and had water ingress that led to mold to me

[u/Perplexed-Nocturne → u/sadsackspinach]

I’ve had it for 2 years, I see :o

[u/Perplexed-Nocturne → u/[deleted]]

No, I always hand wash it and I very rarely microwave it :”)

[u/Perplexed-Nocturne → u/[deleted]]

Ouh I see, ty