(I hope this post follows the rules of the sub)
Let this be a cautionary tale about using steel balls in paint pots, or at least about checking carefully if they are stainless.
I don't paint regularly. So I often find my Vallejo paints separated and hard to mix. So, I decided to add (what I assumed was stainless) steel balls into them to help with that.
Now, a year later, I notice stains at the bottom of some pots. It didn't take long for me to think that they were probably rusting at the bottom. (Pics of the pots) So I used a strong magnet to pull them out and replace them with glass beads.
However, I noticed that one pot was still quite noticeably attracted by the magnet, even after removing the ball. (Video of the pot next to the magnet) And now, lo and behold, the paint is acting like a ferromagnetic fluid.
The other paints don't seem to be in that state. However, I may feel a very light force when putting the magnet next to some of them.
So, what next? Do I throw them away? Obviously I won't use the magnetic one, but the others don't seem too bad color and texture-wise. Perhaps I can still use them for terrains and bases?
That's gonna be near 40 pots that I'll have to buy back. Perhaps less now that I have better knowledge of what is useful for me or not. But that still sting a bit.
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EDIT: After reading the comments, it seems that paint can be magnetic depending on the pigments used and their amount. I wasn't expecting the magnetic force to be that strong that's for sure!
It seems that the paint is fine, I am still gonna use them. Phew!