Boar glue, hopefully?

[TheSilverH]

Usually use guineadad liners for my boys, but my washing machine is pulling its feet (I forgot to wash the work clothes ), so I’ve used some regular fleece over puppy pads. I’ve noticed a few spots like this on my purple fleece in my new boys enclosure, is it boar glue?

 

[Wiebke]

Yep!

 

[piggieminder]

It's hard to tell from the photo but it looks more like calcium deposit from urine. Is it powdery when you rub it. Boar glue set rock hard and you can't get it off!