I believe gunk would be the proper term?
Before bringing the iron to class, I spent the better part of an hour using this stuff
on a rag, running the hot iron over and over and over and over the rag, applying pressure and more stuff several times like the instruction on the wrapping says.
These are the after pictures.
Now to the question about gunk – how do you clean your iron?
Any advice would be highly appreciated; I would love to iron my lights without fear. If the stuff should eventually come off, you can bet it will be on light fabric..