what is FEP?

fluorinated ethylene propylene

I understand that FEP is a polymer. In general polymers are difficult to solubilize, depending on their molecular mass. It is an organic polymer, so I thought of organic solvents, but FEP (or PTFE) seems to be very difficult to solubilize. See Macromolecules 1996, 29, 6548-6555.

But I found that in a recent paper:

"The FEP resin, supplied by Whitford (England) as an aqueous solution with a purity of 99.9%, was used to coat the steel substrates."

I suppose that FEP in water cannot be a solution, but rather an emulsion or a dispersion.