I mortised these concealed hinges into 5/8 mfd leaving an 1/8 material and its so fibrous in the hole. I could use my fingernail and go thru the board. I realize the hinge will be in there but should I coat the hole with something in case moisture gets in there?
If you’re going to finish the doors, I’d finish the inside of the hole with whatever you put on the outside. Make sure the hole is deep enough so the hinge doesn’t make a bump on the outside when you fasten the hinge.