Why risk using the PC-7, when you can just buy Accra-Glass gel, a product specifically designed for bedding and proven to be excellent for more than 50 years? What will you save by using the PC-7? Ten dollars? You could ruin your stock.
I have used PC-7 alot in home repairs, in plumbing, carpentry, etc. But I would not use it for bedding. When it dries, it dries very hard and is almost impossible to sand.
Just my experience.
Mannyrock