I'm glad you asked this.  "Firming" masks really don't firm anything.  This is because your skin's "firmness" is due to the amount, health, and strength of the collagen and elastic fibers in your dermis (the deeper layer of skin).   Firmness cannot be altered by any product that you put on the surface of your skin just occasionally - like a masque.  Those masks may make your skin appear a little better temporarily by shrinking the pores a little for a few hours, etc. but there is no proof that they affect collagen or elastic fibers.  I'd say don't waste your money on these. 

Topicals (creams, lotions, etc) that do build at least a little collagen are the Vitamin A creams (retinoinds) or even some of the better quality Vitamin C or alpha hydroxy products. My article on Wrinkle Repair Creams should give you more guidance on which anti-aging products are the best.   Dr. I