Homebrew PCBs

Hi, I remember reading in a post, a while ago, that after transfering
the toner to the PCB, u could seal it with a heat gun, eliminating the
porous surface, getting the same results as with the green TRF Foil.

Ive been searching for that post but I cant find it.

My questions are:

1.- Does this sealing method will work with the sponge rubbing etching
technique.

2.- If so, at what  temperature should I set the gun, and for how long
(how do I know the toner is sealed).

Thnx for your help