Editing Foam Background Guide (section)

=== Step 6: Applying silicone and substrate ===
[[File:Foam background Step 6.png|right|frameless|500x500px]]
You'll need your safety equipment for this step, and it has to happen pretty fast.

Lay the tank on its side, with the side you're applying substrate to facing up.

With your gloves on, use the caulk gun to apply lines of silicone across the surface area of the expanding foam. 

The silicone will begin curing immediately, and will lose adhesiveness as time goes on, so you want to do this quickly.

Once you're done applying the silicone lines, use your (GLOVED) hands to spread the silicone evenly across the background, no more than 1/4" thick. Try to cover all of the foam.

Then, pour your substrate mixture onto the uncured silicone and gently but firmly press it down with your gloved hands - use more substrate than you think you need. 

Try to cover all of the foam.

Allow 24-48 hours for the silicone to cure, until it no longer smells like silicone.

Repeat this step until the first layer of substrate has been applied to all background surfaces.