Since there isn’t a separate subforum I figured I’d ask here.

Context: On Sunday I made a spiral staircase around a foam block and I’ve since used Durham’s Wet Putty on it to texture it and give it the shape I want. I did a thinner layer to cover the whole thing then I used a thicker mix to create thicker walls, turned the stairs to a ramp, and raised some edges for cover.

Question: Should I use a sealer spray on the putty after I sand it down?

My plan is to base coat it in krylon’s grey primer, then water down titebond wood glue (all I have on hand), and add that powder earth pigment stuff I keep seeing everywhere. I have fine soil for the walkway and a medium grey mix for the walls. This is my first time building terrain like this. Everything else I have is 3d printed or papercraft. Thanks for any and all tips.

I'm not familiar with that product specifically, but adding a sealer is rarely a bad idea. Most often, a sealer would be used as the last step to lock everything into place and provide a little durability. If you use a spray sealer, though, you'll want to be certain that all of the foam is covered with putty or that the aerosol sealer doesn't react badly with the foam.

The same thing goes with the primer. Sealer + primer is a little redundant, especially in that order, but be certain that the foam is all covered or the aerosol may melt it.

My worry is that the putty will crack over time. My thought is that the sealer will help counteract that. Can you use sealer over the pigment? I’ve never used the stuff before.

I recommend sealer spray to protect it. Cracking may occur after it dries if you put some on too thick. Flaking can always occur, but sealer will help.