I made my first rockscape awhile back using self leveling underlayment mix for subfloors with absolutley no problems with cracking. The downfall with it is was that in order for it to adhere to foam, it had to be relatively soupy so it was nearly impossible to add sculpting details with. Mix it any thicker, and it was tough to acheive good results in sculpting realistic final details without flaking.
So, I decided to try the grout technique for a terrarium which would be a under much more humid conditions than that of a beardy habitat. unsanded grout seamed to have better sculpting attributes BUT, i had a problem with it cracking (even with fortifying additive) especially with humidity factors which are actually necessary for a proper cure in any cement based formulation.
I am now expirementing with a 2 part technique using both products. First using the self leveling underlayment which has sand, portland cement and polymer additive for added fortification which in combination, at least i beleive, reduce the chances of cracking. Not only that, but due to a couple of its attributes, it not only sticks to whatever you slap it on in its in soupy state, (integrated polymers) it also fills everything from pockets to gaps being a self leveling formula.
Next I will layer unsanded grout for its scultabilty and color modification options over the self leveling underlayment.
My theory is that the underlayment will provide a stable substrate to conteract the foam's expansion and adherance problems vs, grout to prevent cracking, and provide tooth for unsanded grout which provides scultability and ease of pigment modification.
It is my hope that the products in tandem will provide a more realistic, foolproof and uncrackable proceedure for humid or dry climate terreria and remain tintable or paintable.
I am currently working on a small scale project to rehab an old terrarium. I have just finshed with underlayment and waiting for polymer cure to apply fortified unsanded grout. If this works out, it will most likely work for desert style terreria as this project will be for a high humidity setup where cracking seems to be more of a problem. once I know it will hold up to humidity, I will test in a dry format to be sure it works both ways,
Hopefully the two products compliment eachother. I will be sure to post results whether it is a pass or fail and the curing process involved for each scenario. Might be a while though because the current setup I am expirementing with requires a proper cure more so than a desert or arid set up would. Either way, humid or arid, as a precautionist, I think a proper cure with any concrete based product should be achieved before putting any type of animal on it.
I realize that grout has worked for many, but I have also heard of many fails as far unsanded grout with its tenency to crack, I am merely looking for a solution to stand the test of time for terraria of various habitat parameters.
Happy Bearding.