rock wall construction questions

[ranegyr]

hi ya'll. i am new here. i appreciate all the information you have provided.

i started a rock wall this weekend. i began with polystyrene. i broke the foam into small pieces to resemble rocks. i glued together with liquid nails. i had a pretty sturdy foam wall. i applied a sanded tile grout (very soupy mix) with a paintbrush. it looks great after the first coat. but the weight of the grout makes it flimsy. and when i touch the piece, it feels like week old cake icing. there is a thin layer of grout that crumbles under any decent amount of pressure. now, i know there has only been one coat, and a half cooked egg looks pretty nasty too. i am just worried that i did something wrong and it will be a waste of time to apply the 3 or 4 extra coats. then the 5 or 6 coats of sealer. am i being paronoid? if any of you know that this is normal please let me know, and i'll continue. it takes about a half hour to do one coat of grout, it's a big commitment and it looks wrong.

[bgmike64]

No waste of time at all. Your next coats will be a bit thicker and you'll have that problem solved. Be patient, i think you're on the right track......

[ggazonas]

make sure you cover it with epoxy so that styrene aor anything in the grout doesn't leach out over time

[melas]

Yes your rock wall will MUCH more sturdy as additional coats are applied! Stay the course and keep it wet! As mentioned, you'll definitely want to seal your concrete since you are using polystyrene (as Ed mentioned in another thread). I have been using polyethylene which, to my knowledge, does not have the problem of leaching hazardous chemicals. It is also beneficial due to the extremely porous surface - this gives the concrete a place to really anchor on. Good luck!

[ranegyr]

thanks for the info guys.
i
have a follow up question.

melas, you said keep it wet. i let it completly dry for almost 2 days. i wont be able to work on it again until later tonight. are you saying that i should mist it or just dont let it dry completly before i apply the next coat? i read in one of the posts befor i began, that people were soaking stuff in water and then finishing with vinegar since the material was for contact with water. it did something for ph. i am making this for my ball pythons and bearded dragons. it will have no contact with water in the terrarrium.

[melas]

ranegyr,

Got your PM but I will just post here for everyone's benefit. There was actually a thread asking these same questions a little while ago. I have posted the link below.

Basically you NEED water for concrete to cure fully. The vinegar stuff I really wouldn't worry much about if you are using it with reptiles UNLESS it was in constant contact with water.

See below:
Fake Rock Questions

[ranegyr]

melas,

thanks so much for the help. i read that post but couldn't find it the second time. that's the answer i needed.