I’ve been volunteered to create a decorative center piece of sorts for my step daughters (teacher) 1st grade classroom. Specifically painted rock cacti in little pots, example:
I’ve got the rocks painted. For pots I bought clear plastic shot glasses and painted them terra cotta color. There will be 12 glued to a tray. What I need is the filler in the little pots to hold the rocks up. All of the tutorials online suggest using sand or aquarium gravel. That won’t work as young kids are around. I thought of using plaster but that’s more trouble than I want to go through.
I thought of using Elmer’s glue mixed with sand but I’m not sure it would dry being that thick. Or would it? I also thought about some sort of acrylic material but poking around the internet leads me to believe it would be too expensive.
So what I need is some sort of medium that would dry or cure when poured that thick that’s relatively inexpensive. Any ideas?
Plaster of Paris … haha … I believe “Fix-all” is the same stuff … cheap, mixes with water, sets up hard as rock … no shrinkage … just a bit heavy but that;s to be expected …
Mixing Elmer’s glue with sand will work … it only matters that the outside 1/4" drys … except for 1st graders, they explore everything with their mouth …
ETA: Just use aquarium gravel … what could possibly go wrong? …
You can use some spray foam for insulating doors and windows. Just test a little bit in a pot because it will expand a lot over time. You can also add the rocks or gravel before it’s completely set and they’ll stick to it.
The spray foam I thought of. I’ve used it a lot in the past, the problem is there is no real good way to gage the expansion, otherwise it would be perfect. But I don’t want it to ruin the top of the painted cups.
As a handyman I use drywall compound quite a bit. Anything over 1/4” won’t reliably dry. There will also be some shrinkage involved.
I would suggest white PVA glue mixed with sawdust - the porosity of the sawdust will allow the material to dry out completely over time - and the surface can be painted to resemble soil, gravel, etc. It won’t pour, but it should be workable like a soft dough when wet.
One other thing to say: if you use plaster of paris, be careful - the reaction that occurs when it is hydrated is quite powerfully exothermic - I remember reading an account of a young girl trying to create plaster casts of both hands by immersing them in a tub of the material - it set quickly enough to prevent her pulling her hands out, and then it got hot enough to cause very severe burns (I believe she lost both hands).
i was gonna’ suggest paraffin … but, after quick check on google … if ingested, doesn’t break down so well. the substance can also be flammable … so, cancel the paraffin. as to the 16-year old girl who suffered that traumatic incident … terribly sad. she lost 8 of her 10 digits (melted) … can only imagine the horror and pain.
Drying clays typically shrink quite a bit as they lose moisture - this means they will probably pull away from the edges of the pot, as well as to either eject any embedded items, or crack around them (arguably that cracking might end up looking quite authentically desert-like, but it probably won’t)
What about polyester resin? Pour it in to near the top, will dry hard without expansion or contraction in about 24 hours. Available in any craft store or online.
Once hardened, you could pour a mixture of white glue and sand on the top and affix the cacti until the glue dries.
On reflection though, I’m not sure white glue will stick to polyester resin; but poly resin will fill space and dry hard fast without expansion or contraction.
Also, let’s face it, these are first graders. As a parent I tell you–there will be moment of praise and then either the thing will be forgotten, or it will break and then there will be a moment of tears and then it will also be forgotten. Don’t oversolve.
FWIW, you can get premixed drywall patch compound specially designed for deep fills, which sets reliably in much thicker layers than the normal stuff. It also has the advantage of being very light. But I’d probably just use plaster of Paris.
