I just bought a woodland scenic rubber rock mold. What can I get commercialy available to fill it with to make the rocks? I got some powder dry wall finishing compound at work, can I mix it up really wet and soupy and pour it into the mold? Or is there simply something better. I was looking for something you can pick up at a Lowes or home depot if possible.
Any suggestions ???
Pat
Plaster of Paris. That’s what I use in mine.
What you really want is some type of plaster (molding plaster, patching plaster, or plaster of paris) or Hyrocal. The drywall compound won’t set right in the mold, and you’ll end up with crumbly rocks.
Nick
I am with JW, Plaster of Paris. I have used WS’s light hydrocal, and other than it costs A LOT more, it does not work as well.
One warning on Plaster of Paris, it sets up real fast, so don’t mix more than you can use in 5 minutes.
Also, DO NOT wash tools and bucket in a sink. Use a large pail filled with water that can then be dumped out side, not in the sink. It will fill the trap and cannot be cleaned out.
Anyone tried using these molds with a thin layer of lubricant (vasoline) that you spread on the mold, then fill the mold with Great Stuff. In theroy this should work pretty good.
Another option would be to use clear caulking slightly watered down (yes with water and yes it will mix and not seperate as water is part of the curing requirement for caulk), with this more liquid caulk you’ve made, and lubricanting the mold, poor in your caulk, let drive for a day (or two would be better) and then pull it out of the mold, you’d have a flexible “rock wall” so to speak.
There are a ton of i-net articles on duplicating any sort of item using the techniques I described (and that is the cliff notes so I would suggest doing some good searching on “latex caulk mold making”)
Ooops.
I take it I have some plumbing in my future.
Jason-train said:
“Anyone tried using these molds with a thin layer of lubricant (vasoline) that you spread on the mold, then fill the mold with Great Stuff. In theory this should work pretty good.”
I wouldn’t use vaseline,it may affect the set of the plaster and it will attack latex molds.
Liquid green soap found in pharmacies and thinned about half makes a good lube and it won’t affect the set.
I use Hydrocal, and for a wetting agent I use the same “wet water” used for ballasting - a few drops of liquid dish detergent in a spray bottle. This combination works great for me.
And Chip, just think of under-sink work as another one of those engineering challenges that comes with Model Railroading…[(-D]
I have had good luck using Scuptamold.
it makes a lighter casting than regular plaster
Try using PAM or some other non-stick type cooking spray.
Try glycerine, instead.
As for the suggestion to use Hydrocal, if you want castings that are stronger than Plaster of Paris, yes, use it. However, Hydrocal doesn’t take paint nearly as well as P o P.
I think my post came out wrong. I was saying not to use plaster at all and use that “Great Stuff” expanding foam instead. My bad on the vasoline part, you’re right, it will eat latex. I thought the molds were made of plastic. I’ll assume rubber = latex though, so again my bad there. The luquid green soap I read about before so I’ll use that for my lube.
The experiments I’ve done with caulk and glycerine seemed to really delay the curing process but I’m no chemist so improper ratio’s was probably the issue there.
I’ll pick up a mold from my LHS and give it some testing over the weekend. I’m really curious now to know if you can use foam in place of plaster for these molds.
I’ve used these with Hydrocal, with good results.
I hadn’t thought of using Great Stuff. I’d guess it won’t work well, as it seems much too porous to give a good surface, and I suspect it’s going to stick to the mold. But if it works, let us know!
Hi Pat,
I use Plaster of Paris. 4 pounds for about $5 at Michaels, Hobby Lobby, Walmart, etc. I like the stuff at Michaels and Hobby Lobby better than WMTs DAP stuff which seems to be more coarse and more gray. Michaels and Hobby Lobby often have 40% off coupons in the news paper which brings the price down to about $2.50. I’ve also used the more expensive hydrocal and hydrocal light, but the plaster of Paris works just fine for me.
Ken
I forgot to mention in my previous post that I have taken to mixing some Hydrocal with P o P for my scenicking, and I’m pretty sure it would work nicely in molds. You get extra strength and retain most of the paintability of P o P.
I’m sorry Jason-train I read right over the mention of Great Stuff… I’ve been thinking about trying that stuff for some time. But I’m chicken. Might be woth fooling around with.
Hi All I use “Floor Leveling Compound”. Get it at Lowe’s or Home Depot. It comes in 20-25 pound bags, and it looks like Plaster of Paris, but has a longer set up time. You can mix it to a thick past or a runny liquid. Its primary purpose is for leveling irregularities in floor surfaces before putting down the finish floor. I don’t know by what name it is called as there are different brands and every one has a different name, so you may have to ask for it. I don’t remember the price, as I bought my bag about three years ago. It is still OK to use, as it doesn’t go bad like Plaster of Paris. I think it was less than $10 for the 20 pound bag. I have used it for Tunnel Portals, Tunnel Liners, and Stone Walls, and in rock molds. Easy to paint.
Sam
Sam is this Thin-Set? If that works it is very easy to tint with grout tint.
I guess you would spray the mold with PAM and then make a thin set soup and let it dry about 2 or 3 days. The stuf is real cheap at owes around $12.00 or $15.00 for 40#.
I’m not Sam but I know the diff, between thin-set and floor leveler. Thin set is the mortar-glue used to adhere tiles to a wall or floor.Floor leveling compound is a plaster-of-paris like material ,but harder and is used to fill irregularities in floors,particularly concrete floors before laying tile,ceramic tile or linoleum. I can see where floor leveler might be a good material to use for plaster casting.
I never thought of using floor-leveling compound. I’m gonna have to try that, just to see how it works.
Thank you for the answer. I am going to try the floor leveler.