I was wondering if anyone has caulked (temporarily) their 18" X14"-ish Bragdon molds to their plaster clothed mts. by leaving an open pocket on the top of the mold so that the hydrocal could be poured in from the top with the mold already in place to take the curvature of the existant plaster cloth wall?
Is this feasible for a couple or 3 folks or even just one if the "pocket" method is used? I'm planning on using #s 91 and 89 weathered granites if that helps to be specific.
I'm hoping to cover the entire mt. or at least most of it with two large molds.
I'd like to wet cast so that I can follow the curvatures of my plaster cloth as much as possible but would rather not use the geodesic foam if there's a way to use plaster with the large molds while in a 2 ft. high X 18"wide vertical position.
Is this possible?
Zeroing in on what to start my secenicing with real soon.
The rubber rocks will be far too expensive for the mountain but will likely use it for the shorter/smaller cliff on the other end of the layout when I get there.
Thanks very much,
Jim
Raised on the Erie Lackawanna Mainline- Supt. of the Black River Transfer & Terminal R.R.
Hi Jim,
It's really not practical to use large molds in this fashion. The weight of the plaster causes the bottom of the mold to bulge out. It is very difficult to prevent the mold from leaking.
Your time would be better spent by taking a large plaster mold poured on a flat surface and breaking it into smaller pieces that can be contoured around your mountain. It will take far less time to fill the seams between the pieces than try and seal a mold against the mountain.
Here's a couple photos of mountains built with Bragdon molds poured flat and broken into chucks.
Hi Dave,
Thanks. I figured that was the likely path I'd ultimately have to take. I was hoping to preserve the lovely curves I've got already, but I'm sure I can pull something reasonably close off by breaking the castings up. I haven't done this before. Is there a "preferred" way to break large castings? On a table edge, etc.? Just snap 'em over yer knee?
Thanks for your great pics. Are you the guy who does this as a business in the Seattle area? (Layout construction)? Anyway your work looks really great.
Can you tell me which molds you used (if you remember) in your lower pic.? That's the look I"m after.
I score the molds on the back side where I want them to break and then break them over whatever is handy (edge of the bench works great). IIRC, the mountains above were built using molds 1, 4, 47, 82, 123, and 126.
I am indeed a full time layout builder in Seattle. Did you see the Times article on my current project, the NorthWest Trunk Lines? My crew and I have been having a LOT of fun with that project. We recently had the "Gold Spike" ceremony marking the completion of the 1100 ft. mainline.
Thanks Dave. I didn't even think about scoring (not having worked with plaster castings yet) but that makes perfect sense.
I was wondering about how to break the castings in a zig-zag pattern along the edges to better hide horizontal rock breaks/crevices. Is this not really possible or practical? Just break 'em pretty even and overlap?
I've only plopped a few Woodland Scenics outcrops (small molds) and haven't dealt with these big cliff faces.
I think I heard about you and your business on the electronics/DCC forum/threads. I'm honored that you've taken the time to help me with some basics!
I'll check out the Times link in a minute.
I'll be away from my computer for a couple of days after early a.m. I'll respond when I get back.
Thanks again,
You can get a fairly jagged edge by zig-zagging the score lines but it rarely breaks exactly the way you hope. Over lapping the molds seems to work best at giving a continuous rock face look. If you'd like to come down and see how we do it on the NorthWest Trunk Lines feel free to send me an e-mail at the address in my profile.
Dave
I've had very good success curving Hydrocal castings by waiting about 10 minutes after I've poured them. At that point, the Hydrocal is set and firm, but not yet hard. You can bend the mold with the Hydrocal in it, and the whole thing will follow a curve.
I curved this one around a form made from pink foam. It's the "easy" case of a concave surface. For a convex surface, I put a piece of plastic wrap (Saran Wrap or equivalent) over the open back surface of the casting, and then I can flip it. For a vertical surface, this might be one way to go.
On the other hand, I would suggest trying the Bragdon foam. I used it for some rock faces, and found that the scene is greatly enhanced by using this material. It takes the details of the mold better than plaster. Yes, there's a learnig curve, but it's a nice material and a way to enhance one of those "signature" scenes on your layout.
It takes an iron man to play with a toy iron horse.
Thanks Mr. B. By the way, I'm a great fan of your layout, I didn't realize that hydrocal had this property.
It seems that there are all manner of "tricks" using larger than W.S. small castings that a lot of us aren't aware of. Plop and Paste doesn't allow nearly as much finesse.
IF I don't get to my rock faces prior to the NMRA convention and National Train Show in July, I will try to attend Joel Bragdon's Geodesic clinic. I have never been able to "warm up" to foam at all even though I'm familiar with it's (sometimes) advantages.
I'm just an "organic" kinda guy, I guess
Hi Dave, I've sent a PM regarding a possible visit to see how you've broken up and placed castings.
Thanks for the offer. I'd be interested to know if you've used Rubber Rocks as well and your thoughts compared with the Bragdon molds and plaster.
Cheers, Jim
Jim,
I'll respectfully disagree with what you've been told so far. It is possible to wet cast a mold of that size. A friend of mine has a mold that approaches 48" long and we have successfully wet cast it several times. Using the method I described to you in our PM's, the plaster is thick enough to withstand running out of the mold when applied to the substrate. An extra pair of hands always helps when dealing with a mold that large.
Don Z.
Research; it's not just for geeks.
Using Grand Central Gems molds and Scenic Express Hydrocal, I have wet-cast vertical cliffs that are approx 20 x 20. I let the hydrocal stiffen till it is the consistency of tooth paste and then press it onto the plaster cloth substrate to cure. Easy to do.