I don't usually fill between with rock, I do it with soil and vegitation.
Dave
Lackawanna Route of the Phoebe Snow
Dave,
Do you use hydrocal for castings and filling in between them? I'm using hydrocal for the castings and I'm filling in the gaps with sculptamold. I'm told they will take the stains differently making the difference in materials obvious. I'll do a test on a few spare rocks but I'm curious if you've had that problem and, if so, how you solved it.
Thanks
I know a lot of people paint a base coat before staining, but I prefer the way the stain looks when it soaks into the hydrocal. The paint sealer would prevent that.
Marlon, thanks for the tips. I've heard the same from others about patching plaster and casting plaster not taking paint/stains the same so I plan to paint a thin coat of white on everything before applying the colored washes. Hopefully that will help without covering too much detail.
Unless I missed it, the one thing not mentioned is how to gauge when the plaster casting has set up enough to attach it to the layout. A few minutes after pouring your plaster, flex the mold. Before the plaster sets, it should crack slightly. When it does this, wet the area you're intending to place the mold, press the mold into place, applying pressure in the center and working out towards the edges. Hold the mold in place for 30-60 seconds. I let the plaster set completely before attempting to remove it. If you wet the mold with wet water before you pour plaster in it, the mold will have some residual plaster left in it, but it's easily removed.
I fill any gaps left after removing the mold are filled in with a thicker paste made from plaster. When you mix the paste, you can extend working time by adding a little vinegar to it. Hope this helps.
I've also fashioned some "pins" to hold the mold in place with wire hangers. I bend them at a 90° angle and grind a point on one end. They are easily pressed through the plaster cloth. The hole is then covered with some plaster.
Note: One thing I noticed was that if I used casting plaster for my casting and patching plaster to fill the gaps, that the patching plaster didn't take stains as well as the casting plaster.
Marlon
See pictures of the Clinton-Golden Valley RR
Thanks everyone for the additional tips and info. I think my first attempt didn't work since my hydrocal was old. The rock still felt kind of wet and chalky the next day. I've just been pouring rocks (with new hydrocal) in the molds the normal way, but I might try to place a few on the layout while still wet, especially if there's a tricky contour to deal with.
Grampy,very nice as always.
The mention of using the Artist's pallet knife is a great tip, mason's margin trowels or pointing trowels also work well. They are rigid rather than flexible and can help act like a chisel for minor carving/ chipping if the plaster starts to firm up.
http://www.zoro.com/westward-tuckpointing-trowel-6-34-x-14-softgrip-13a565/i/G4260514/?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&gclid=Cj0KEQjwk7msBRCJj67khY2z_NIBEiQAPTFjvxGS2_e_N6FUIIWfXlxxwy4feTZ7ZIUMmU4uVeqceiQaAiSI8P8HAQ&gclsrc=aw.ds
Modeling B&O- Chessie Bob K. www.ssmrc.org
Hi Carnegie Falls: This is the method I've used. I covered my plaster cloth with a mix of 1 part Sculptamold/5 parts Structolite,( a pre plaster product called a scratch coat, contains perlite that makes a rough surface). I make the mix the consistancy of oatmeal, and apply to the plaster cloth, then cover the back of the rock casting with the same mixture and then sink the casting into the wet mix, allowing the excess to squeeze out. Then I used an artists trowerl to blend the mix around the rock casting and surrounding area. I finally used a wet brush to smooth the area.
trainnut1250When placing the molds on the hard shell try varying the angles and orientation of the molds so that the eye doesn’t pick up the same rock pattern over and over. Those of us who have been doing castings for a while can spot repetitions a mile away. As you gain experience you will see what I mean. Try to disguise the shapes by placement and orientation to get more mileage from your molds.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
A tip that I omitted above, I found it a good idea to make pours of all molds. My club has numerous ones mostly WS as you have. By having a casting of the mold, you get a actual view of the final look. I have numbered the molds and also place an arrow to show reference. The casting was also marked (usually try to keep all those reference castings w/ the mold to readily use for laying out the next project). This allows you to examine all the castings and help with thier placement as weel as determine the appearance of like castings to use on the continuous cut or outcropping.
It is also helpful to "dye" the plaster to a close base color. I use powdered masonry dyes. Black, brown and oxide are most commonly found colors and what we would generally be using. The powder added to the dry plaster will show a fairly close final dried/ cured color. All the castings previously shown were done in this fashion. All that was done for final color is washes and drybrushing. This helps in not having to fully dye the entire project or painting that can tend to obscure some of the detail. e
Especially true if pouring plaster for conrete walls, abutments etc.
That "buttering" batch I mention needs to be a separate "fresh' batch, as the remaining plaster from the pour will be drying and harden at the same rate and many times faster than the pour. A small whipped up mix in a disposable cup is all thats needed. As you gain experience you will find that you can do multiple pours in a few molds at the same time. Always have additional molds washed and ready to use for any excess from that batch of plaster, They will always come in handy and you won't be wasting plaster. They can be placed elsewhere or broken up to fillin between castings. Crumbs and all sorts of random pieces can always be used for tallus.
Thanks everyone for the tips. A few months ago, I started pouring some molds to build a supply of rocks but this was my first shot at letting them set up in place. I made my first attempt last night with so-so results. I do think that "buttering" the casting with some additional plaster right before placing is a good idea. I did not do this and there wasn't enough plaster to anchor it to the base plaster. I mixed the hydrocal per the directions and it was very wet. Any extra would have just ran over the edge of the mold and on to the table. I should have left some in the mixing bowl and added it to the back of the casting as it started to stiffen up. Thinking back, I believe I started using less water than directed when I first started casting some rocks since I thought the mixture was too wet. I suppose I could also mix up a small amount of sculptamold and butter the casting with that before placing.
When I tried to remove the rubber mold, the entire thing popped off the mountain with the casting still inside the mold. Not a huge deal, since at least now the rock is formed to that countour and can easily be glued/caulked/plastered in place.
bogp40, I've seen you mention cripplebrush rocks before and I've checked them out. They look great but I think they're a bit costly for me. Depending on how good I get at placing plaster castings on curved surfaces, I may change my tune in the future!
Thanks again.
Also to expand Guy's recommendations, do a few practice pours and observe the finished casting before just filling and "plunking" on random molds. This will allow you to visualize the final castings and the actual strata/ rock type. Many of the molds can be flipped to change it's orientation, First, figure what type of rock, is it to be cut, natural erroded outcropping etc. The proceedure for filling and placement already has been explained. I do, however, find that buttering up the backside w/ small fresh batch and then placing tends to work far better for me. Once the plaster starts to thicken (propped up molds w/ wadded paper towel to level), lift edges to check progress so not too wet, the surface of the plaster will give telltale signs as that real wet shine will start to dull significantly at the edges, the mold is ready to place. I will sometimes place an almost hardened mold and actual force the casting to crack as it is forced into the shape. That buttered mounting plaster will ooze out, but not a problem. As said the mold will continue to feel warm, keep pressure on the mold and resist the temptation to want to "peek" at the progress. Large molds may need to be held for 4-5 minutes, but this hardening will depend on the plaster itself. I have had quite fresh hydrocal dry start to "go off" in a couple minutes and harden in another few, older or just batch differences can generally cause the hardening/ curing to be various rates. Don't try to remove the mold even if the plaster feels rather hard and has cooled somewhat. I will leave them for 20-30 minutes especially for rather "craigy" thick molds. When removing mold, peel back and observe that it is releasing, especially on those rather deep detailed ones. Smoother, weather worn outcropping molds will remove quite easily. You should have previously figured the molds and a basic placement and orientation, the next mold should have bben filled about this time. Now that oozing out from the mold can either be left, if not interfering w/ subsequent placements, or you can scrape it away. I don't woory too much about voids between casings, as small broken pieces of those cured samples can be broken up and placed w/ additional plaster, cut carve and shape if needed to gain a more continuous rock face. I enjoy working w/ hydrocal, once you gain your technique you will also. If it doesn't look right to you it can always be torn out and place another on until satisfied.
If you are looking for a long cut and/or continuous face, Cripplebush "rubber" rocks are quite amazing. This cut is over 10 ft long and over 14" tall. This was done in 2 nights Enjoy, hope this helps
If you are looking for a long cut and/or continuous face, Cripplebush "rubber" rocks are quite amazing. This cut is over 10 ft long and over 14" tall. This was done in 2 nights
Enjoy, hope this helps
see stuff at: the Willoughby Line Site
Yes, wet the plaster cloth first.
No, it is not necessary to place some hydrocal/sculptamold on plaster coth before placing casting/mold.
No, the mold should not have to be pinned down while the plaster finishes drying. If timed well the plaster hardens quite quickly and will very likely stay where you put it without pinning, etc.
The plaster in the mold should be dry enough to not slip or ooze out while you are handling it and placing it on the hardshell. This can be a bit difficult to guage. Try poking the drying plaster in the mold with your finger. When it feels like it is beginning to harden is the time to place it on the hardshell.
Yes, convex placement is more likely to be successful than concave placement due to the stiffness of the WS molds. Many of the WS molds are also quite deep resulting in rock castings that are difficult to remove from the molds.
I want to try placing hydrocal rock molds on the layout while the plaster is still wet to allow the rocks to conform to the existing contours. Before I attempt this, does anyone have any tips or suggestions to increase my chances of success?
I'm using rubber molds from Woodland Scenics with their lightweight hydrocal. Base is dried plaster cloth.
Wet the plaster cloth first?
Place some hydrocal/sculptamold on plaster coth before placing casting/mold?
How dry should the plaster in the mold be?
Convex placement more likely to be successful than concave placement?
Does the mold have to be pinned down why the plaster finishes drying?
Thanks in advance.