"scenicing" question - rock castings and foam

11290 Oct 3, 2011

  1. 11290

    11290 TrainBoard Member

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    N scale, HCD layout. Have all of the foam carved, sculpted and want to begin adding rock castings. I have made a lot of them in plaster-of-paris and will have to blend them into the foam sculpting with either plaster or joint compound after they are added.

    My question, is it best to go ahead and add them in their raw, unfinished state and then paint/stain them after the ground covers and so forth are applied or should I try to sort of prefinish them before adding and then do the final finish after the ground covers are applied.

    This probably doesn't make a lot of sense but I have never done this before. Since it will take a fair amount of blending them into the foam faces, especially in the curve areas, if I was to prefinish, they would really get messed up with the plaster or compound and then have to be "refinished" again anyway.

    Probably best to just go ahead and glue them on and finish them in place, right? I'm learning but this phase is not going to well right now. The trials and tribulations of being a newbie.
     
  2. HOexplorer

    HOexplorer TrainBoard Supporter

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    Actually, half the folks probably color casting before application and the other half color 'em after. I do them before. So, either way will work. Personally I like to glue my casting on the foam or plaster cloth then smooth the edges with Woodland Scenic's Foam Putty. Also, I would rather you use WS light weight Hydrocol instead of plaster of paris. Neater, lighter and easier to work with. Few of us do all this stuff the same way, so ultimately you will find your own way that works the best for you. Good luck. Jim
     
  3. TrCO

    TrCO TrainBoard Member

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    I would be one who falls into the camp of 'paint after'. Not that I really know what I'm doing 'n' all, but I just figured I'd try it that way. If it doesn't work out, I'll remove them and try it the other way :) However, my reasoning for this was watching Woodland Scenics tutorial videos on youtube: they installed theirs, then painted them.

    I figure one of the advantages of painting after install is you mix up one batch of colors, and get all painting done at once without having to worry too much about storing colors... but that's just my opinion :)
     
  4. RBrodzinsky

    RBrodzinsky Staff Member TrainBoard Supporter

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    I attach them first, and use the joint compound, then do the staining. This also allows the rock face to "flow" into the surrounding ground. Do all your staining before adding ground cover and foliage, since you won't want to stain that (unless, of course, you do!). I use Aleen's Tacky Glue for the hydrocal castings. One cool thing I've noted is that the hydrocal and the joint compound stain differently, which adds the natural randomness.
     
  5. 11290

    11290 TrainBoard Member

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    Thanks, I really agree with the paint after method. As was said, the castings have to be blended into the foam hills, etc., so they would just get messed up if you tried to paint beforehand.

    I wasn't able to find any tutorials on the Tube. Maybe I need to look harder.
     
  6. 11290

    11290 TrainBoard Member

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    OK. I've attached a lot of plaster of paris rock casting to my foam with joint compound. Decided to put several of the castings on a board and try the staining technique that I saw on the Woodland Scenics video. Used acrylic paints thinned a bit more than the video as mine came out of the bottle a little thicker than the video.

    Absolute DISASTER. The stains just seemed to soak into the castings and just did not flow at all.

    Question, is hydrocal a smoother plaster type of material that does not absorb the stains as much as the plaster of paris? I got some this afternoon to try and will have some castings curing overnight to try tomorrow. If these work better, I'm going to cut off all of the castings that I currently have on the layout and start over with ones of hydrocal but need to test first.

    Just thought I might get an answer here first, before I go cutting off all the rocks. I did try painting the p-o-p castings with a 50/50 mix of white acrylic and that did seem to somewhat seal the pores of the casting and the stains did flow a bit better.
     
  7. Hytec

    Hytec TrainBoard Member

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    Hi 11290, I mix a tiny bit of black Rit dye into the water that I use for mixing Hydrocal to be poured into rubber molds. That gives a medium grey texture throughout the rock castings so it won't show white if the casting is broken. Don't use much Rit, because it apparently weakens Hydrocal slightly, also a little bit darkens the water very quickly. Once the rock casting is glued into position with Liquid Nails (Foam, Projects), I dry brush streak it with white and light pink paints for granite. Use other colors for different rocks like sandstone, shale, etc. Then I dribble green grass into the flat areas for moss and mold. I'm using rocks on my current layout that I cast over 15 years ago.
     
  8. 11290

    11290 TrainBoard Member

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    Thanks, I just poured a "moldful" to test. Had never used Hydrocal before. Decided to try it and found a box of Woodland Scenic Hydrocal at Hobby Lobby for $11.99 and had a 40% off one item coupon. They actually had a lot of Woodland Scenic stuff in the "school diorama" section of the store and prices were generally about 10% less than the WS listed pricing. With the 40% off coupons, it is a pretty good savings, and still a bit less than Tower even with free shipping.

    The spillage on the side of the mold has taken a partial cure and it just looks like it is a "slicker - less porous" surface than the plaster-of-paris.

    I'm going to let these castings cure for awhile, probably tomorrow morning late, before I try to do anything to them. Going to sail my RC sailboat in the morning first for a couple of hours.
     
  9. 11290

    11290 TrainBoard Member

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    Gave the wrong price for the Hydrocal at Hobby Lobby. I said $11.99 and it was actually $10.99 less the 40% coupon. Couldn't come back and edit post #8.
     
  10. porkypine52

    porkypine52 TrainBoard Member

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    Let me know if you get ANY of your stain mix to FLOW over the hydrocal.......it won't happen. The hydrocal will soak up any stain you use. This stuff drys rock hard and soaks up water/stain like a sponge. I have always used Sculptamold for any detailing rock castings and general all around scenic terrain. The stuff is light weight. You can paint/stain it.
    You can use drywall compound, but the stuff will crack when applied too thick.
     
  11. RBrodzinsky

    RBrodzinsky Staff Member TrainBoard Supporter

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    The staining process is more a "dabbing" process, with a foam sponge, than a paint-flowing process. If you get it wet enough, you will get some drips and runs, but most of the time, it just soaks right in.
     
  12. Wolfgang Dudler

    Wolfgang Dudler Passed away August 25, 2012 TrainBoard Supporter In Memoriam

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    I've made my "Rock Tunnel" with plaster on foam. I sanded the rock castings and glued them with white glue to the foam. Later I painted it.
    Here's the thread.

    Wolfgang
     
  13. CraigN

    CraigN TrainBoard Supporter

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    I mix WS paint to the water when I make my rock castings. i also spray the mixed water after the casting is in place.

    I make castings using both WS hydroacal or Plaster of Paris. Both work well but the plaster castings are much heavier.

    Craig
     
  14. 11290

    11290 TrainBoard Member

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    Interesting that you say that.

    I thought that would be the case also, however, I had one specific piece laying there that was PoP and I had just made the same one with Hydrocal. I always "screed off" the mold so the back of the casting was flat with the mold. Let the Hydrocal one sit for 48 hours (the PoP had been cast about 2 weeks ago) and put them on my digital gram scale ( used to fly RC heli's and used it to weigh my blades). To my surprise, they weighed almost the same, one was 20.1g and the other (Hydrocal) was 20.2g. Would never have thought it. I would have thought the PoP would be significantly heavier.

    Just my observation.

    Am working on casting some more stuff and will be pre-coloring the plaster when mixing. I've gotten the "stains" to look good on the rocks but have decided they are too dark for the layout. Going to work on something different with color for awhile.

    Steve K
     
  15. CraigN

    CraigN TrainBoard Supporter

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    When I mix the WS hydrocal, I follow the instructions to the letter because the stuff isn't cheap.
    When I mix PoP , I just add water until I get the consistency that I want. If I followed the instructions, maybe mine would weigh closer to each other. But since I was given 2 - 50 pound bags of PoP for free, I don't worry about waste.

    Craig
     

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