Plaster for concrete

Discussion in 'HO Scale Model Trains' started by Gary S., Sep 16, 2007.

  1. Gary S.

    Gary S. Senior Member

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    Today I did my first ever plaster in a mold kind of thing. It turned out great, and now I want to do more! I'm trying to think of all kinds of stuff I can add to the layout using this method.

    Today's project consisted of some small concrete retaining walls around a ditch with a culvert. I built some forms out of styrene right there on the layout, similar to how it would be done in real life. I coated the plastic with a bit of vegetable oil so the plaster wouldn't stick. Then I mixed up the plaster and poured it in the forms. I let it dry a few hours, removed the plastic forms, and man it looks great.

    I did put a little black paint in the plaster as I was mixing it, and actually I put too much, the plaster is too dark for concrete, but it can be painted.

    Sorry, no camera this weekend, but will post some Tuesday evening.
  2. doctorwayne

    doctorwayne Active Member

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    I cast some of my bridge piers and abutments, using Durabond patching plaster in homemade styrene moulds. Like you, I wiped on some vegetable oil as a mould release, using a paper towel. Most of the moulds were two-piece types, with external stiffening ribs where required. I made mine so that they were upside-down while being filled, which allowed me to use the same mould for similar piers of varying heights, as on the bridge shown below.
    [​IMG]

    The big abutment to the right was cast in place using a three-sided mould held in place with lots of wood.
    [​IMG]

    As were the abutments on the ends of both bridges here:
    [​IMG]

    The piers for the Maitland River bridge were all slightly different due to the need to accomodate various styles and sizes of bridges, and both abutments were unique. I've got a box full of moulds, now! :rolleyes:
    [​IMG]

    However, for this bridge, the piers are stacked .060" styrene sheet, with abutments built up from more .060" sheet.
    [​IMG]

    Casting is lots of fun, and the Durabond sets up in about 90 minutes, so you don't have to wait too long to see the results. While it's very hard when fully cured, there are several hours where it's possible to carve in mortar lines for brick or stonework, and you can even use an X-Acto to carve in some relief on the faces of the individual stones.

    Wayne
  3. Gary S.

    Gary S. Senior Member

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    I had considered building my ditch retaining walls out of styrene. But I remember looking through model railroad magazines back when I was a kid in the 60's and thinking that casting stuff out of plaster was just so cool. It defined the hobby for me to a certain extent. And now that I've done it, I can't help but think that I have finally arrived! :thumb:

    You mentioned Durabond. Is that available at hardware stores? I used regular ol' plaster of paris.

    I am mildly wishing that I had choosen a more "scenery intense" area to model instead of just an industrial park on flat land. Your bridges look awesome! And I am finding myself looking for places on my layout where I can cut in some creeks and drainages. Believe me, I'll find some places to do some more casting.
  4. MasonJar

    MasonJar It's not rocket surgery

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    One of the recent MR had an article on casting concrete things (they did a small deck bridge for spaning a creek) from "anchor bolt" cement - a very fine grain cement powder normally used for filling holes and anchoring fastners. Results looked great. Maybe worth a try...

    Andrew
  5. doctorwayne

    doctorwayne Active Member

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    Gary, Durabond is made by Canada Gypsum, although I believe U.S. Gypsum makes a similar product. I got mine at a building supply store - try Home Depot or Lowes. The proper name for what I used is Durabond 90: the "90" refers to the setting time, in minutes. I think that there's also a "20" and a "60", and there may be others. Like Hydrocal or dental plaster, it contains a catalyst, and will set in approximately the stated time, regardless of how thick or thin you mix it. Depending on the thickness of the application, it can take quite a bit longer to fully harden, but is very hard when fully cured. One of its advantages is that it doesn't crack when applied thick, as does drywall mud. I used it for all of my basic landforms, applied over window screen. It also sticks well to wood (dampen the wood first) and it was used over plywood to form the "water" in my rivers. It comes in 1 lb., and 5 lb. boxes and also in 15 kg. (33 lb.) bags.
    As for "scenery intense", the areas around those two bridges over the Speed River and the High Bridge will both be covered with trees, with a lot of the bridge structure hidden. Many of the adjacent trees will be taller than the bridges, which should help to make the area look less spectacular, but still keep it interesting.

    Wayne
  6. Gary S.

    Gary S. Senior Member

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    Andrew, I remember reading that article about the anchor bolt cement. I'll have to see if I can find the article and the product to try it, either that or the Durabond product.

    Here are two photos of the ditch retaining wall with culvert.

    Edit: Oops, the first photo is the wrong photo. I'll get the other one.

    Attached Files:

  7. Gary S.

    Gary S. Senior Member

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    Here is the correct photo:

    Attached Files:

  8. TruckLover

    TruckLover Mack CH613 & 53' Trailer

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    WOW Gary, AWESOME job!!! I love the retaining wall and culvert. Those roads look sweet too, those are drywall compound right?
  9. doctorwayne

    doctorwayne Active Member

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    Gary, both the road and the culverts look good. I like the crossings, too. :thumb:

    Wayne
  10. Gary S.

    Gary S. Senior Member

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    Thanks guys!

    Josh, the roads are made out of "foam putty" which is a lightweight alternative to drywall compound. Eveyrhting still needs paint/weathering, that will come later.

    One more similar photo:

    Attached Files:

  11. TruckLover

    TruckLover Mack CH613 & 53' Trailer

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    awesome, well the roads look great, where can one get this "foam putty" ??? At the local home depot or lowes? :mrgreen:

    I mean, you had awesome results, I would like to give it a shot too :thumb: :mrgreen: :mrgreen: :mrgreen:
  12. MasonJar

    MasonJar It's not rocket surgery

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    Josh,

    The "foam putty" may also be labelled "lightweight spackle" or "lightweight patching compound". It comes premixed in a tub like margarine. You know you have the right one when you find the container weighs about half as much as the other premixed stuff.

    Andrew
  13. TruckLover

    TruckLover Mack CH613 & 53' Trailer

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    hehehe thanks Andrew, imma go and get some today, Im anxious to try it out, Gary had awesome results and im always willing to try new stuff for roads :mrgreen: :mrgreen:
  14. Gary S.

    Gary S. Senior Member

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    Josh, I mixed some black craft paint into the putty which gave it the gray color. It dries a little lighter than it looks when wet. I had to do several applications with a putty knife that was a little wider than the road. It helps to smooth the putty if you wet the knife.

    The putty will end up wider than the road, possibly with some big glops. Don't worry about that, it will come right up. Also, I made the roads a bit wider than the final result. After it dried, I went back with a hobby knife and cut the excess foam away and pulled it up, leaving a nice edge.
  15. TruckLover

    TruckLover Mack CH613 & 53' Trailer

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    Sweet thanks for the tips Gary!!! Ill be adding in some black paint too :mrgreen:

    So you apply the first coat, let dry and then come back a couple more times and apply more to get a smoother finish? hmmmm that sounds like what I did with the WS Smooth-It stuff lol, only im sure you get alot more for what you pay for with the foam putty then the WS stuff lol.
  16. Gary S.

    Gary S. Senior Member

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    Yep on all accounts.

    I did several layers to build up for the grade crossings, plus there was a learning curve on getting smooth results. Apply, let dry, apply again, the bottom coats can be used for practicing. I still need to do some touch-up and mild sanding, then some weathering. Once I add stripes, I think it will look good.
  17. TruckLover

    TruckLover Mack CH613 & 53' Trailer

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    Cool!!! Ill just have to member to be patient with it lol Im glad you told me about the water thing, that will for sure help smooth it out nice :mrgreen:

    What are you going to use for stripes?
  18. Gary S.

    Gary S. Senior Member

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    Right now, I am considering masking everything but where the stripes go and spray them. I think that would be better than brush painting.
  19. TruckLover

    TruckLover Mack CH613 & 53' Trailer

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    I was thinking more along the lines of pinstripping, I heard you can find white and yellow pinstripe tape at most aoutomotive stores I have yet to go and look tho, Thats pretty much all I have left to do on my photo diorama, I think ill head over to the pep boyz to or something.

    I know Deano uses pinstriping tape for his roads, I forgot where he gets it from tho