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plaster coating on foam surface?

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plaster coating on foam surface?
Posted by gregc on Friday, February 16, 2018 4:55 PM

i built my layout on styrofoam.   track is layed on something like homasote, not foam.   I'm thinking about scenery.   One reason i used foam was that it wouldn't be as flat as plywood.  And after leaning on it here and there it is no longer flat.

and because of a cat, i've poured some plaster over parts to cover up some scratches that loosened the foam.   But i had always thought i would put a layer of plaster (scultamold or paris) over the entire thing.   I'm guessing planting a tree on paint covered foam would be much of a base for holding the trees.

i'm not interested in scultpting but sure there will be some.   just want a base the rolls up to the tracks, covered the tracks and anything else.   I'll paint it dirt color or gray for rock and work up from there

is this typically done?

 

greg - Philadelphia & Reading / Reading

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Posted by Canalligators on Friday, February 16, 2018 5:19 PM

I like that idea of leaning on the foam to give it some roll.\

I've just smeared drywall mud on the foam and/or plywood bits.  You can add subsequent coats to build it up in spots, for a natural unevenness.  It sticks to the foam or the plywood, reasonably well.  Plaster works better and can be made thicker without cracking, but the mud is cheap.

Genesee Terminal, freelanced HO in Upstate NY
  ...hosting Loon Bay Transit Authority and CSX Intermodal.  Interchange with CSX (CR)(NYC).

CP/D&H, N scale, somewhere on the Canadian Shield

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Posted by SpaceMouse on Friday, February 16, 2018 5:24 PM

I pretty much cover all my foam with drywall mud. 

Chip

Building the Rock Ridge Railroad with the slowest construction crew west of the Pecos.

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Posted by pt714 on Friday, February 16, 2018 5:35 PM

I used Sculptamold-based 'ground goop' over foam before and really liked the results-- much better than painting the foam directly, IMHO. Looking around it seems not uncommon to use something more realistic to coat foam-- its strength to me is more in its flexibility as a sub-bed, allowing contour of the land to flow above and beneath the tracks.

Phil

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Posted by mbinsewi on Friday, February 16, 2018 8:59 PM

The only area I covered the foam with plaster, is to make roads and parking areas.

The rest of all ground cover areas, were painted first, just to get rid of the pink, or blue, untill I got to scenery.

When it was ground cover and scenery time, I smoothed the surface to what I wanted, evening out joints in the foam, etc., filled the gaps with caulk, and then proceeded to use regular ground cover techniques, no plaster involved.  A coat of paint was first.

Mike.

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Posted by rrebell on Friday, February 16, 2018 9:05 PM

Plaster cloth is the only way to go, just make sure you put the buppy side up and smooth it with your hands once installed, it is amazing how many people just lay the plaster tape on one another and wonder why it dosn't stick.

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Posted by doctorwayne on Friday, February 16, 2018 9:51 PM

Canalligators
I've just smeared drywall mud on the foam and/or plywood bits.

SpaceMouse

I pretty much cover all my foam with drywall mud. 

 
Unless you're doing nothing else to these areas other than adding a little ground cover, this seems to me a kind of half-....hearted, yeah, that's the word of which I was trying to think.
No trees, no roads, no structures?  Drywall mud has almost no strength of its own, will re-soften if wetted, and don't even think about leaning on it atop foam.
 
I used Durabond patching plaster over aluminum screen for my basic landforms.  I can drill holes in it to support trees...
 
 
 
...or bash it with a hammer to level-out some bumps when I want to add to a track, like here, where the siding formerly ended just this side of the platform...
 
 
...the bashed-down areas got an application of Durabond to smooth out the dips, then track was  set atop it and pressed in just a bit.  In a couple of hours, I used some dirt-coloured thinned latex house paint to blend it into the surrounding area, then added ballast, ground cover, etc.
 
While the landforms probably won't support my full body weight, I can stand on a step stool and bend over to reach to the back of this scene, supporting most of my weight on the hillside (the bridges are removeable, when I get around to making a few hundred trees)...
 
 
I made some of my roads using drywall mud, but they don't stand up to having tools or cameras place atop them, and I'm constantly touching up the scrapes and scratches.  It looks as if I'm simulating patches, but they actually are patches...
 
 
Where the powerhouse now sits (the orange brick structure in the background), I had originally planned to add a small swampy area there, and had created a depression in the screen that, with plaster applied over it, was about 1.5" deep.  When I decided that a powerhouse would be more useful, I wet the hardened plaster, and in a single application, filled the depression with fresh plaster - solid and no cracking...
 
 
The Durabond is also useful for making durable "water"....anybody who visits here toting a camera seems to want to take photos of a train on a bridge...
 
 
 
...and there have been scores of cameras sitting atop these without any apparent damage.
 
A 33lb. bag of Durabond is somewhere around 20 bucks, and as you can see in the photo below, despite being not very thick, is surprisingly strong....
 
 

A bag will go a long way.  If you have a smaller layout, it's also available in smaller quantities.  It's also useful for casting bridge piers (seen in the earlier photos) and for use in rock moulds.
 
Wayne
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Posted by SpaceMouse on Friday, February 16, 2018 10:41 PM

doctorwayne
SpaceMouse I pretty much cover all my foam with drywall mud.    Unless you're doing nothing else to these areas other than adding a little ground cover, this seems to me a kind of half-....hearted, yeah, that's the word of which I was trying to think. No trees, no roads, no structures?  Drywall mud has almost no strength of its own, will re-soften if wetted, and don't even think about leaning on it atop foam.

Basically I was trying to cover the graininess of the foam after it was shaped. 

And I admit, there is a certain amount of a sense of ease produced after it is painted quick and dirty, with earth tone colors.

  

And since my layouts tend to be small, I can focus more on small areas. This was a section I did early on, and I learned a lot from it. 

 

So, yeah, there is a little half-ass to smearing drywall mud all over your foam--especially if that is where you plan to leave it. 

I used this layout to experiment. The section between the rails on the grades, I used cardboard, plaster and plaster cast rocks. It's hard to see because the white on white is washed out. 

But I think I prefer the foam and drywall mud.

I have not ried the durabond.

 

Chip

Building the Rock Ridge Railroad with the slowest construction crew west of the Pecos.

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Posted by gregc on Saturday, February 17, 2018 9:55 AM

doctorwayne
I used Durabond patching plaster over aluminum screen for my basic landforms.  I can drill holes in it to support trees...

this sounds useful.   I assume Durabond 90 that is sold at Home Depot is what you're referring to.

i wouldn't be surprised if plaster cracked if leaned on too hard.

how thick a coat is needed for planting trees?

and i'm glad you mentioned the power house.   It doesn't seem right to have buildings sitting on top of the layout.    Ground is never that level and it seems to me that the building should also be "planted" in the ground.

can it be mixed with color?   raw umber for dirt or slate gray for rock?

you also mentioned latext paint.   whenever i've had to same walls with latext paint, it's like rubber.  wouldn't acrylic be better?

greg - Philadelphia & Reading / Reading

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Posted by doctorwayne on Saturday, February 17, 2018 3:25 PM

gregc
this sounds useful. I assume Durabond 90 that is sold at Home Depot is what you're referring to. i wouldn't be surprised if plaster cracked if leaned on too hard. how thick a coat is needed for planting trees?

Yeah, I use the Durabond 90 (the number following the name indicates the approximate setting time, in minutes).  There are versions as quick as 20 minutes, and it also comes in smaller boxes, if you don't need 33lbs.-worth.  I apply it over the aluminum screen with a wide putty knife, then spread it around.  Once I've got it more-or-less where it should be and as thick or thin as necessary, I use a cheap 2"or 3" brush, dipped in water, to smooth-out the tool marks.

While I'm not large, I can stand atop a stepstool, bend at the waist, then place my hand or hands on the scenery, and have it support the full weight of my upper body - the plaster varies in thickness from probably 1/8" to 1/4".

That thickness will also allow planting of large trees, although when drilling the hole, the drill bit sometimes grabs the underlying screen, which may cause the hole to be a little larger than intended.  I use full-strength white or yellow glue to hold the trees in place, but they sometimes need to be supported while the glue dries.  A little additional groundcover or some bushes will hide any flaws at the base of the tree.  Many of the foreground trees in those photos scale out to about 130'HO, about the same as what I see locally in heavily-wooded areas where rather spindly-looking trees are vying for sunlight, especially where early- or late-day sunlight is blocked by abruptly-rising landforms.

gregc
...you also mentioned latext paint. whenever i've had to same walls with latext paint, it's like rubber. wouldn't acrylic be better?

When I first complete the scenic landforms, the ultra whiteness of the plaster, coupled with an abundance of fluorescent light, proved almost blinding, and I went to Walmart to find their cheapest indoor latex paint, in a "dirt" colour.
While the colour is what I wanted, trying to apply it to the irregular surface proved difficult:  the brush/paint combination was hard to move over the surface, and I soon realised that it would probably take several gallons to colour all of it.
Instead, I dumped some paint into a disposable container (plastic ice cream bucket), then added water...no particular proportions, maybe 50/50 or perhaps even more water.  That gave me a wash, which went on very easily, and went a lot further, too.  The same dirt colour, unthinned, did the muddy water in the larger river, too.
When it came time to make the water, I also picked up a grey/green which looked suitable to me - when you're looking for scenery paint in the house paint department, don't even look at the goofy names which they come up with.  Instead, look at the colour itself on the paint chip.  I used that same colour on some of the upholstery-foam background trees in some areas, too.

Wayne

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Posted by gregc on Saturday, February 17, 2018 4:10 PM

thanks

greg - Philadelphia & Reading / Reading

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Posted by rrinker on Saturday, February 17, 2018 7:10 PM

 Latest installment of Canadian Canyons on MRVP shows the use of Scultamold over carved foam scenery. 

                                  --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by mlehman on Sunday, February 18, 2018 8:31 AM

Yeah, if you like working with any o that other stuff, you'll find Sculptamold to be even easier to deal with.

Not nearly so messy as plaster or powedered drywall compounds.

Dries lighter than just about anything less.

Can be rewetted and reworked later, as well as added to or cut.

Sticks quite well to dissimilar materials.

Offers a substantial base to "plant" trees in, yet is easy to poke holes in for this purpose. Also works well for embedding plaster rock castings in.

Resists damage from moving the layout, a real advantage for modules or other layout sections that might travel.

The main objection people have to Sculptamold is that it's more expensive, but they usually base this on buying small quantities like 2 or 3 pound bags. Price out the 50 pound bag and you'll usually find it right around the $100 mark, or about $2/pound. And a pound goes a long way vs a pound of plaster. If you have some left over, seal the bag and it keeps very well, unlike plaster. I've gone back to a bag sitting under the layout for 5 years and it was as good as the day I first opened it.

The latest MRVP layout shows it's still popular with the MR staff. Look back at MR layouts and you'll find it's been a go-to solution for lots of scenery over many years. That alone is a pretty good endorsment.

Mike Lehman

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Posted by railandsail on Sunday, February 18, 2018 9:06 AM

MOLD

How well does it resist mold in ,...in a FL enviroment that may NOT be under constant AC ??

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Posted by SpaceMouse on Sunday, February 18, 2018 10:28 AM

railandsail
How well does it resist mold in

Well,

I wouldn't use drywall mud then. 

Truth be told, I probably won't use it again either. 

Chip

Building the Rock Ridge Railroad with the slowest construction crew west of the Pecos.

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Posted by gregc on Sunday, February 18, 2018 10:34 AM

it seems durabond would be a good strong base to cover soft forms like foam or screening.   Something that can be leaned on without cracking.   And sculptamold would be good on top for things that need to be shaped.

greg - Philadelphia & Reading / Reading

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Posted by rrebell on Sunday, February 18, 2018 11:19 AM

mlehman

Yeah, if you like working with any o that other stuff, you'll find Sculptamold to be even easier to deal with.

Not nearly so messy as plaster or powedered drywall compounds.

Dries lighter than just about anything less.

Can be rewetted and reworked later, as well as added to or cut.

Sticks quite well to dissimilar materials.

Offers a substantial base to "plant" trees in, yet is easy to poke holes in for this purpose. Also works well for embedding plaster rock castings in.

Resists damage from moving the layout, a real advantage for modules or other layout sections that might travel.

The main objection people have to Sculptamold is that it's more expensive, but they usually base this on buying small quantities like 2 or 3 pound bags. Price out the 50 pound bag and you'll usually find it right around the $100 mark, or about $2/pound. And a pound goes a long way vs a pound of plaster. If you have some left over, seal the bag and it keeps very well, unlike plaster. I've gone back to a bag sitting under the layout for 5 years and it was as good as the day I first opened it.

The latest MRVP layout shows it's still popular with the MR staff. Look back at MR layouts and you'll find it's been a go-to solution for lots of scenery over many years. That alone is a pretty good endorsment.

 

Funny I have plaster that is siting in sealed cat food containers that is over 20 years old, still works fine but then I recap the main container as soon as I pour out the contents into smaller containers

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Posted by mlehman on Sunday, February 18, 2018 7:56 PM

rrebell
Funny I have plaster that is siting in sealed cat food containers that is over 20 years old, still works fine but then I recap the main container as soon as I pour out the contents into smaller containers

Yeah, plaster holds up better if repackaged so that moisture can't get to it. I was refering to original containers. Sculptamold does come in a plastic bag, but with a twisttie closure in the large size, so some slight advantage over the usual plaster in a paper bag.

After several early experiences with plaster scenery, I decded to try Sculptamold and quickly concluded it had a preponderance of numerous advantages over plaster. I can see why people try plaster, but think people mostly stay with it because they haven't tried something else for general scenic base. For casting rocks, plaster still has some advatages worth considering as overcoming the drawbacks.

Not sure if the mold question was directed toward Sculptamold, but I've never had an issue with it molding, presuming you allow it to dry properly.

Mike Lehman

Urbana, IL

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