# Plaster of Paris,Hydrocal,Sculptamold...wich is best?



## Brakeman Jake (Mar 8, 2009)

My trackwork is almost complete and I'll start scenery in a near future.What I'd like to know is what you modellers recommend amongst these products or other.

My main concern is keeping the layout as light as can be (moving purposes) so,over price and other concerns,is how well it will hold its own when only thin coats are applied.


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## J.C. (Dec 24, 2016)

I use hydrocal to me its the best combo of strength, durability and weight. you can further reduce the weight by mixing ground up bead board, but I don't and I used it on my modules.


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## fcwilt (Sep 27, 2013)

Hi,

P-of-P and Hydrocal are similar and I've used both BUT I also use Sculptamold as it, to me, serves a different purpose.

Don't think you need to chose just one.

Frederick


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## Mark VerMurlen (Aug 15, 2015)

How complex is the scenery you're trying to build? I agree with Frederick to mix different materials depending on what you're trying to build.

I generally use Hydrocal in rock molds for making rocks. Its light, can be easily broken to fit pieces together and it can be sanded down, but its also a bit brittle too. Regular P of P works well for making rocks too, but its much stronger and heavier than Hydrocal. I've also used plastic resin for casting large rock formations. Its extremely light and also very strong, but its harder to work with.

For larger land forms (hills, valleys, mountains), I use either foam or plaster cloth over newspaper wads to make those larger areas. I then put drywall mud over the base to smooth out the shape. Drywall mud is easier to reshape after its dried than any type of plaster.

If you're curious about how this might all work together, see the build of my layout at http://www.modeltrainforum.com/showthread.php?t=53721

Mark


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## Lehigh74 (Sep 25, 2015)

I would use hydrocal for rock molds, rigid foam and/or plaster cloth for rough contours and either Mold-a-Scene, Structolite or Sculptamold for the finish contour.


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## Brakeman Jake (Mar 8, 2009)

The layout is too small to allow building any logical looking mountain.It will be mostly flat land with a small river cutting through about half way.There will be a few rocks sticking out here and there and possibly a low hill or two.

The main interest will be a small yard serving a few industries (sawmill,creamery,etc) in the middle of a rural setting where cattle raising will be dominant.

In most area,plaster will only be a thin coat over pink foam that I can paint and drill to plant trees.Weight restrictions means minimal use of heavy materials.


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## fcwilt (Sep 27, 2013)

Hi,

I find Sculptamold (and like products) to be my choice for giving texture to foam.

Frederick


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## sachsr1 (Mar 3, 2016)

Don't forget all of these items are available at stores that regularly have 40% off coupons.


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## Brakeman Jake (Mar 8, 2009)

So far,the only one I could find locally is Plaster of Paris so that I may not have the option.


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## cole226 (Feb 8, 2013)

Brakeman Jake said:


> So far,the only one I could find locally is Plaster of Paris so that I may not have the option.


HOW BOUT DRYWALL JOINT COMPOUND? should have at any lumber yard.


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## fcwilt (Sep 27, 2013)

Brakeman Jake said:


> So far,the only one I could find locally is Plaster of Paris so that I may not have the option.


Hi,

Do you have Amazon up there? That's where I got my Sculptamold.

Frederick


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## Nikola (Jun 11, 2012)

Curious, if weight, avaialability and cost are issues, what about styofoam packing peanuts and those inflated plastic bags Amazon uses as cushioning?


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## CTValleyRR (Jul 26, 2014)

Different products for different purposes. I find plaster much better for casting, but for general terrain, I use Sculptamold. It is much more durable.

As far as getting Sculptamold, use Amazon.com


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## santafealltheway (Nov 27, 2012)

If you're just going for a basic covering to prepare everything for trees and stuff, I prefer plaster CLOTH. then you can use the hydrocal for your rocks and other details on top.

you can get a huge box on amazon pretty cheap.


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## Brakeman Jake (Mar 8, 2009)

I guess I'll settle with Plaster of Paris wich I can get locally at reasonable prices.

I could find some of the suggested products on Amazon.Ca but the prices are totally crazy,not counting shipping.


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## DMASSO (Jul 25, 2015)

I like to us structolite. It is a course base coat material that drys overnight so you have more working time. It gives you a textured surface that you can paint or add sculptamold. 
A 50 pound bag at Home Depot costs about $12.


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## CTValleyRR (Jul 26, 2014)

santafealltheway said:


> If you're just going for a basic covering to prepare everything for trees and stuff, I prefer plaster CLOTH. then you can use the hydrocal for your rocks and other details on top.
> 
> you can get a huge box on amazon pretty cheap.


For making hardshell over newspaper balls, cardboard webbing, window screen, etc, plaster cloth is very good, although you still have to cover it with a thing layer of something to eliminate the gauze texture.

For covering rough extruded foam shapes, though, it's a waste.


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## Brakeman Jake (Mar 8, 2009)

There are times I wish I'd live in the U.S..Not a single local supplier (including three Home Depot) carries either Structolite or Sculptamold.


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## Nikola (Jun 11, 2012)

Whatever happened to good old paper mache?

And why, nowadays, does everything have to be a specialized product? Whatever happened to basic fundamentals?

(BTW, yes, I am a very, very old person.)


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## cole226 (Feb 8, 2013)

Brakeman Jake said:


> There are times I wish I'd live in the U.S..Not a single local supplier (including three Home Depot) carries either Structolite or Sculptamold.


Jake, supposedly this link ships to Canada. :dunno:
Joannes Fabric and Crafts

http://www.joann.com/amaco-sculptamold-modeling-compound-3-pounds/3419389.html

wonder how bad it will be you up with shipping?


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## Mark VerMurlen (Aug 15, 2015)

Nikola said:


> Whatever happened to good old paper mache?


I haven't considered paper mache. Isn't it made with flour for the paste? I'd be worried that it would rot over time, could attract vermin, etc.

Mark


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## CTValleyRR (Jul 26, 2014)

Mark VerMurlen said:


> I haven't considered paper mache. Isn't it made with flour for the paste? I'd be worried that it would rot over time, could attract vermin, etc.
> 
> Mark


Except that you're going to paint it, add scenery, etc, which protects it. My only objection to it is that it has to be applied in very thin layers, otherwise it is crumbly.

Like everything else in this hobby, you use what works best for you.


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## Brakeman Jake (Mar 8, 2009)

Indeed,in the hobby you use whatever works well for you or whatever is available to you at a decent price.I did some research with highly surprising results.

Only three local building suppliers stock Plaster of Paris and their prices range from $4.99 to $6.49 (CDN$) for the very same 2 kgs. box.

Then I searched the web and got a huge surprise.The very same 2 kgs. box (DAP) is $30.81 at Walmart.ca and $32.82 at Amazon.ca.Totally crazy if you ask me,they must think that us Canadians are either millionnaires or stupid,or both.

Thinking of possible misprints,I searched a little more and found:
Walmart.ca...
-Hydrocal,1/2 gal.:52.66,Sculptamold,3 pds.:27.56 and Structolite,50 pds. for 65.71

Amazon.ca...
-Hydrocal 1/2 gal. is 57.06 and 2.3 kgs. is 128.84
-Sculptamold 1.4 kgs. is 69.20 and 50 pds. is 167.99

Can somebody explain to me?


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## CTValleyRR (Jul 26, 2014)

Well, roughly 30% of the price difference is due to the exchange rate. 

Now, are you talking delivered price, including all taxes, shipping charges, etc?

Because I can get the 3 pound bag (your 1.4kg) of Sculptamold for as little as $10.56 (delivered); or as high as $64.90 (USD) -- all listed on Amazon. Similar price variances from different vendors (in the Amazon Marketplace) exist on the other sizes. With Marketplace products like this, you really have to look at "See All Offers" to find the best price.

FWIW, though, last time I bought a 50 lb bag, I paid less than $50, delivered.


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## Fire21 (Mar 9, 2014)

Some years back I was experimenting with making hills. I wadded up newspaper, taped them into a sensible shape, and covered it with paper towels dipped in thin P of P.

It set up quickly and was amazingly strong. It absorbed watercolors well, which made it easy to do scenery. Being a thin layer, it pokes through easily to install trees and brush.

Sprinkling a little P of P powder onto the newly-laid towels makes for a bit thicker and stronger layer.

I'd think similar work with Hydrocal or Sculptamold would work about as well.

Hint: after it's set up, remove the paper wadding...it reduces fire danger.


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## Nikola (Jun 11, 2012)

Fire21 said:


> Some years back I was experimenting with making hills. I wadded up newspaper, taped them into a sensible shape, and covered it with paper towels dipped in thin P of P.
> 
> It set up quickly and was amazingly strong. It absorbed watercolors well, which made it easy to do scenery. Being a thin layer, it pokes through easily to install trees and brush.
> 
> ...


There you go. And instead of newspaper, go right back to my earlier suggestion of styofoam packing peanuts and those air-bladder bags Amazon uses. Even inflated baggies. Lightweight and free.


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## Brakeman Jake (Mar 8, 2009)

Thanks to all who pitched in with infos,I wanted to know if there was any lighter materials than Plaster of Paris and indeed there are.Unfortunately,none of them are locally available here so P of P remains my only logical option.

Though a little heavy,a careful application of thin coats should keep the weight penalty minimal.I'll buy a 10 kgs. bag that may well be all I'll need for my moderately sized layout (44 sq.ft.).


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## tr1 (Mar 9, 2013)

*Rock mold castings and water based washes.*

If "Hydrolcal"..... (a casting plaster) is available in your area? I would definitely recommend to try and use that type of plaster. The "hard shell scenery" technique popular in the early 70's accepted mineral spirit washes of oil paint quite well.
Rock castings can also be added to the mountainous effect.
the casting plaster is strong and light weight.
There is also water based washes available now through W. S. I have yet to try those.
water based washes. That is in the future. Mineral spirits in doors?:dunno:
Regards,
tr1


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## Nikola (Jun 11, 2012)

I wonder if you could lighten the P of P by mixing in sawdust.


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## CTValleyRR (Jul 26, 2014)

Nikola said:


> I wonder if you could lighten the P of P by mixing in sawdust.


Well, that's essentially what Sculptamold is, except that it uses shredded paper instead of sawdust, and adds a little powdered white glue as an additional bonding agent.


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## Nikola (Jun 11, 2012)

CTValleyRR said:


> Well, that's essentially what Sculptamold is, except that it uses shredded paper instead of sawdust, and adds a little powdered white glue as an additional bonding agent.


Hmm. Then get a barrel of shredded papar from a shredding company. Free free free.


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## traction fan (Oct 5, 2014)

*Lightweight scenery*

Brakeman Jake;

I just read through this entire thread, and I'm surprised no one suggested extruded foam Insulation board. It's very light, easy to cut and sand into shape and with the cold weather in Canada, I would think the local Home Depot would carry it. You can cut down into it for ditches, rivers, road underpasses, etc. that are below track level. It ca be cut, and stacked up like layers of a cake to make hills. When you have everything shaped the way you want it, you can paint it with dirt brown latex house paint and sprinkle on finely sifted real dirt. Ground foam atop the dirt for grass, bushes, etc. Poke in a few hundred thousand model trees, and you have Canada. Using foam, you don' need any plaster at all, unless you just want it. You can even buy, or make your own, rock castings from foam. For filling in small holes and cracks I use Elmer's wood filler, sold at Walmart and Home Depot. 

Regards;

Traction Fan:smilie_daumenpos:


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## Brakeman Jake (Mar 8, 2009)

Traction Fan,
you're right.Here in Quebec,all construction suppliers carry the pink insulation foam in one and two inches thicknesses and I've already made intensive use of both.My layout is made of two inch foam glued to 3/8" ply grid frames,lightweight and quite strong.I then added the one inch foam under the trackage.

To keep the weight as low as possible,there won't be any mountains and plaster will be used in only a few areas.Shaped foam will be most of the scenery.

I haven't started any scenery yet so I believe I'll have some experimenting along the way.How well water based paints hold on foam?Solvent based paints will melt the foam,that I know.I may have to coat the foam with plaster mainly for this reason.


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## CTValleyRR (Jul 26, 2014)

traction fan said:


> Brakeman Jake;
> 
> I just read through this entire thread, and I'm surprised no one suggested extruded foam Insulation board. It's very light, easy to cut and sand into shape and with the cold weather in Canada, I would think the local Home Depot would carry it. You can cut down into it for ditches, rivers, road underpasses, etc. that are below track level. It ca be cut, and stacked up like layers of a cake to make hills. When you have everything shaped the way you want it, you can paint it with dirt brown latex house paint and sprinkle on finely sifted real dirt. Ground foam atop the dirt for grass, bushes, etc. Poke in a few hundred thousand model trees, and you have Canada. Using foam, you don' need any plaster at all, unless you just want it. You can even buy, or make your own, rock castings from foam. For filling in small holes and cracks I use Elmer's wood filler, sold at Walmart and Home Depot.
> 
> ...


Well, I didn't recommend it because I've been beaten with the RTFQ (Read the Freaking Question) club once too often. He didn't ask about it, maybe because he's only looking for something to cover his foam.


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## CTValleyRR (Jul 26, 2014)

Nikola said:


> Hmm. Then get a barrel of shredded papar from a shredding company. Free free free.


Sure. But cost isn't the Holy Grail for me that it is for some. By the time I have paid for the plaster and glue and collected the shredded paper and spent the time to mix it together and find a suitable storage container, it really isn't "free, free, free". Based on what I've paid for Sculptamold in the past, it is more _cost effective_ (notice I didn't use the term "cheaper") to buy it.

Same analysis applies to most things in this hobby for me. Everyone is different, and has different priorities, but money isn't my scarcest resource. Time is. By a long shot.


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## Nikola (Jun 11, 2012)

CTValleyRR said:


> Everyone is different, and has different priorities, but money isn't my scarcest resource.


God bless. I'm poor. And still have no time, either.


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## traction fan (Oct 5, 2014)

*Acrylic house paint*



Brakeman Jake said:


> Traction Fan,
> you're right.Here in Quebec,all construction suppliers carry the pink insulation foam in one and two inches thicknesses and I've already made intensive use of both.My layout is made of two inch foam glued to 3/8" ply grid frames,lightweight and quite strong.I then added the one inch foam under the trackage.
> 
> To keep the weight as low as possible,there won't be any mountains and plaster will be used in only a few areas.Shaped foam will be most of the scenery.
> ...


Brakeman Jake;

Water-based, acrylic house paint should stick to foam very well. You won't really need to coat the foam with plaster, or anything else, to paint it. Actually, I've used a fresh, still wet, coat of acrylic house paint as "glue" to hold track to wood. Works fine. You could probably do the same with layers of foam, if you wish. You are right about solvent-based anything being potentially bad for foam, yes, some solvents can dissolve the foam. If you need to glue foam, use Elmer's-type white glue, yellow carpenter's wood glue, or "Liquid Nails FOR PROJECTS" which is safe for foam. Regular (not specifically labeled "For Projects") "Liquid Nails" is solvent-based and can ruin foam. 

regards;

Traction Fan:smilie_daumenpos:


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