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Alternatives to plaster to coat plaster cloth

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Posted by riogrande5761 on Wednesday, August 10, 2016 4:22 PM

carl425

The discussion about texture sizes in the other thread got me thinking about how you're going to be able to create the impresssion of sandstone in your canyon. I think I may have an idea.

It'll make a hell of a mess, but if you built up the plaster a little more, then "carved" it with one of those airbrush style sand blasters, you'd be able to get the texture you want and create some of that wind blown effect.

If I could take the layout outside, I might think about giving that a try!  As it is, most of the dust has settled and been vacuumed from when I had to replace some water damaged drywall which had to be muded, tapped and sanded.  Yeah, that was fun!

Once I've finnished covering the rest of the plaster cloth with a thin layer of plaster, I may go back ove some of the vertical sections with a very thin coat of drywall mud with a smooth finish.  It does have a very fine texture that may be good for that sand stone look - I'll try painting it to some Ruby Canyon shades.  The angled parts will have some talus and some sage brush addeded.

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Posted by carl425 on Wednesday, August 10, 2016 3:40 PM

The discussion about texture sizes in the other thread got me thinking about how you're going to be able to create the impresssion of sandstone in your canyon. I think I may have an idea.

It'll make a hell of a mess, but if you built up the plaster a little more, then "carved" it with one of those airbrush style sand blasters, you'd be able to get the texture you want and create some of that wind blown effect.

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Posted by riogrande5761 on Monday, August 8, 2016 6:09 PM

A thin soupy layer applied:

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Posted by riogrande5761 on Monday, August 8, 2016 3:27 PM

That scuptamold seems to make what looks like a nice looking granite rock wall.

Rob,

I've mixed about 7 or 8 batches of soupy plaster and so far that seems to be an improvement.  Its a bit tricky to work with soupy plaster but I'm using my hand exclusively and so far it's going a bit better.  I have found that if I spray a good deal of water while I am smoothing, the water levels out the soupy plaster and helps it settle smoothly rather than whatever form it got from being smoothed with fingers, which usually leaves a pattern.  I'll try to post a few photo's later.

Thanks.

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Posted by farrellaa on Monday, August 8, 2016 9:58 AM

I use Sculptamold for almost all of my scenery, over cardboard stips and plaster cloth/gauze. I just thin it out for making thin smooth coats. I seal it with latex paint and then finish with acrylics and latex washes. For my rocks I finish with a wash of india ink and alcohol. Very easy to scupt while wet and it has a long drying time, so you can really do some finer detail carving as it sets up.

   -Bob

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Posted by riogrande5761 on Sunday, August 7, 2016 8:59 PM

Broken ceiling tile is a great idea for layered rock like shale or limestone but for massive sandstone, not the look I'm after.

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Posted by K4s_PRR on Sunday, August 7, 2016 2:56 PM

I have another suggestion.  If your mountain area isn't too large you might get away with using broken ceiling tile for a rough mountain.  We've used them on our club's modular layout.  All you have to add is one or two thin coats of your favorite topcoat material.

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Posted by Sheldon Beiler on Saturday, August 6, 2016 6:06 AM

Just Don't use  fast-patch; it sets up in a few minutes. I have found it to work well though. Once someone mixed up a large batch, and we had to you figure out uses for it in five minutes. Sculptomold also works well and doesn't Set to quickly though it does fast enough. I have found that it sets at a nice speed, but I don't know what speed you prefer.

Best wishes!

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Posted by riogrande5761 on Friday, August 5, 2016 3:30 PM

I'm on city water - seems ok but I'm not sure - something to ponder.

If I get some time this weekend, I'll give it another go with a thinner mixture.

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Posted by rrebell on Friday, August 5, 2016 1:00 PM

Some areas have hard water, or well water, this along with water treatments affects things too.

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Posted by riogrande5761 on Friday, August 5, 2016 11:21 AM

rrebell

I like Joe's formulas but one must remember that they may need adjusting for your area. Water conditions is one of things that will affect this along with temp. and humidity.

I have my dehumidifier set to around 50/55% humidity and it runs all summer long to keep it there.  In the colder months, it doesn't run so it must be dryer than 50/55%.

I'm not sure what humidity Joe has in Oregon - or if he runs a dehumifier to control it or keep it at fairly constant.

It does seem like the dried plaster cloth acts like a sink for moisture and soaks up a good deal of it - it's very noticable when I added wet plaster cloth over sections that were long dry.

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Posted by rrebell on Friday, August 5, 2016 10:46 AM

I like Joe's formulas but one must remember that they may need adjusting for your area. Water conditions is one of things that will affect this along with temp. and humidity.

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Posted by riogrande5761 on Friday, August 5, 2016 9:38 AM

wp8thsub
 
riogrande5761
I was attempting to follow Joe Fugate's guidelines as follows: "Best approach is to start with a half cup of water and maybe a cup of plaster with the baking powder retarder mixed in. Add the plaster to the water, then add a tiny little bit of water if it's too thick. And I mean tiny - as in a tablespoon or two."

 

That may work for Joe, but I find that completely unworkable.  For any brush coats I have to use much thinner plaster.  I don't use retarder.

After trying Joe's formula on 6 to 8 batches, it's time to try a thinner mix.  Joes did work but perhaps thinner may be better.

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Posted by CadizRRfan on Thursday, August 4, 2016 4:39 PM

As to "sponge sanding", I've worked one area after one application of 'mud' making a plowed field, a road and a rock strewn meadow, just by smoothing it differently

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Posted by CadizRRfan on Thursday, August 4, 2016 4:35 PM

riogrande5761

 

 
woodman

I used fabric softener sheets ( used ) dipped in plaster that was thinned with water and added vinegar to slow down the hardening of the plaster and then layed them over cardboard forms. You can use new or used softener sheets, but used sheets are a little easier to handle.

 

I've already covered all of my cardboard forms using plaster cloth, thanks.

 

It sounds as if you really are looking at relatively thin coats. My suggestion is drywall mud... I've put it on walls thicker than 1/4 inch with no cracking. The other advantage is that it can be "sponge sanded" (smoothed with a dampened sponge) even after it has fully set, thereby allowing  you to get exactly the surface texture you want. 

 

Gary

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Posted by rrebell on Thursday, August 4, 2016 12:05 AM

If you want to experiment, I have an idea that may work, I use it for roads all the time. Mix a batch of plaster to  a thick consitity and add white glue to the mix to the consitity you want, should be able to brush it on and it should stick to most anything. Try different amounts of white glue and water to get what you want.

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Posted by wp8thsub on Wednesday, August 3, 2016 7:45 PM

riogrande5761
I was attempting to follow Joe Fugate's guidelines as follows: "Best approach is to start with a half cup of water and maybe a cup of plaster with the baking powder retarder mixed in. Add the plaster to the water, then add a tiny little bit of water if it's too thick. And I mean tiny - as in a tablespoon or two."

That may work for Joe, but I find that completely unworkable.  For any brush coats I have to use much thinner plaster.  I don't use retarder.

riogrande5761
I was doing about 1 cup plaster in June before things got to busy for me to work on the layout; is 1 cup plaster a small enough batch? 

My usual batch is about one 16 ounce disposable cup each of plaster and water.  Something smaller should be fine.

riogrande5761
Yes, it's very evident that a finish surface isn't possible with one coat which is ok.  I'm guessing two coats is needed, one to cover the paster cloth and hide the shapes of the layers and pieces laid down, and a second to provide a surface finish

Multiple coats vary by location.  I may use only say 3 brush coats with one finish coat (2 plasters to 1 water) on top of it, or several more depending on what needs to happen with the final shape.

Rob Spangler

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Posted by riogrande5761 on Wednesday, August 3, 2016 6:50 AM

trainnut1250
Jim,
Making any kind of rocks, especially the type you are talking about here will take some careful work planning angles, outcroppings and forms. In looking at the amount of rocks in your pictures, you are talking about a fairly large project!!

Well, TBH, I'm going for the basics here first and crawling before walking and later running.  I tried to get the fundemental land form with the cardboard strips and obviously am not going to achieve a faithful replica of types of canyon walls in Ruby Canyon area, but hopefully a general feel and look of it.  I'll start with something more crude and see how far I get with the level of detail etc.  I'm not getting super ambitious but just wanted you to see the type of landforms I'm shooting for, which is very different from your typical model railroad scenery.  To me starting off with a smooth surface seems to make sense and then I can add on talus, and perhaps shape some parts by adding on more plaster or sculptamold or whatever works best.

 

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Posted by gondola1988 on Tuesday, August 2, 2016 4:59 PM

I use the blue foam for my scenery, after I carve it to my liking I put some drywall compound in a separate bowl I water it down to a thin paste. Then I can either brush it on or throw it on, I also add the base color to it as I thin it down. It has worked for me for years and because it s thinned down it dosen't crack.

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Posted by mlehman on Tuesday, August 2, 2016 4:44 PM

Some good pics down the page of Ruby Canyon at the Western Rail Images website of photos by Jim Ozment, long time Rio Grande employee. There is on a steam shovel loading dump cars that captures the grit well, with some representative scenery in the background.

http://www.westernrailimages.com/keyword/canyon/

Jim,

Is the sloping talus at the base of the taller rock faces essentially weathered sandstone? I haven't looked at the geology like you have, just remembered the basic of Western landscape, but I'm thinking yes. Then getting that final look can be broken down into getting the slope right, then finishing it gritty. So first part structural, the second part is applying the finish.

I mentioned the texture paint I used earlier in a general sort of way in getting the shortest path from here to there. But there can be a lot of different grits mixed in paint in the premixed. I'm pretty sure you can get textures to add to paint yourself. Go finer ius my advice, but for these slopes you'll likely want a more mixed look, so getting one grit in your paint and having another one or two in other sizes available to mix in may point towards a finishing mechanism once you get the structiral part squared away.

Mike Lehman

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Posted by trainnut1250 on Tuesday, August 2, 2016 2:00 PM
Jim,

In looking at the canyon shots, I can see what you mean. Malcom Furlow and others have done this type of rock effectively.  I was under the impression that you were talking about smoothing out the base coat – not the finished texture.  Making any kind of rocks, especially the type you are talking about here will take some careful work planning angles, outcroppings and forms. In looking at the amount of rocks in your pictures, you are talking about a fairly large project!!

 

Even with smooth sand stone, you are still going to have to come up with some rock textures and forms beyond the basic hard shell.  The sandstone is fractured and does have edges and distinct lines in it as well as area that have big piles of debris.

 

It would seem to me that question here would be whether you are going to hand carve/form these rocks or whether you are going to use molds. I don’t think you will get the results you want by merely painting plaster on the hard shell surface. You’ll want more texture and distinct rock features to capture the look. This will require some method of building up depth on the surface of the hard shell. If you go the hand forming method, working in small sections and using the slow set plaster or other slow set materials would be the way to go.

 

Molds could work as well. Bragdon (https://www.bragdonent.com/smpic/item2.htm) has lots of molds that could work for this type of rock with some careful blending. Molds are a much quicker way to go if you can find the right rock forms

 

While plaster can work for this, many others have used foam successfully for these types of rock as well. I might suggest that you make a rock wall diorama as a test (I have made many) to see what techniques will work for you. There are lots of ways to smooth out the plaster while it is still is the semi-set state that will give the texture you want. The 45 minute setting drywall joint compound (not the stuff in the bucket) would be the place to start after creating some basic rock shapes…

 

Way too much from me…

 

Guy

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Posted by riogrande5761 on Tuesday, August 2, 2016 1:08 PM

Guy,

In my case, I'm am actually not working on scenery that looks like most of the scenry I see posted - I can't see your photo's until I get home since your photohost is blocked here.  I'm interested in Ruby Canyon (google it) where there are smooth sand stone outcrops (massive sand stone which is not laminated).  Seems that the typical layout goes for limestone or shale layers or outcrops of granite.  Much of what is typically done isn't going to work for me in terms of appearance or finish.

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Posted by trainnut1250 on Tuesday, August 2, 2016 12:43 PM

 

Jim,

What is the final coat going to be over the hard shell? If you are going to put rock castings on the surface, you don’t need a completely smooth surface - Ditto for just about any type of ground cover. You do need to get a relatively smooth finish but ground foam, dirt, etc, will smooth out brush marks and other imperfections.

Here is an example of what I mean – sorry about the photo quality here:

 

The scene with basic hard shell in. Very bumpy and lumpy.

 

 

 

 

Here is the scene with some rock castings on the face and a few layers of plaster in the foreground to build depth. Notice the dirt around the tracks to build up the level as well.

 

 

 

 

 

Some basic ground cover in place:

 

 

 

 

Here is the scene finished to its current state (there will be a flume in the area someday – it is in pieces ion a box right now). Notice how the grass and rocks have pretty much long since covered the original hard shell.

 

 

 

Just about any of the methods mentioned here or in the MRH thread will work for you. Dive in!! This is just an intermediary step along the way. There are gonna be do overs and mistakes – it’s part of the process and part of the fun…..

 

Guy

 

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Posted by riogrande5761 on Tuesday, August 2, 2016 12:11 PM

rrebell

First off you need to smooth the plaster cloth when you apply it. Plaster cloth ussually has two sides, one has more plaster than the other and that is the side you need to face up. You need to get your hands dirty to smooth it.

I did that already, yep, smoothed it with my hands spaying on a mist of water as needed, which helped to also spread around the plaster that was impregnated in the cloth.  

The plaster cloth I used did not appear to have any difference one side vs. the other, however it went on very well and gave me a nice cover over the cardboard strips. The process of applying the plaster cloth went very well and I am very satisfied with the results.

As stated in the original post, I'm looking to cover it all with a thin layer to hide the squares of the cloth and their edges, which overall are fairly even and smooth.  It shouldn't take much.   

When you need to add plaster over the plaster cloth, you need to wet the cloth very well and use a thick soupy mix of plaster.

 

The consensus is I will need to make the plaster a little soupier than I did on my original 6 or 7 batches appied so far as they did set up a little too fast, even with baking powder added; I'd prefer prefer a little more working time - like 15 minutes or so.  Conclusion, spray down the plaster cloth before applying and use thinner plaster.

I do appreciate the other options offered and might give them a go too so I can see what ultimately works best for me.  Hopefully in a few years I'll be able to build a bigger layout - this 10x18' is hopefully practice for something larger.

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Posted by rrebell on Tuesday, August 2, 2016 11:02 AM

First off you need to smooth the plaster cloth when you apply it. Plaster cloth ussually has two sides, one has more plaster than the other and that is the side you need to face up. You need to get your hands dirty to smooth it. When you need to add plaster over the plaster cloth, you need to wet the cloth very well and use a thick soupy mix of plaster. 

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Posted by riogrande5761 on Tuesday, August 2, 2016 8:34 AM

woodman

I used fabric softener sheets ( used ) dipped in plaster that was thinned with water and added vinegar to slow down the hardening of the plaster and then layed them over cardboard forms. You can use new or used softener sheets, but used sheets are a little easier to handle.

I've already covered all of my cardboard forms using plaster cloth, thanks.

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Posted by woodman on Tuesday, August 2, 2016 8:07 AM

I used fabric softener sheets ( used ) dipped in plaster that was thinned with water and added vinegar to slow down the hardening of the plaster and then layed them over cardboard forms. You can use new or used softener sheets, but used sheets are a little easier to handle.

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Posted by riogrande5761 on Tuesday, August 2, 2016 7:43 AM

carl425

One last thought and then I'm out of ideas... are you pre-wetting the base before applying the brush coat?  The dry plaster underneath will suck the moisture out of the new layer otherwise.

That is a very good point.  I've noticed in areas that had dry plaster cloth as I was laying new wet plaster cloth overlapping dry area, it would indeed suck the moisture right out of the wet plaster cloth and I would need to spray it down to add moisture back and smooth it over to allow the plaster to fill in the voids.  Same would hold true for plaster so Rob's suggestion that the plaster needs to be mixed at half cup plaster to half cube water which is much wetter than the 1 cup plaster : 1/2 cup water plus a tad more that Joe gave.  That would help allow for some of the moisture getting absorbed by the dry plaster cloth it is coating.

 

Some have mentioned Gypsolite.  Gypsolite or something like it, Structolite IIRC, has been mentioned at model train show scenery demonstrations.  That may be something worth looking into if the a thinner plaster or other things do not prove satisfactory.

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Posted by riogrande5761 on Tuesday, August 2, 2016 7:20 AM

wp8thsub
You're running up against a couple issues. One, it sounds like your mixture is too thick for the job you're asking of it. For brush coats I mix plaster about 50:50 with water. Use batches small enough you can apply the whole thing before it sets up.

I was attempting to follow Joe Fugate's guidelines as follows:

"Best approach is to start with a half cup of water and maybe a cup of plaster with the baking powder retarder mixed in. Add the plaster to the water, then add a tiny little bit of water if it's too thick. And I mean tiny - as in a tablespoon or two."

I'm willing to go back and try some more and go thinner toward your half/half suggestion.  Thin plaster might be a bit hard to apply to vertical surfaces.  Joe was suggesting 1 cup plaster to 1/2 cup water and then add a tiny bit as needed.  That seems to be a good deal less than half/half - plaster/water.  I was doing about 1 cup plaster in June before things got to busy for me to work on the layout; is 1 cup plaster a small enough batch? 
 

Second, never but never expect brush coats to provide a finished surface. They will always have an unrealistic texture with visible brush marks. Apply a finish coat that's smoothed with your fingers to cover any tool or brush marks. If you can't control the plaster adequately with your fingers, that's where you could try something like drywall mud, but only after the setting type plaster forms a solid base.

Yes, it's very evident that a finish surface isn't possible with one coat which is ok.  I'm guessing two coats is needed, one to cover the paster cloth and hide the shapes of the layers and pieces laid down, and a second to provide a surface finish, whether using a plaster for the second coat or another medium which might be drywall mud.  That second coat only needs to be thick enough to fill in the brush marks etc. to give a sufficient surface as desired.


 

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