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Alternatives to plaster to coat plaster cloth

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Alternatives to plaster to coat plaster cloth
Posted by riogrande5761 on Monday, August 1, 2016 1:30 PM

I have given ordinary plaster a try as a coating over plaster cloth and found it set too fast, was difficult to control and didn't care for the surface I got.  I'm wondering if there are any recommendations for alternatives?

One example I thought I saw somewhere was someone using drywall mud.  This actually sounds attractive since you can buy it already mixed and since I have worked with it to put up drywall, it does seem like it would be easier to work with and smooth and not set up so darn fast as plaster does.

Has anyone worked with drywall mud in this way; other alternatives to suggest?

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Posted by BATMAN on Monday, August 1, 2016 1:49 PM

Drywall mud will crack and crumble unless applied in thin coats. Someone suggested Durams Water Puddy once for thicker applications. I am not sure how thick as I have not used it myself. 

I have had the same issue wanting to change a plaster cloth spot on the layout by building it up slightly. I ended up cutting very thin slices of foam with a bread knife and hot gluing it down, I then used Dap to hide the seams.

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Posted by UNCLEBUTCH on Monday, August 1, 2016 2:02 PM

all I use is drywall mud.Just spread it on , in my case over carved foam, use a wet paint brush to smoth/shape. Can be carved after it starts to set or after it gets hard.Use craft paint to tint color.

It will crack if too thick,but ez to fix, and some cracks look like they belong there.

I've used it to landscape,hills ditch banks,roads sidewalks concreat walls and steps,loadingdocks ect. I tryed grade crossing, it will work but take a little messing with, ther are better ways

Its cheap, I think less mess then plaster,if it gets away on you ,setting too fast just sprinkle a little water .  try it

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

Thin coats are all I need, unless you mean paper thin.  But rather than go waste money on something thats not going to work, I'm soliciting idea's for something other than plaster.  I did try mixing in baking powder but the plaster still seemed to set up too darn fast.  It's a bit fussy to try to slather on to hill sides and then smooth it down before it's set up.  I tried using a paint brush but the plaster had bristle marks.  I really want a smoother surface - some of the vertical parts will be, as geologists call it, "massive" standstone.  In otherwords not layered but smooth.

On another forum, one guy said he used something called CelluClay which is offered on Amazon by Activa, the same brand that I got the 5 pound rolls of plaster cloth from.  I do like the idea of something like drywall mud; something of that texture might be fairly easy to apply and smooth with a putty knife.

I've already got most of the basic land form shapes using the cardboard strips and plaster cloth so I don't need any foam - just something to coat the plaster cloth to give a smooth surface and hide the plaster cloth.

Uncle Butch, I did have a spray bottle and did try spring water on the plaster to smooth it - that helps a little but ultimately the bulk of it is setting up and then funs over, it's too late.  Spraying water isn't really enough.  I need a layer somewhere from 1/8th to 1/4 inch thick to cover the plaster cloth, mostly 1/8th inch should do it - even less in on some parts.

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Posted by HO-Velo on Monday, August 1, 2016 2:17 PM

Tried drywall mud and Like Batman said, put it on too thick and it cracks big time.  Have used Sculptamold for smaller areas, works well and with a slower setting time than plaster, but costs more $.  Have yet to try, but there are a lot of "ground goop" recipes out there that sound interesting.  Mike Confalone uses a mixture of Celluclay, H2O and latex paint to make his "mud" and appears to have a long working time.

good luck, Peter

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Posted by riogrande5761 on Monday, August 1, 2016 2:31 PM

Sounds like drywall mud is off the menu assuming what I'm describing is "too thick".  I have a couple 3 lb bags of Sculptamold but was thinking I'd save it for other purposes rather than a broad coating of the plaster cloth.

Someone mentioned Mike Calaphone's video's for mud but to see those isn't that a pay service?  Besides, it the CelluClay is a good medium, and it is easier to work with, that may be a viable alternative to plaster if it can be be applied with a smooth texture; longer working time is a big plus.

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Posted by BATMAN on Monday, August 1, 2016 3:03 PM

Search "ground goop"  it might do the trick. It has been discussed on this forum before. 

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Posted by GP-9_Man11786 on Monday, August 1, 2016 3:11 PM

I've heard adding viniger to plaster will slow the curing time. I'm just not sure how much you would add.

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Posted by CandOsteam on Monday, August 1, 2016 3:23 PM

riogrande5761

I have given ordinary plaster a try as a coating over plaster cloth and found it set too fast, was difficult to control and didn't care for the surface I got.  I'm wondering if there are any recommendations for alternatives?

One example I thought I saw somewhere was someone using drywall mud.  This actually sounds attractive since you can buy it already mixed and since I have worked with it to put up drywall, it does seem like it would be easier to work with and smooth and not set up so darn fast as plaster does.

Has anyone worked with drywall mud in this way; other alternatives to suggest?

 

Riogrande5761,

I have not tried drywall mud, but can suggest Sculptamold.  I love this stuff because the texture can be determined by how much water you add and how much you "fold" it with a spatula.  Less water and less folding over (like making bread dough), the rougher/more granular the texture.  Slightly more water and more mixing gives a very smooth texture.  I use water temperature to control setting time.  The colder the water, the slower it takes to set.  I normally go with warm water and it takes about 5-10 to set firm and overnight to completely dry.

I also use an artist palatet knife to apply the Sculptamold to get very fine control to get thin layers or to add a glob to sculpt into rock formation.

I use 1:1 diluted earth colored flat latex house paint to brush paint the sculptamold.  I usually wait until it dries overnight, but I can also paint 20 minutes after application.  Not a problem if you are in a hurry.

The best part for me is that Sculptamold is 99% mess free.  No nasty drips everywhere and cleanup is a snap with water.

I have this thing about messiness, so I was very happy to find a great way to scenic without any plaster.

If you are interested, I can post in-progress pictures of my approach.

Hope this helps. Big Smile

 

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Posted by UNCLEBUTCH on Monday, August 1, 2016 3:46 PM

riogrande5761
I did have a spray bottle and did try spring water on the plaster to smooth it - that helps a little but ultimately the bulk of it is setting up and then funs over, it's too late. Sprayi

DWmud and plaster are two different animals; I know I can wet "dry"mud and get it workable again, once plaster sets your done.

Couldn't you go with 2or3 layers of mud to reduce cracking ?

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Posted by mlehman on Monday, August 1, 2016 4:09 PM

Careful layering the mud or be sure and use the lightweight stuff, as it can get heavy fast.

Well, Joel went over similar ground I've been over before on Sculptamold.

I'll just add this time that I've also used Celluclay and find Sculptamold generally to be far superior in all around ease of use, workability, and versatility. Where you might find Celluclay better is for those long talus slopes as it can be smoothed a little more easily  for what you're trying to achieve there.

Sculptamold leaves a bit of an oatmeal texture that can be dealt with if you need really smooth, but can take some fussier work and rework. I could take some closeup picks of the results to show as examples. One place that is more 2D is here, where I used gritty texture paint over Sculptamold, another solution to consider in getting those slopes looking right.

In my case these are mostly verticale and yours are much more realistically shaped slopes, but it would look better with more slope to tell you the truth.

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Posted by cowman on Monday, August 1, 2016 4:47 PM

I have seen several articles on "Glueshell" using white glue and paper towels.  I would think that if your plaster cloth is already in place, you could just spread undiluted glue over it with a brush.  If you don't have the cloth in place, paper towels dipped in glue would work in its place.  Not sure what grade of paper towel works best.  I have some strong ones I got for nothing, so no need to experiment with store brands.

The one thing I have heard against glueshell is if you live in a very humid climate it may soften occasionally.

Though we usually think of larger quantites being less expensive, a couple of years ago at Wal-Marts Back to School sale, the 4oz bottles of Elmers was cheaper by the ounce than it was in gallon jugs.  The other advantage was, once emptied, the smaller bottles can be used for dribbling varying strengths of glue/water mix for scenic work.

Good luck,

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Posted by dominic c on Monday, August 1, 2016 5:04 PM

riogrande5761
I have given ordinary plaster a try as a coating over plaster cloth and found it set too fast, was difficult to control and didn't care for the surface I got.  I'm wondering if there are any recommendations for alternatives?

You know what might work? Smooth-it from Woodland Scenics. The stuff for building road surfaces? It's very light plaster. I think much lighter than hydracol and other products mentioned. I would mix 1.5 :1 or 2:1. 

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Posted by carl425 on Monday, August 1, 2016 5:04 PM

Before you give up on the plaster, it sounds like you are mixing it thick and trying to spread it on.  What we did back in the hardshell days, which I think would also be good here, is to mix the plaster about the consistency of pancake batter and paint it on with a brush.

I think you may have a problem trying to spread anything like Sculptamold on a first coat of plaster cloth as it would be easy to break through.

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Posted by Doughless on Monday, August 1, 2016 5:31 PM

Yes.  With the situation OP describes, I would apply any material with a brush.  If its thick enough to apply with a knife, I think that's too thick for bare plaster cloth.  And using a brush will work smoother and faster, and dry faster, allowing multiple coats to not take a lot of time.  Then finish with a knife, perhaps mud, to smooth out the brush marks if there still are any.

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Posted by jack308gtsi on Monday, August 1, 2016 5:43 PM

Plastercloth then Gypsolite. A Dave Frary trick. I love this stuff plus it give "tooth" to the terrain.                   

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Posted by riogrande5761 on Monday, August 1, 2016 7:01 PM

Fyi, I did try to mix my plaster to be like pancake batter and painted it on with a brush.  It set too fast and it hardened with brush streak.

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Posted by Doughless on Monday, August 1, 2016 7:31 PM

Maybe you can apply drywall mud with a knife to fill in or smooth out the plaster brush marks.  As another has said, you can use water, a wet brush or knife, to keep the mud soft and smooth enough to work with it a while.

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Posted by mlehman on Monday, August 1, 2016 7:33 PM

Doughless
Yes. With the situation OP describes, I would apply any material with a brush. If its thick enough to apply with a knife, I think that's too thick for bare plaster cloth. And using a brush will work smoother and faster, and dry faster,

Mostly, I mix Sculptamold at the dry end of the scale, because that shortens drying time and limits moisture working it's way into other stuff. But mix it wet enough and you could use a brush to apply. If wetter mix, longer to dry, but that's the only issue I've noted. Personally, I'd still gently use a blade, but you'd have to be careful not to punch through the plaster gauze.

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Posted by mlehman on Monday, August 1, 2016 8:19 PM

Something else occured to me. It sounds like the idea is to brush whatever it is on in vertical fashion. It might work better to start at the bottom with thin horizontal layers, letting each dry in turn as it builds towards the top. That way the entire span of the plaster cloth is not under stress all at once, but little by little. After that is accomplished, the go back over the base with the vertical strokes needed to achieve the long gritty slope. Since these will have a solid base underneath, this should make it easier to form and fashion these as desired.

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Posted by wp8thsub on Monday, August 1, 2016 9:18 PM
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.

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.

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Posted by carl425 on Monday, August 1, 2016 9:55 PM

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.

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Posted by doctorwayne on Monday, August 1, 2016 10:35 PM

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.

 
Carl makes a good point, but I'd also suggest that you try Durabond patching plaster instead of regular plaster or drywall mud.  
I use Durabond 90 for my plaster-on-screen landforms, and mix it stiff enough that it can be applied using a drywall knife.  However, for your needs, I'd suggest mixing it to a slurry-like consistency, then apply it using a suitably-sized brush.  It will still harden in the specified time, and will not crack whether spread thinly with a brush or 2" thick with a trowel.  If brush marks will be an issue for some areas, you may be able to remove them when the plaster begins to set, either with a softer brush dipped in water frequently or by gentle wiping using a well-dampened paper towel.
While I buy my Durabond in 33lb. bags, it's also available in smaller boxes, if you want to experiment.  
You can also sand it, if needs be, but only in the interval between the time which it begins to set and the time that it fully hardens.  Most of my landforms were brushed liberally with water, using a 2" synthetic brush, immediately after the plaster was applied, and the very few brushmarks which resulted are easily covered with ground foam or other groundcover.
 
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Posted by Grampys Trains on Tuesday, August 2, 2016 1:09 AM

 

 

 

 

 

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Posted by mlehman on Tuesday, August 2, 2016 1:38 AM

Grampys,

Gypsolite is a great idea for an additive to Sculptamold. Still strong at a 1:5 ratio is a little suirprising, but it's versatile stuff.

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Posted by Smokey D on Tuesday, August 2, 2016 5:37 AM

I have found putting baking powder into my plaster of paris acts as a retarder giving the mix a longer working life.

By trial & error my ratio is 1 teaspoon baking to 12 teaspoons of plaster of paris .Mix with water until a smooth mix .

I have found using my  hands to apply it to the cloth I get a better finish.

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Posted by NVSRR on Tuesday, August 2, 2016 5:59 AM

I just use ground goop.   Mine has saw dust in place of vermiculite.   A good surface can be worked in at any thickness.  Long working time.

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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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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 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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