What to use as topping on plaster cloth

[rsn48]

I find plaster cloth alone too thin on its own so I've in the past painted on hydrocal.  Now I've used "proven" techniques to slow down hydrocal's "set" but none of them really worked, from adding vinigar to really cold water.  Some one suggested using plaster from the technique of plastering walls that was popular in the past; it has been suggested that this plaster dries strong and has a longer setting time.

Any suggestions?

[alhoop]

Do you use a small wet paint brush to spread the plaster impregnated in the cloth after you have it down
and are you using multiple layers?

I always put down at least three layers for strength and didn't find it necessary to use more plaster
although the last roll of WS PlasterCloth I bought seemed to have about half as much plaster in the cloth as
previous rolls.

AL

[rsn48]

I find the plaster cloth available to use is "watered down."  I worked in three different emergency rooms in my lifetime and the plaster cloth used for casts is much more dense with plaster material.  I've done two but not three layers so maybe I'll give that a try.  The painting on of the hydrocal actually works well except for its set time, meaning you have to clean everything up before you do the next batch, and when you do paint on, you have to work quickly - a slower set time and it would be perfect.

[Bsklarski]

I mix in water based paint with hydrocol before I spread it. I use brown or back. I also use foam for my basic shapes, so the plaster cloth where I use it, rests on top of the foam in most cases.

[bill pearce]

Hydrocal is only one brand from a plaster manufacturer. Others have longer and shorter if possible set times. Check with a supplier that sells the stuff to professional plasterers or the USG website. It is easier and much cheaper to get a 50 lb. bag from a supply house than getting ten 5 pound bags from the hobby store.

[Flagler]

I think a better support structure for the plaster cloth would be a better solution.Foam,covered with cloth

[mmagliaro]

I have had good success slowing down the setting time of Plaster of Paris with Top Job (yes, the liquid household cleaner).

I always theorized that it worked because it contains ammonia, so putting it into the mix shifts the pH, which is
probably key to changing the setting time.  I am not a chemist, so I have no proof of any of this.  It's just a theory.

The only thing I know for sure is that it worked.  If I mixed up a small batch in a bowl, and added 1 or 2 tablespoons
of Top Job, the setting time would be several hours instead of 20-30 minutes.

I did some experiments.
The detergent in the Top Job may also have helped.  I did try other cleaners
that didn't contain ammonia, however, and they didn't help, so I think ammonia was the key.

----------------------------------------------

As for alternatives...  on my current layout, I used plaster cloth in some areas, and after it set (which is very fast),
I mixed up Cell-u-clay, and brushed that over it.  Cell-u-clay is just ready-made paper mache pulp.    It did a great job.
It is extremely strong and light-weight.  It can be rasped, cut, sanded, or painted.  You can poke holes in it to plant trees.

It ain't cheap (about $25 for the larger size bag), but it goes a long way, especially if you are just brushing a thick layer
over plaster cloth or other land forms to smooth them out and give them added strenght and shape.  The setting time on it is extremely slow.  It takes several days to really dry out and get hard.  That may be too much
of a good thing in your quest for something that sets slower, but I am very happy with the results.

[rsn48]

Will Cell -u-clay take rock castings?

I'll search for Top Job, I'm not familiar with it.

[mmagliaro]

Will Cell -u-clay take rock castings?

I'll search for Top Job, I'm not familiar with it.

I have not actually tried that, at least not the way I think you mean, where one pours plaster in a rubber mold,
and then puts it up against the terrain while it's still a little wet, ejects it from the mold onto the terrain, and forms it into place.
But Celluclay remains porous, will absorb water, and is strong after it hardens, so I don't see why that wouldn't work.
On my project, I put a heavy skim of perhaps 1/4" of Durham's Rock Hard Water Putty against the Celluclay to form
a vertical rock cut.  When the Water Putty got hard, I whacked away at it with a hammer and carving tools, and this
all worked fine (i.e. the celluclay didn't collapse or budge behind it).

You can find Top Job in almost any supermarket in the cleaning product aisle.  It worked great on Plaster of Paris.
I don't know what will happen with Hydrocal.  But it's probably worth an experiment to see how it affects the
setting time and the strength.

[rsn48]

How long for Durham's rock putty to set?

[ArtinCA]

Durham's sets in 15-30 minutes. It's a good filler for wood as well.

I've used Spackle and dry wall mud for the plaster layer on the gauze. Both work well for me.

[mmagliaro]

How long for Durham's rock putty to set?

That stuff is fast.  I think 30-60 minutes.  Somewhere in there.  And it really is rock hard.    Literally, I hit it with a hammer
to make some of the cracks in the rock that you see here.  It's great stuff.
Here's how it looked in my rock cut...


Here's how it looks when it's just brushed on, hard, but not carved or painted.

[Specter3]

Sculpt-a-mold. Bags at most big craft stores and larger Hobbytown stores. It's paper mâché with shredded pulp in it. Love the stuff.

[alhoop]

Jim Hediger covers building plaster cloth scenery in his 'Workshop Tips' in Model Railroader - March 2013.
All good info, some of which is covered in this thread. He gives several sources for plaster cloth - I've
only used Woodlands Scenics  and a roll from a craft store. The cloth in that roll was courser than the
cloth in Woodland Scenics brand and would not conform to small variations in scenery because of stiffness.
Woul be interested to know if anyone has tried another brand that is as pliable as the WS.
Al

[wm3798]

Another fan of sculptamold.  Tint it with cheap craft acrylic or mis-mix latex from the paint store.  Easy to work, takes a little time to set, you can squish rock castings (I prefer real rocks) right into it.  Very versatile, and not as messy as hydrocal.







Lee