I use plaster cloth and use a 3" wide paint brush dipped in water to activate the plaster. Then, I cover it with a thin layer of plaster of Paris.
Marlon
See pictures of the Clinton-Golden Valley RR
Down here in Florida we cannot ever find Homasote or Hydrocal.
.
I have used plaster of paris on every layout I have built and had no problems.
When I was casting building sections with Hirst Arts molds, I used dental plaster.
-Kevin
Living the dream.
The Activa brand is basically the same stuff they make/made casts out of and what has been adapted to the hobby. You get a whole lot more and it's more economical, and much less messy.
Even using it to finish drywall, once it sets for good, it doesn't reactivate with water. If it did, it would make drywall finishing mistakes easy to fix, without sanding. If that was the case, painting a finished wall with latex paint would soften the mud, and it doesn't.
t's Generally true but I have had the mud come up if painting and getting it too wet for too long. I did quite a bit of replacing drywall and mudding/taping in my last basement and am presently drywalling 700 sq ft in my current basement. Generally you are ok but it can soften and come up if it is wetted and gone over too many times with a roller. It happened to me.
For my last layout I did use drywall mud on luan for a river bed, per Rob Spanglers methods. Here it is before scenery was built around it:
And after.
I put a fairly thick layer of regular plaster of Paris over the plaster cloth but I found the plaster cloth was like a sponge sucking lots of moisture from the plaster so you do need to wet it with a spray bottle so the plaster retains the moisture you mixed into it. Here is the plaster coating while the river bed was masked off:
Riverbed bottom painted and ready for simulated water.
Rio Grande. The Action Road - Focus 1977-1983
The stuff Jim talks about seems like it's worth checking into.
The wife brought me some material they use in her office for making cast, just a small piece to try, but I'm sure that would cost a ton, and not everyone would have access to it.
I don't have a hardshell scenery base, so, for what I used the drywall mud for, it worked fine, and it has not softened when it got wet.
I used it for paved areas, and I used it as it was intended, to coat drywall, for my bridge and retaining wall work, to simulate poured concrete, with no problems.
Because of it's tendency to crack when applied too thick, it's probably not the BEST product for a hardshell finish.
Mike.
My You Tube
I suggested using a cheaper version of the plaster cloth sold by Woodland Scenics or Scenic Express. You can buy a big roll of Activa - same stuff, for about 40% of the cost of the above. I used a paint roller pan with water to dip it in and lay it on the surface:
I wouldn't use drywall mud, either, as it will re-soften if it gets wet, as in adding ground cover, ballasting, etc.
I've not used it for dipping paper towels, but Durabond can be mixed to just about any consistency and will set in approximately the time shown on the package. It's available in several setting times. I use Durabond 90 (sets in approximately 90 minutes) for my plaster-over-screen landforms. It dries very hard and won't re-soften when you're adding scenery. It can also be used to represent water and is good for casting purposes, too.
Wayne
Sheffield Pottery in Sheffield, MA ships three or four grades of genuine hydrocal and ultracal, and other casting materials as well. A 50-pound bag of Ultracal 30 is about $30, but it costs about $30 to ship it. If you live nearby, great; if you don't live nearby, not great, but still not too horribly bad. Plaster of Paris costs a little less and is available at all the big box stores and craft shops.
Hydrocal 30 is literally three or four times as strong and a lot harder than plaster of Paris. Which is good. Or not. Finished plaster is a lot easier to carve and sculpt using gouges and chisels.
I don't know about using either hydrocal or lightweight hydrocal or hydrocal 20 or hydrocal 30 or Ultracal or plaster of Paris with gauze cloth. But I've used all the above for rock casting, and as I prepared the solutions, I never noticed any significantly different handling characteristics. Hydrocal gives you a little more working time and a lot more ultimate strength, but they should all work perfectly well to soak up the gauze.
All things considered, I'd go with the PP. It's cheaper and easier to get.
Only my opinion, of course. Good luck.
Robert
LINK to SNSR Blog
iawesternWhere does one find the larger bags of normal hydrocal? Am not having luck with the big box stores in the area (menards, lowes, home depot).
Maybe it is only distributed to certain stores but I'm on my third, 25 lb. bag of this Plaster of Paris that my Home Depot carries here in Ohio.
https://tinyurl.com/y9qg4uby
Sometimes the people in the stores are not familiar with their own stock. Perhaps you can order this and have it shipped to your store?
I use this for both casting and for forming hard-shell scenery. Seems to work well for me. You can slow down the cure time with a little vinegar* with the cold water. Always add the plaster to the water not the other way round.
*Some suggest baking powder.
Good Luck, Ed
I would use Durabond if it is available locally. Exterior grade spackle is a good durable product, but I believe it only comes mixed in a tub, ready to use. You'd have to spread it like icing.
Look for hydrocal at the plaster and lath building supply store (not the chains). There is usually one in most larger cities. It is still used in houses to repair plaster walls depending on the area....
I don’t recommend drywall mud as it doesn’t set up as strong as hydrocal. I like the rock-like harness of hydrocal for the basic hard shell layers as it creates a bullet proof base. Plaster does absorb water over time and will lose the ability to set up to full strength. I end up buying new bags after a few years as the old ones go bad. How quickly this happens is somewhat dependent on the humidity level of your area.
I would recommend casting plaster if you cant find hydrocal but I don’t recommend plaster of Paris as it doesn’t reach the strength of hydrocal or casting plaster.
Opinions will vary on this – good luck with the search,
Guy
see stuff at: the Willoughby Line Site
You may want to try pacon craft cloth at Amazon.com It is the same stuff as the Woodland Scenics stuff but comes in a big box. Search for craft cloth and it will come up. I use plaster of paris. I mix up some in a coolwhip tub. More than that it ngets hard so mix up a small batch.
I'd give the drywall mud a chance if it was mine. I've used it for a variety of things on the layout. Maybe just try a small area and see how it works.
You could buy a small tub of the powder, or the premixed, and give it a try. You can also get it with different set times. I think the quickest is 15 min. from mixed to hard.
Drywall mud used in too thick of a layer, all at once, will tend to shrink and crack as it dries, but has a thin mixture for dipping papper towel, it should be ok.
If it does end up with cracks, they will be very fine, and a thin layer, applied after the first has completely dried, will cover it up.
I don't know where you could get actual hydrocal, maybe a store for artist and sculptors?
I don't have any advice on ultracal. If they call it hydrocal, maybe you bought some old stock. Unlikely they are manufacturing their own plaster. You can buy 25# of hydrocal from some guy on ebay who calls himself Plaster Guys or you can ask US Gypsum who sells it in your area.
https://www.usg.com/content/usgcom/en/resource-center/tools/where-to-buy.html
My experience with joint compound is it cracks and is no where near as strong.
I'm a recent convert to sculptamold. Not something you can dip paper towels into, but it is lighter and less messy. It molds ok, but not as sharp as hydrocal, the fibers tend to be visible.
Henry
COB Potomac & Northern
Shenandoah Valley
Greetings. My topic here is about dipping paper towel strips in a hydrocal solution for a scenery base, NOT for casting rocks and molds, etc.
I purchased a 50 lb bag about 20 years ago and split it with another modeler at the time (he passed away several years ago). I ran out recently and couldn't find another big bag, and then purchased the ultracal 30 hydrocal from scenic express. Big disappointment. This stuff does not work at all like the normal hydrocal. I believe the stuff from scenic express is made only for casting - nothing else.
Where does one find the larger bags of normal hydrocal? Am not having luck with the big box stores in the area (menards, lowes, home depot).
What other substitute would work? I see the stuff on ebay, but am afraid of what it might be.
Would ready made joint compound mud mixed with more water work?
Thanks in advance.
Mark