WHAT'S THE DIFFERENCE BETWEEN USING PLASTER OF PARIS INSTEAD OF HYDRACAL

[kewatin]

Because i am 140 miles from nearest hobby shop it is impractical to drive this distance  to purchase, where as locally i can purchase a 5 lb box of plaster -paris for $4.99. what results can i expect using the plaster -paris over the lite weight hydracal.  any different mold prep and i have feeling the castings using the plaster-paris will in all probability be not as strong,but i am between a rock &a hard place. any suggestions or comments will be greatly appreciated.
regards&later KEWATIN

[JerryB]

Hydrocal is much stronger than plaster of paris. It also takes lots more detail, and most of all does not 'slough off' like plaster of paris. That is important for a long life scenery base.

The sloughing of plaster results in lots of dust and chips on a continuous basis. Sealing plaster of paris can  help, but most sealers causes the plaster to have a sheen, do not take stains, and it still does not make the finished scenery any stronger or damage resistant.

You can order Hydrocal on-line. Here is a link to the Google results for Hydrocal on-line vendors:

http://www.google.com/products/catalog?client=safari&rls=en&q=hydrocal&oe=UTF-8&um=1&ie=UTF-8&tbm=shop&cid=18341465073687993943

There is a wide range of prices, taxes and delivery charges, but some of them are quite reasonable.

BTW, I would first check with a local home improvement store or any business selling Gypsum products. That includes commercial building suppliers and folks doing casting of garden statuary. While the Woodland Scenics Lightweight Hydrocal is an excellent product, it is sold in really small packages at a high price. Purchasing a larger quantity such as a 25 or 40 pound bag from a local store (rather than a hobby shop) is much more cost effective, and you will still have the benefits of Hydrocal over plaster of paris. Just a little heavier, but really not a problem unless you are planning a layout that is going to be moved frequently.

Hope this helps.

Happy RRing,

Jerry

[Desertdweller]

Think of the difference between chalk and marble.

Les

[Jerrys HO]

I use plaster of paris and  have no problems. I have used hydrocal in the past but when you have a large mountain it can get costly. Both do an excellent job.
As far as plaster of paris not taking stains I do not find it any different than hydrocal.

Jerry

[NarrowMinded]

I have used both, I like Hydrocal better.

I noticed that when freehanding plaster of paris it stains just about the same, when I cast plaster of paris in molds it takes stains different then Hydrocal, it seems like the smoothness in the surface causes  the difference, but nothing a little more stain here and there wont cure.

NM-Jeff

[Jim Banner]

I use them both, Hydrocal for mouldings, plaster of Paris for about everything else.  But a dollar a pound is a bit much.  Try your local drywall dealer.  Mine sells 50 pound bags for $20 (about 40¢ a pound.)

If you want something with even less sheen, try surfacing your plaster with drywall compound.  You can cover large areas at once and carve it dry.  But is does not like washes of colours diluted with water.  But air brushed artists' acrylics diluted with water of windshield washer antifreeze are fine.  Drywall compound is also good for transitions under track.  You can trowel it to approximate shape with a putty knife or just a piece of plastic.  After it dries, it is easy to sand down the high spots and fill any low spots with a bit more compound.  Just don't put on too thick a layer at once or it will shrink and crack.  About 1/4" maximum and let it dry overnight before adding the next layer.  Drywall compound also sticks well to other materials.  Drywall compound, also known as drywall mud and drywall joint filler is NOT the same a Spackle used by painters.  Spackle sets quickly and very hard - drywall compound dries slowly and is soft enough to sand.

Jim

[Doneldon]

kewatin-

You've received some good advice here. I'll endorse the use of drywall mud (best) and Hydrocal (next best) over plaster. Plaster sets very hard so it's both brittle (prone to chip easily) and hard to tool after it sets, which is pretty fast. You can buy drywall mud already mixed in five-gallon pails but you'll be paying for shipping all of that water to your source. Dry material you mix yourself is a little less convenient but a lot cheaper.

You can add dry colorants or latex paint to your mixture so your material will have a base color. This can save putting on a first base color coat and can make the inevitable damage less noticeable.
                                                             -- D

[mabloodhound]

You mentioned molds so I guess that's where your concern is.   I would check at a local drywall or lumber company for the hydrocal.   It is really a better product.
Also, take a look at this video as there are some good casting tips: http://www.youtube.com/watch?v=A7G88lyWTUs

[kewatin]

To all whom have responded, a great big thank you.good information and i will try casting my molds with plaster-paris first to see the outcome.i have also used drywall mud,especially on my woodlan scenics inclines &it worked out very well with miminal sanding to give a smooth surface. i am using &carving foam and will attach my various rock mold castings with liquid nails and then brush drywall compound on every thing,then paint with a latex brown paint before airbrushing the final colours.
I can't give enough thanks to all those whom responded.
REGARDS&LATER  KEWATIN