That depends on your location. Both of the Walmart Super Centers in my town have Plaster of Paris. Something like $4.97 for a 5 lb pail. Also the Lowes/Home Depot/Menards have Sheetrock brand patching plaster(20-200 minute drying time variations) in 18 lb bags. This stuff sells for about $7 to $11/bag, depending where you get it. It mixes like Plaster of Paris, and you can get different drying times. I have been using the 90 minute stuff; you get about 60 minutes of 'working' time, and it is 'sandable'. I mix cheap acrylic paints(Walmart/Hobby Lobby/Michaels) in it to make 'ground goop'.
Jim Bernier
Modeling BNSF and Milwaukee Road in SW Wisconsin
If it's been sealed off pretty well from moisture, it should be fine.
Why not just do a small test casting and find out? Keep us posted.
It takes an iron man to play with a toy iron horse.
Has anyone done side-by-side comparison tests of the various casting materials? I'd be interested in seeing if one or the other produces a more detailed casting. I've always used Hydrocal for my castings, so I don't have anything to compare it against.
Thanks for any info.
Darrell,
I use regular Plaster of Paris in all of my Woodland Scenics rock molds. The 'rocks' take stains much better than the super hard Hydrocal. I use Hydrocal to 'paint' my medical 'plaster cloth' hills so that they are very solid. I then add my rocks and fill in with a sloppy mix of 90 minute sheetrock plaster. It as a working time of about 60 minutes and dries to a 'sandable' finish. It takes stains very well, and you can even mix cheap acrlyic paints(Walmart or Hobby Lobby) into the 'soup' to pre- tint it. I have been using this as an alternative to 'ground goop' for my scenery.
If you bought the plaster mix at your (not so) LHS, it is probably molding plaster, aka plaster of paris. Using it in your molds will be almost the same as using Hydrocal, but the rocks will be softer and somewhat more fragile. The other difference is that your plaster will wick up more water than hydrocal would when it comes time to add more moldings or other scenic materials.
If you're happy with the results of this batch, you can buy plaster of paris at your local home improvement center - big bag, not too expensive. Hydrocal is much less common, but not unknown.
Chuck (modeling Central Japan in September, 1964)
Sure! Go ahead and use the plaster. While plaster of paris isn't quite as hard as hydrocal, it works well for rock molds. Hobby-sized tubs are available at Wal-Mart. Pick up some water-based tubes of paint while you're there. The paint can be used to tint the plaster as you mix it. I usually use a brown or black to tint my rock moldings. If the molding gets chipped on the layout, it won't show a big bright white spot!
Have fun, and remember, drop cloths are your best friend! LOL
Darrell, quiet...for now