Hydrocal vs Plaster of Paris vs Sculptamold?

[hawk4117]

Hello all,
Just got my train tunnel portal mnt. all plaster clothed up and now I'm ready to add some rock outcroppings before painting, and was wondering what would be recommended to adhere the rock cropping's to the mnt. side.  I'm actually using tree bark for the rock outcroppings. There's also a Sculptamold product I've seen used, but not sure which one would be better.  Any suggestions?  Thanks!

[jonathan]

I made rock croppings from molds with hydrocal, and secured them with caulk.  Then sculpted a little spackle around the cracks and painted.

Regards,

Jonathan

[hawk4117]

I've seen videos of hydrocal being used for that but when I saw how realistic tree bark can be and saw a few videos, I experimented with them.  It makes cool rocks when painted the right way by dry brushing different layers of grey and lighter colors. They also can be used for outcroppings. I might just give hydrocal a try.

[Len]

Hydrocal works better for molds than Plaster of Paris. It's relatively "softer", making it easier to carve, and Plaster of Paris gets a sheen when molded. Plaster of Paris will also wear out your carving tools real quick. For covering large areas Plaster of Paris is fine though, but it doesn't take stains too well once set.

A trick I've used is mixing drywall mud (not spackle) with brown or grey, depending on the terrain, Tempera paint powder. Then coating the plaster with the paint & drywall mud mixture, no more than 1/4 inch thick. This establishes a base color for later scenicing. And doesn't give you a bright white spot if there's a chip at some later time. The problem with spackle is it drys too fast, and gives almost no working time.

Never tried SculptaMold, so can't say anything one way or the other about it.

Len

[hawk4117]

Thnx Len! I'm going with Hydrocal for placing the rock croppings.  I'm going to use painters putty for the gaps.  Thanks for the advise.

[rogertra]

All the magazine articles, every one of them, recommends Hydrocal for castings.

Cheers

Roger T.

[Woody Elmore]

I made the mistake of adding a colorant, used by professionals who install walks and the like, to hydrocal - the hydrocal crumbled.  What worked was painting on the ground color after the hydrocal has set. I was surprised at how much of a color solution was needed. The hydrocal is like a sponge.

A buddy of mine who was into On3 said he was going to model the SPNG in the Owens valley - nothing but desert!

Scenery was never my strong suit - good luck to anybody out there playing with soupy plaster!

[Len]

Colorants for concrete have things in them that don't play well with plaster or hydrocal.

For rock outcrops and such, I use very dilute Woodland Scenics colors, or acrylic water colors that have been thinned way down, applied to the surface.

Tempera powder works well for coloring drywall mud for surfacing large areas of Plaster of Paris, which is stronger than the mud for base coating.

Len

[hawk4117]

After more research on all three of these products I found that what I actually need to set my rock cropping's (tree bark) on the side of my tunnel is sculptamold, where I cannot find anywhere.  It used to be sold by Woodland Scenics, but not anymore..can't find it at Michaels or any other craft stores.  The only place was online at Amazon.com so I orders a 3lb bag.  Hydrocal is best for castings as mentioned, but sculptamold is not...It has cellulose bits and easier to work with in sculpting on top of plaster cloth or plain plaster.  It has a little longer working time too before drying and you can add color to it.

[Len]

The non-Woodland Scenics verson of SculptaMold is also known as "CelluClay". Both "CelluClay" and "ScultaMold" are available in larger quantities, and cheaper, than Woodland Scenics.

Len

[hawk4117]

The brand name for the 'current' sculptamold is AMACO.  I did a search on sculptamold alternatives and did notice celluclay, so I called both my local craft stores and they did not carry it.  I think their brand name is Activa? Now I just have to wait a few days until I get my bag of sculptamold, so my tunnel will just have to wait! lol

[mabloodhound]

Hawk, I think the PofP would have worked but the sculptamold should do fine.  Caulk would also work as all your trying to do is attach the bark to the already formed hill/mountain (not making a mold).
Good luck as this is a good technique.

[hawk4117]

Thank ya hound...appreciate all the advice..I used plaster cloth on two shoeboxes with paper and the tunnel came out awesome.  I mixed up P of P to brush over it to strengthen it a bit more. Yes I'm not making rock molds as my croppings are tree bark...a little kept secret that thank god finally came out, because I didn't want to spend too much on molds and hydrocal. At first I was going to try hydrocal , but that's really for rock molds as most modelers have recommended. Tree bark for rock croppings are awesome!  

[Len]

Actually, Hydrocal mixed just a tad thinner than for casting outcrops makes a decent 'goop' for attaching things to a plaster or Hydrocal surface.

Len