Applying Hydrocal rock faces to plaster cloth layout

[Anonymous]

Since the backs of the rock castings are flat, what is the best way to attach them to the plaster cloth scenery and still look good?Theres no way they are going to fit flush due to scenery contours.


Thanks

Jared

[jwmurrayjr]

Jared,

One way is to "butter" the backs of the castings with thick plaster and stick them to the hardshell. Spray both with water first.

Some folks use hot glue and then fill in the gaps with plaster.

Both methods will probably require a little "touch up" around the edges with more plaster.

[Anonymous]

Ok thanks, makes sense I was just curious about the asthetics but with addtional plaster and some ground cover it will look ok I think


Jared

[bogp40]

Jared,
One way to have the rock castings fit uneven plastered areas is to apply the freshly poured mold directly to the area. When the Hydrocal just starts to harden, but still flexable, butter the prewetted spot w/ some fresh plaster and place the mold. hold firmly pressing to the shape of the scenery. Many times the casting will fracture especially over very convex areas. The mold will feel warm as curing takes place. After a minute or two you can let go. Leave the mold on until completely hard (5-10 min), then carefully peel the mold back- if edges still crumble give more time. One disadvantage to this method is that you have to know the mold for shape and strata orientation. I generally keep a sample casting numbered to the coresponding mold w/ an arrow indicating top. After placing mold next to mold the more difficult thing is to arrange pieces as the fillins. For solid rock cuts there is no other way other than carving because the mold method will have the patchwork quilt look- If the cut is small enough grass small trees/ bushes placed between castings is very convincing. One other thing you may want to try is coloring/ dying the plaster as you mix. I have found the dry masonry dyes to work excellent, the product is formulated exclusively for concrete or mortor and has no affect on the properties of hydrocal , or plaster.
Another note, the buttered mold sticks to extruded foam also- when dry it takes a hammer and chisel to remove. So plastercloth is not always nec. unless over wire screen.
Bob K.

[TBat55]

I use construction adhesive that comes in caulk tubes (about $1.60/tube).
I also put a chunk of styrofoam in the mold after it's poured. This saves Hydrocal. After it's dry you can remove the styrofoam leaving a cavity in the back of the rock casting. The result is a casting that weighs a little less, costs a little less, and has something for the glue (or plaster) to grab on to.

[bogp40]

TBat55,
Great idea for those large or deep molds. have to give it a try.
Bob K.