Problem With Structolite

I had similar results when using it with paper towel hard shell. I think it's directly related to the solids vs. liquids in the mix. I found that the material that I used first was very wet with a high liquids ratio. As I progressed, the towels selectively absorbed the water out of the mix and the result was the mixture got more solids as I went along. The result was that material hardened poorly with that chalky appearance. It not only looked differently but it was significantly weaker. Keep stirring your mix as you progress. Also watch the water/plaster ratio in the original mix.

Trainman2001. Did the wetter/earlier towels dry set up better or worse than the later/dry/less liquid towels.

It was worse at the end of the batch.

Thanks, I'll go with wetter.

In a scenery how to book I recall a comment that Structolite (or Gypsolite) should not be applied directly over a foam board base as it will not adhere to it.  They recommend covering the Styrofoam with a layer of plaster cloth (or paper towel dipped in Hydrocal) and then apply the Structolite.  To get good adhesion of the Structolite to the plaster cloth base I lightly brush some water over it before spreading the Structolite. Works like a charm. 

Ed Rappe

Thanks Ed, I will give it a try. I was hoping to avoid plaster cloth (cost and mess) but the results sound better.

Structolite rarely dries to a consistent color. But, if you give it a good coat of flat latex house paint, you will seal those slightly chalky areas and produce a consistent color surface for applying washes of color.

I use a tan or a gray latex paint, but white could be used if you want all coloration to be in the form of washes.

To avoid the whitishness, apply a thicker layer of Structolite. It usually stays chalky where the layers are thinnest. Structolite over bare foam is OK, again, if the layer of plaster is thick enough. Over 300 lbs of Structolite applied so far over the years, and it is all still intact.

Jim

Thank you Jim I really appreciate the input. I'll be sealing the chalky area with a white primer then washes. Thanks again

Jim,  Beautiful pictures!  How did you apply the structolite over the steep cliffs?  I am applying it over rosin paper and it is running down.   I tried it over another area where I had plaster cloth and it also ran quickly.  Finally it also dried in light and dark gray.  Thanks for all the great info you've posted.

Thanks, guys.

I apply the Structolite with a 2" throwaway paint brush. That way I can stipple the surface with the tip of the brush to give it a rocky texture and avoid tool marks.

For steeper terrain, I use a thicker mix of plaster and keep dabbing to make sure it is adhering. Sometimes you have let a thin coat set up first, then go back and add thickness later.

Jim