Use of chunk charcoal for rocks

[Painter Carver]

I am planning on using chunk charcoal to provide details of rocks in my mountain layout. The question i have pertains to preparation of the charcoal. My plan is to vacuum each piece and then spray it with some type of fixative prior to placing on the layout, which I plan to do using Sculptamold. Is this a good procedure? If so, can anyone recommend what to use for the fixative?

Thanks,

[BroadwayLion]

LION goes out into the fields and collect real ROCKS. You can break them open to give them a fractured look. 100% Natural, no painting or anything. Just feather the rest of you scenery into your rocks.

 

ROAR

[Painter Carver]

Thanks for the idea. However, I do want to use the charcoal because it gives me the type of look that I want for the type of rocks I am trying to simulate. 

BTW, I realize that I should probaly have posted this in the Layout and Layout Building forum. If I can find a way to delete this thread I am going to do so and repost it in that forum.

 

[dknelson]

By charcoal do you mean stuff intended for a grill?  Briquettes? Usually there is a binder that is oily or waxy that would resist paint, glue, etc.  It might even be parafin.  Genuine raw charcoal might work, but also tends to flake away.  I know the charred wood from my fireplace, which I have experimented with, is simply not stabile enough to use.  Unlike genuine charcoal it is formed differently I know.

I think I know the look you are after.  I have seen effective use of busted up ceiling tiles on edge to capture that look as well.   

Dave Nelson

[ACY Tom]

Charcoal is an organic substance. I'm sure the baking process weakens the wood, and that would almost inevitably cause the structure to break down. Painting might help, but I don't think I'd count on it. I like the striated texture of coal, but that has the same problem, since it's also an organic material. So I make rubber molds from large striated pieces of coal, and use them to cast my rocks in plaster. The resultant plaster castings will be exact copies of the look you seek. The plaster is much more stable than the coal or charcoal. If you use a mold in one location, you can often turn it upside down and reuse it nearby for a totally different look. Nobody knows. It can be painted as needed. Also, the rubber molds can be curved to fit a particular location, and you sure can't do that with charcoal or coal. 

Tom

[riogrande5761]

From my geology major days, I remember:

Lignite/brown coal - softest and lowest grade
Sub-bituminous - next up in grade, and harder
Bituminous - harder, shiny, has layers, higher heating value
Anthracite - highest grade, hard and highest grade.

If you are using Antracite, it may be hard enough to make molds from.  If not, maybe seal it with some dilute white glue?

[ACY Tom]

I've been using unsealed semibutuminous coal from the Broad Top coal field. It's somewhere between bituminous and anthracite. There is some flaking when you remove the mold from the coal, but the mold is quite usable. After some surface coal has flaked off a bit more, you can chip the coal surface to reveal a new and different rock face and make another mold from that.

 Tom

[Painter Carver]

Thanks to eveyone for your replies. What I am thinking of using is the real chunk charcoal that is used for the grille but is not the briquettes. In any case, it sounds like what I want to do is problematic  I don’t think that I want to give up on it yet, however, since I prefer to not go the trouble of making rubber molds. 

I think that I will try soaking a piece of the charcoal in a diluted white glue mixture and see what It looks and feels like after it dries.  I will report on what I conclude.

 

 

[BigDaddy]

Jeez you guys aren't fan's of Steve Raichlen's Primal Grill are you? 

Real grillers don't use briquettes.  Grilling over coal?  Something a few people tried several centuries ago and they found it matched Crocodile Dundee's description of eating alligator.  "You can eat it but it tastes like stuff"  There is real natural charcoal available in 10 and 20# bags and it does look like realistic rocks. 

Artists also use charcoal, the hidden meaning is dirty black stuff.  Since you are not modeling the interior of a coal mine, black is not essential.  I'd paint it.  Latex, spray, I'm not sure it would make much difference.  I don't see it breaking down either it's just carbon.