Modeling sandstone blocks?

[Ray Dunakin]

I'm trying to figure out a way to model (in 1/24th scale) a building made of sandstone blocks, such as this:



I was thinking I could just make a few dozen thin "blocks", make a rubber mold, than cast as many as I need and glue them to a substrate. All well and good in theory but so far I haven't been able to make any master blocks that have the correct texture.

First I tried peeling the paper off some foam core board, and carving it to shape. This turns out to be way too time consuming, produces blocks that are not consistent enough in shape, and the texture is overly coarse.

Then I tried carving some from balsa rectangles. The block shape is consistent but the texture is all wrong. I can't get the face to look like broken stone.

So, I'm open to suggestions/advice. How would you do it? Has anyone else here ever modeled something like this?

[Lawton Maner]

In an early issue of Mainline Modeler Jack Work did a step by step tutorial of making cut stone blocks like the ones you are looking for.  Later on in Mainline Modeler CC Crow carried the technique forward and built a number of HO scale models using cut stone blocks.  If I can find my file folder on plaster working, I'll post the exact publication dates later.

The basic technique is to first make blocks the sizes of your stones out of plastic or some other material (you only need one of each size), make a rubber mould so you can make enough blocks to get a supply of blanks.  Then cast the blanks from Duram's Rock Hard Putty: http://www.waterputty.com/ (which as I understand is a mixture of wood flour and gypsum plaster).  Once you have enough blanks, you score around the blank a couple of scale inches below the front face of the block, and then chip away the putty until you have a face which resembles a cut stone block.  You will only need 50 - 60 finished blocks as you can then make a second rubber mould and cast stones to your heart's content.

If you are working in a large enough scale and want a different looking stone, these guys sell a large number of moulds to gamers for their fantasy games:
http://www.hirstarts.com/index.html

[Lawton Maner]

As promised, the Mainline Modeler article by Jack Work was published in the January/February 1980 issue.  CC Crow's articles appeared from 1983 through 1994 at more or less random intervals.  Hope this helps.

[marc_reusser]

I recall aome years back, reading a method for making stone blocks in this surface style, using Bondo, layed out on a wrinkled piece of heavy foil. IIRC foil was wrinkled/wadded as needed (the wrinkled surface will be the texture for the stone face), then Bondo was applied to a needed thickness (think it can be layered) adross the foil...when dry, was cut into the varying width strips needed for the block sizes/course sizes, these strips were then cut again, perpendicular, to make the block widths. These were then assembled/glued onto a backing/form/building wll shape in the pattern needed nd then grouted...i think with spackle.

I don't know how well wrinled foil hols up to the pressure of applying putty, but I think this idea/approach could also be done using plater, hydrocal or durhams, by laying the foil sheet into a say 12x12 form of the needed depth, pouring in the plaster...cutting the blocks as per above, then doing any surfce rework along the cut edges as/if neede to give a more hand chiseled look.

EDIT:  ....on second thought...on the bondo approch, maybe the bondo was smoothed out on a wax paper surface, and then the wringled foil pressed into it from above, while still soft.

If you awnt the commercial vendor approch, maybe try giving New England Brownstone a call.....they do stellar castings, and my have.....or be willing to do....some 1/24 patterns.

[granitechops]

Ray, is this too rough?

Acheived by laying building wall flat, cutting stone shapes out of thick card 1.5mm, & applying mix of Acrylic/fine sand/ filler (Spackle?)/white wood glue & water to a thick consistancy, & stippling mix to card shapes glued to wall  which held mix to shape while dried.
Maybe you could do same to flat strips & use them to do some castings?
I used random stone shapes, but would also work with more regular block shapes

Edit;   the dressed corner stones were done with same mix, but applied in a thinner layer & brushed out horizontally with a coarse paint brush

[eTraxx]

A couple of In-Progress shots of my coke oven bank 'stone'. The stone is Sculpey .. textured with a piece of red lava rock

[mabloodhound]

Marc's comments are my thoughts also.   Use Sculpy or POP for the blocks and put it down in a sheet.   Roll up a ball of crinkled foil and roll it over the entire sheet.   Then cut out the blocks when dry and arrange them in a random patter to make your mold from.

[5thwheel]

Pour plaster of Paris in a flat dish or something like that.  When completely dry, snap it into pieces like you would do with peanut brittle.  This will give you several pieces with rough edges like broken sand stone. You can stack several together to make a thicker piece.  Glue them together to form a block and then shape to the shape of the block wanted.  Adjust the face texture at the seams and then carve into a block.  Make several of these of various sizes. Make little cardboard trays for molds, lay a bit of modeling clay in the bottom and set the block on one side down so that the clay holds it in place.  Mix up several very small batches of Durham with a little bit of color in them.  Pour the Durham in several different colors to form layers. Some you can give a light stir with a toothpick.  When dry this will give you a sand stone block with different colors in it.  You only need about five different blocks. When you lay them you can flip some over to give the texture from a different angle. The variations in the layers will also give a different look to several blocks made from the same mold.

[marc_reusser]

Dave's input makes me think, that you coudl use DAS air drying modeling clay as well, to press the foil into. Dick Blick carries it....and I think Michae'ls may as well.

[darrylhuffman]

Bill Hudson's technique should give you want you want but I would add one more step.

After snapping the plaster to get the rough edges, I would then wet the blocks and give them a quick scrub with a stiff paint brush to knock off the really sharp bumps in the plaster.

This would give a look more like the blocks were brought from the quarry and then cleaned up a little by the builder for a slightly smoother look.

[Lawton Maner]

You can roll any of the acrylic clays that harden in the oven in your kitchen out onto a natural stone surface which is rough enough to your eye for your scale, bake them and then score and snap them into pieces small enough to make the stones.  A piece of slate works well in HO, if rough enough also in 1:48, split sandstone might work in larger scales.  If you take a hint from baking cookies and use a dowel of appropriate size at each end of the rolling pin, the clay will be a uniform thickness from one side to the other. Just don't get caught using She Who Must Be Obeyed's best rolling pin.

[Ray Dunakin]

Thanks for the tips, lots of good ideas here. I actually came up with something else last night that looks like it will work, but I can use some of these other techniques too.