mark, look into the way they make concrete counter tops some use formers
with all the detail in place like split pvc tubing and plugs through the
concrete to make mounting holes for fixtures to the concrete. The molds
can be a negative like the way the caps were problem made.the form
should be very slick like melemain (sp). use wire mesh and or rebar
like in any concrete work for strength. this is a touch on how the
system can work. There are books and info on the web and your local big
box home inprovment stores.
hope this helps with an ideas.
Charles The LURKER :)
I could tell you how to make that as a concrete cap, but I'm not sure
that it is concrete. There appear to be seams in odd locations for a
concrete (seamless) pour. Are you sure it's not a built-up limestone
I certainly agree w/ Bob M that it surely looks cast and not poured in
But, I couldn't even decide for certain it's really concrete although I
finally decided maybe it was from the last picture in which I decided
the markings in the side _might_ be some small air pockets or gravel.
Some of the pictures looked like it was actually a granite or similar
stone (I don't think limestone, too much "figure"), and there was the
one with what appeared to be either a form mark or perhaps a seam???
So much variability in lighting and contrast from one to the other left
me wondering just what I really was seeing and not at all sure about
the actual material. But, I'm virtually positive with the others it
wasn't poured in place but something either cast or cut.
Most definatly concrete. the smoothness is achieved by a combination of
vibrating the form and the actual form itself. This can eaisly be
reproduced using trim moulding (for the edges)and dimentional boards
2x4's or whatever thickness is necessary once made the whole thing must
be caulked and painted (for the smoothness) spraying the forms with a
dishsoap solution (dawn and water) or straight diesel will keep the
forms clean and should be good to do several casts. Another option is
to line the form with painters plastic ( the real real thin stuff)
before pouring this will produce a irregular texture pattern.
I agree, definitely cast, no trowel touched that piece especially on
the edge profiles.
We have cast cap stones similar to this on a few occasions. Our
technique is much like you have posted. Formwork, caulk,
paint/sand/paint/sand etc. We use an SDS hammer and an old chisel with
the end cut off and a crutch tip over the end to vibrate. We set the
form on thin piece of foam rubber, hold the hammer against the form and
hammer a bit.
If I were going to make several making a master out of hydrocal or some
other very fine plaster and then a latex mold from that master would be
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