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How can I create a mold for a large concrete pot ( greater than 1.5 by 1.5 metres) ? Answered

I wanted to have series of pots next to a deck . Rather than just square,I wanted to have something like half a sphere drawn up; maybe a better way to describe it is a cone with the point cut off and inverted. I could make an internal mold with heaped wet sand , but how can I mold the walls for consistent thickness, reinforcerd with wire and asmooth exterior The problem is to create a pourable mold in an interesting shape.


What you are asking sounds like a job for "ferrocement", which is ideal for thin shells like you want to make. Ferrocement is placed by hand and smoothed with a float. Making a half sphere in damp sand is a good idea. Make simple depth gauge to measure the thickness as you make it by pushing a blunt dowel into the wet cement.

http://www.ferrocement.com/ has some stuff on the techniques and results.


9 years ago

you could cover one of those exercise balls then deflate it when the cement is cured.

That's very big. You could dig a big hole in the ground and line it with plastic sheet, but you'd have a job getting the things out again. A lot of work with wood and thin ply' may be the best practical answer if not the easiest.
See what Thinkenstein does with cement - might help.