Advice needed for concrete forms for decorative items.

I plan to make raised gardens and numerous planters, etc, out of concrete.

I will be pouring mostly into plywood forms making the various slabs. Where my problem lies is adding the decorative bits that will imprint into the concrete face. I considered using sawdust and Titebond three but I can't scrounge up enough fine sawdust for the purpose. Paper mache would be great but I have to make it water proof. It needs to stick to the plywood through at less 12 poring. I doubt even oiling it would work. How to make paper mache waterproof?

And other suggestion appreciated but I would like to avoid commercial products.

Also anyone know of good books on the subject. I love the idea of creating with concrete.

Reply to
Gino
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Commercial form liners meant for reuse are usually made of heavy latex rubber. Even they probably cannot make 12 pours.

Flat plywood with no decoration might be hard pressed to make 12 pours.

Formed concrete requires vibration to get good detail from formed decoration and even just good flat walls.

Vibrated concrete gets a tenacious hold of forms. It is not rare to splinter out cast in reglets and end forms.

I think your efforts will be better spent at finding a way to repeat your decoration with no plans of reuse.

To aid in removing the concrete from the forms without damage to the concrete, cast in details can be greased, varnished, waxed, or treated similarly. Cast in items also need draft (they need to be tapered, I have found that the degree of taper needs to approach 5 degrees) There is nothing worse than having a nicely cast reglet that you cannot remove without chipping or marring the finish concrete.

Hope some of this helps.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing . . . . DanG (remove the sevens) snipped-for-privacy@7cox.net

Reply to
DanG

I have made 100 ft of 6" curbing in a single 5 ft trough made of greased plywood. The form is still in excellent shape. I soaked it in vegetable oil.

For my smaller stuff I have had good results pouring on sawhorses and banging the underside with a hammer while toweling it in. I use a strong mix but wet with various scrap metals for addition strength.

I'm only looking to do simple shapes not fine detailed finishes. Geometric patterns have been easy using wood strips but I would like to make more organic patterns. Sawdust works well but I just don't have enough of it. Even if it breaks off into the concrete it's easily removed and repaired in the mold.

It would cost me more in plywood than it would cost to build out of treated wood. I need 100 square feet of 14"high x 8'long 2 inch thick walls. They do not have to be perfect. They will all be painted. I just wanted a freeform pattern on the face.

Thanks for the advice.

Reply to
Gino

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