Concrete Mold Making - Other Crafts

AA Aaron's Akua Member Rancho Santa Margarita, CA Joined: Jul 09, 2004 Posts: 1596	AA Aaron's Akua Posted posted on Thu, Dec 1, 2005 8:55 PM Silverline & Gigantalope, After reading that website step-by-step, I realized that there's lots of methods for this type of thing. Here's a quick recap of the method that seems best for say 2 foot or larger tikis: Seal the piece. There are many sealers, but shellac seems to be the easiest and cheapest to me (besides I've got plenty on hand). Apply the mold release. Apply around 4 coats of brush-on polyurethane rubber over the piece, building it up to about 3/8" thick. Use a marker to pre plan where the splits in the mold will need to be be when the mold is removed and apply "border" lines accordingly. Use modelling clay to set up little "walls" (for lack of a better word) along the "borders" where the splits in the mold will occur. Apply the "mother cast" over the polyurethane mold for strength. You can either use a special casting product or plaster and burlap. Do one of the sections up to the modelling clay walls, let it dry. Remove the modeling clay, apply vaseline to the dried edges of the piece you just cast, then cast the next section right up to it. 8 ) When all the sections are cast over, use a mallet and screwdriver to split them along the border lines and remove the mother cast. Use a razor/knife to cut open the polyurethane mold (careful where the seam goes), and take off the mold. When ready to pour concrete, put all of the pieces back together (polyurethane mold back inside of the mother cast), spray/brush mold release on the inside of the mold. Use straps, bungees, etc. to hold it all tight together. Then pour the concrete, let it cure, and remove the mold. This is all from researching the web, and I might have missed a thing or two, but that's the general gist of it as far as I can tell. If anyone has some more tips I'd love to hear them. The "smooth-on" website also has a step-by-step video for $20 that is probably well worth the money. Tyger Jimmy, Thanks for the offer! I will call you tomorrow at lunch if you don't mind. I will do a step-by-step on this once I get it started. It may be a while, though. Cheers, Aaron

Silverline & Gigantalope,

After reading that website step-by-step, I realized that there's lots of methods for this type of thing. Here's a quick recap of the method that seems best for say 2 foot or larger tikis:

Seal the piece. There are many sealers, but shellac seems to be the easiest and cheapest to me (besides I've got plenty on hand).
Apply the mold release.
Apply around 4 coats of brush-on polyurethane rubber over the piece, building it up to about 3/8" thick.
Use a marker to pre plan where the splits in the mold will need to be be when the mold is removed and apply "border" lines accordingly.
Use modelling clay to set up little "walls" (for lack of a better word) along the "borders" where the splits in the mold will occur.
Apply the "mother cast" over the polyurethane mold for strength. You can either use a special casting product or plaster and burlap. Do one of the sections up to the modelling clay walls, let it dry.
Remove the modeling clay, apply vaseline to the dried edges of the piece you just cast, then cast the next section right up to it.
8 ) When all the sections are cast over, use a mallet and screwdriver to split them along the border lines and remove the mother cast.
Use a razor/knife to cut open the polyurethane mold (careful where the seam goes), and take off the mold.
When ready to pour concrete, put all of the pieces back together (polyurethane mold back inside of the mother cast), spray/brush mold release on the inside of the mold. Use straps, bungees, etc. to hold it all tight together. Then pour the concrete, let it cure, and remove the mold.

This is all from researching the web, and I might have missed a thing or two, but that's the general gist of it as far as I can tell. If anyone has some more tips I'd love to hear them.

The "smooth-on" website also has a step-by-step video for $20 that is probably well worth the money.

Tyger Jimmy,

Thanks for the offer! I will call you tomorrow at lunch if you don't mind.

I will do a step-by-step on this once I get it started. It may be a while, though.

Cheers,

Aaron

Post #201145 by Aaron's Akua on Thu, Dec 1, 2005 8:55 PM