Concrete molds?

[jymbee]

I'd like to experiment making such things as small sitting benches, table tops, etc. using concrete. Anyone have experience with using concrete molds sold for this purpose?

 

[rockshaft]

I've never used a pre-made mold, but I made a mold out of melamine for my countertop project.

 

[/pine]

I'd like to experiment making such things as small sitting benches, table tops, etc. using concrete. Anyone have experience with using concrete molds sold for this purpose?

I've made a few using basically and sand box...if you are going to cast items exposed to the elements and you are going to mix your own concrete be sure to use an "air entraining" agent to prevent freeze-thaw fractures etc...

 

[jymbee]

I've never used a pre-made mold, but I made a mold out of melamine for my countertop project.

Very impressive! What techniques did you use to come up with what appears to be a pretty unique surface??

 

[jymbee]

I've made a few using basically and sand box...if you are going to cast items exposed to the elements and you are going to mix your own concrete be sure to use an "air entraining" agent to prevent freeze-thaw fractures etc...

Thanks-- good advice. Not quite sure what you're describing with "sand box". (?)

 

[rockshaft]

There are countless cool things you can do with a mold. In this case, i applied some glass fragments to look like red salmon, and after the mold came off i ground the surface away to expose the aggregate stones. There is also some blue pigment that i added to the mix.

 

[forgeblast]

I have border ones an stepping stone molds i bought off ebay, The plastic versions will last a while but not for a long time I normally duct tape the mold before I use to to make it last longer. Its better to get the thickest mold that you can. I keep a can of spray oil (cooking ie pam) to spray the mold and then pour in.

 

[/pine]

Thanks-- good advice. Not quite sure what you're describing with "sand box". (?)

There are lots of variations...you can Google the terms...here is a basic idea...

How to Make Concrete & Cement Molds | eHow.com

 

[tcartwri]

Important to use a vibrator to get the air out of the mold. You can use anything really. ( insert joke here ) Just place it against the mold after you have poured, and have a little bit extra ready to pour in when the air escapes.

 

[Pete Judd]

I used a plastic mold to make a patio years ago. One bag to each mold, and it worked. Now it is under another 3 feet of earth. But I have made a couple of molds using hardwood with waxed paper on the inside of the mold to make it realease, Hinges on the corners.

 

[KretZ]

I used a plastic mold to make a patio years ago. One bag to each mold, and it worked. Now it is under another 3 feet of earth. But I have made a couple of molds using hardwood with waxed paper on the inside of the mold to make it realease, Hinges on the corners.

I am in the process of making a patio like what you describe. I had to stop when the weather got too cold to pour. Why is yours under three feet of earth now?

 

[Ed of all trades]

With many molds you need to use a release agent, so it won't stick to the mold. you might get away with it and then again you might. If you don't you just ruined a good mold. Tapping with a rubber mallet works well on many molds to release air.