David, I think you're talking about styrene boards. I've been using the styrofoam boards with the little beads that are very good at embedding themselves in cement mixtures. I cut little wedges from styrofoam to insert in the block forms to make blocks that will go around a curve. You're being preposterous but I refuse to be insulted. I never said my blocks were anything but simple blocks. They have a poured footing and are mortared together with gravel behind them. I didn't say they were strong; matter of fact, I didn't make any claims except that I had made a lot of them. Like I said, I'm sorry for hurting your feelings. My concern was genuine, even if you feel it was misplaced. Peace? Deb

I make my gritty medium mix in about 2 gallon increments, so mixing can occur with a kitchen utensil. I use either 2,4, or 5 gallon buckets. If I had to make large batches, I'd probably fill a 55 gallon drum, cover it, and roll it around. I could also enlist my husband to build/weld a frame for turning it. That wouldn't be too difficult, I imagine. He's very handy. For medium sized batches, I'll probably just use a baby pool and my little estate shovel... or use the tarp method Al suggests. It shouldn't be too strenuous to mix an average sized batch.

We use a wide variety of commercial releases but for old concrete you can try this homebrew combination. First, seal the surface if possible. It will keep anything from penetrating and forming a bond. The best choice depends on the nature of the piece and whether or not it must remain "as is". If yes, then seal with something that will be removeable and will not permenently affect the surface. Painting on liquid soap or a light wax for example. These can always be removed later with water or alcohol. If not, then a more aggresive release like oil, Pam, Shellac, etc. (these penetrate concrete and will be there for a long time as well as altering the appearance of the original). Once you have applied a sealant, one of the best releases for POP is a very fine coating of a dry powder...baby powder works great. Dust it all over while the sealant is damp or tacky and it will form a lightly bonded layer that very little will ever stick to. It also leaves the POP mold clean on the inside, where oil alone can impart and leave a layer inside the mold that never quite sets properly and may lose a lot of detail by coming off when the original is removed. Take a look at the Reynold Advanced Materials page on the link below. They have a lot of different releases for different situations and are great people to go to for advice. They are really knowledgable and helpful. Even put on hands on" seminars at their locations. Hope this helps, best of luck and let us know how it turns out. Here is a link that might be useful: Molding & Casting Supplies & Info...

What chowdhry is referring to is more of a dryer mix of the concrete. Certainly not wetter otherwise the mix would collapse if you remove them from the tins. However I am concerned about using tins. Often tins have these lips on the rims and so the opening is slightly smaller than the insides which would cause problems when removing the concrete. You might get a brick too large to be removed. So watch out for those kinds of rim. Also, I've seen cement stick to tins so releasing the brick can be problematic unless you line the tin with plastic but then that leaves a lot of lines from the folds of the plastics. With milk cartons you get thicker bricks and essentially using up more concrete. So there's the disadvantage of using the form. More concrete in one form - less bricks you can make. However if you don't need a lot it's still a good way to go. I believe there is something that's used - a spray to help release the concrete from the mold - it's used to 'grease' the mold before the concrete is poured in. Ask the hardware store about this. And Sheryl is right about concrete curing - having done hypertufa myself. YOu need a curing period with plastic on the top to help get the concrete to fully cure otherwise - you get cracks. Chowdhury described in her first response, a technique I've used to make my concrete materials - and it's something I would recommend. Build the mold out of 2x4 - no top nor bottom, and with a flat surface covered in plastic, you can easily make bricks and remove the mold as soon as the brick has hardened a bit. And cover with plastic to prevent fast drying. - The advantage is that you can easily remove the material and you may need less concrete to make the bricks. - And it's a technique still in use in countries that make mud bricks for houses. I digress with this other thing technique I made some years before. I did the same thing as Chowdhury descriged, making a square mold with 2x2 and then I poured very smooth sand in the bottom and then I got my daughter to put in her footprint indentation. And then I poured the concrete mixture into it. Only my mixture was a wetter kind in order for the concrete to fill in the all the spaces. I had a relief of her footprint. The other thing I did was to put in seashell indentations and once again I got seas shells out of this technique. What's more the sand gave a nice texture to the block. Might be a something you can do at some point. anyhow, good luck on your experimentations.