Thread: Making concrete tombstone molds?

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Thanks for all the ideas!! I love the idea of using clay for epitaphs and cracks! I figured if I put 1/2 pvc for 80% of the stone, it would cut down on the amount of wire I'd need for reinforcement. I'm noodling about a seperate mold for a base or just leaving it as is. I figure it will take me several "recipes" of cement mixtures to get one that works well. I'll put up pictures as things progress. Any more ideas? Keep em coming!!

If the stones look authentic..I may well leave them up year round. My neighbors already think I'm nuts...give em something else to talk about!

I just joined the forum and saw the post on concrete tombstones and had to comment. Having been a concrete finisher for the past 18 years I can offer some insight.

#1. Head down to your local masonry supply house or concrete plant and inquire about "fiber mesh". Fiber mesh is short strands of a sort fiberglass that acts as a reinforcement like wire does. The manufacturer claims using it is as strong as using wire. I can tell you jack hammering fully cured concrete with fiber mesh in it is not an easy task sometimes. Wire and rebar always rust inside the concrete and eventually helps with its decay, since concrete is porous and allows moisture in it. Ever go by a highway project and see green rebar? The rebar has been coated with a special epoxy paint to thwart rusting. With fiber mesh you can get enough to do 10 cubic yards in a large ziplok bag, so storage isn't an issue, and it won't cut you like wire will. It also is mixed right into the concrete mix so there isn't any wire to poke through a spot where it got to close to the edge.

#2 The vermiculite is an excellent idea to make the tombstones lighter!

#3 If you wish to use some of the epoxy coated wire or rebar you can usually get some short peices from a conrete contractor rather easily. One foot pieces and such are rather common laying around. Just go to a concrete supplier for a can of the epoxy spray paint to touch up the ends and any scratches that would allow rusting.


#4. Many places now have foam form materials to achieve the older style concrete forming withouth having to go through messing with wood as well. A good wood to use if doing a lot of concrete forming is a type of plywood called around here "ply-form" It's a special plywood for concrete forming that is impregnated with oil to prevent swelling of the wood and leaving large wood marks., It isn't cheap stuff, but I thought you might be interested to know.

#5. (enviormental people look away) In a pinch you can use old motor oil as a release agent as well sprayed or brushed on. It tends to stain so it may be advantageous to you. (no we don't use that anymore, we use special form release oils) and those special form relase oils----the same results can be acheieved with deisel.

#6 I like the using clay for a way to put "hand carved letters" into concrete. Will have to try that on one of my jobs.

#7 Hinge forms- iI am not sure what shapes you are going for but you can make "hinge forms" that could greatly make it easier to make your headstones. I'll use this for an example- IF you wanted to make a rectangle cut your pieces of wood and instead of nailing or screwing them together, fasten them with hinges that have removable pins. When you are ready to remove the forms, just pull the pin from one hinge,, and the rest can be folded out , and then re folded and pin attached for the next one. You will probably need to screw a piece of wood at an angle across the form to help hold it square until it sets enough.

#8 Different dyes and powders can make for some interesting colors as others have suggested. Try some of the dye powders and sprinkle a thin line of it on the area that will be the face to obtain to possible "veins" as was suggested before. Not sure how this would turn out, as I have not tried it , but the idea sounds like it could work.

#9 I can't think of anything more at the moment except a word of caution. Remember that concrete contains caustic materials. While they are not extremely dangerous, the dust for one is very bad to inhale, so if in mixing you are creating a lot of dust use a dust mask. Concrete burn is also something to avoid. So remember to wash it off your skin promptly.


Hope i didnt overload!

Mike

We used ply wood forms to give curved edges to concrete, it worked quite well.

Come up with a formula as far as spacing for the PVC pipe so that you can use a constant spacing settup for the rebar or supports that go into the ground. As for having the base and the stone as all one piece, I would pprobably go with seperate pieces, that is how most of the actual monument style stones that I have seen were done, from your end of it, having seperate pieces keeps them lighter in weight, easier to move, and if you break a stone or base, you haven't lost the whole thing, you can replace or repair the part that is broken.
I would also put an eye-bolt sticking out of the back of the stones, this would give you a way to lock them down, whether you have a problem with vandals or thieves or not, I don't know, but the bolts help give you a way to tie the stones down against the tipping, theft, etc.

A question for those who have used the vermiculite in cement before, does this stand up over time or moving the stones in and out of storage, settup, etc.?
I know that a lot of gardeners add it into the soil to help keep the soil workable, but it breaks down in the soil. If it started breaking down while in the concrete, wouldn't that be a problem for structural integrety in the stones them selves?
Just curious.

Have yu ever tried a lime mortar, it gives a good colour and texture, although can be difficult to handle.

Annea, how is the lime mortar for curing when it is in larger or thicker pieces, like a tombstone?
Is it brittle or fragile on it's own, or does it need reinforcement (wire, rebar, etc.)?
Could it be used with concrete, maybe a thin layer layed into the molds first, then filling the balance with concrete, pvc, etc.?

You can get an exposed aggregate effect by mixing brown sugar in water. Use a lot of sugar. After your form is filled, brush the mixture onto the surface. The next day you can wash off the slurry to reveal sand and stones just below the surface. It will look weather-worn.

just to make you aware,,, don't mix the sugar mixture INTO the mix. Using it on the outside to create the worn finish is ok. Sugar chemically reacts in masonry and slows down the curing process and weakens it. Thats why using it on the outside is good for creating an exposed aggregate look.

Some concrete crews I've heard will dump a 2 litre bottle of coke into the drum of a concrete truck before pouring to "slow down" the curing process. If you were to pour sugar on wet cement on a corner of a sidewalk, the spot where the sugar layed would stay wet long after the rest of the concrete is hard. Sugar chemically retards the concrete and greatly weakens it by not allowing the curing process to take place as it should. So back to our crew up top and thier bottle of soda. In essence they are making the concrete weaker by upsetting the curing process. The soda isn't a huge amount and the concrete will harden in time, but it will be much weaker.


something fun to try---Take a cup of coffee (black coffee will show best, no cream and sugar) and pour some onto wet concrete. the concrete on top will turn green. I have no knowledge if it adversly affects the strength, but try pouring it on the wet concrete to stain the surface some.


Mike G