Mixing cement to sculpt

Question

I'd like to try sculpting. Concrete (like quickrete) seems to be a real inexpensive medium to experiment with. I'm going to use hammer and chisel.

What aggregates do i need to add to the cement to make it suitable to carve on?

Answer 1

I have tried, experimentally, a mixture of Portland Cement and Powdered Limestone.

Unfortunately, I don't remember the exact ratio, I think it was 3 or 4 parts limestone to 1 part Portland cement.

Also, it was most carvable 12 to 18 hours after pouring.

(I am not sure if "carvable" is a word?)

After a day, the material had gotten extremely hard, and I couldn't carve it.

Answer 2

There are two types of sculpting. Subtraction: removing material to get the object desired and addition: adding material to get the object desired.

I helped make a sculpture using cement. A frame (super structure—skeleton) was built and the cement was layered over it. (Addition method)

What you want to do is to pour cement into a form and make a sculpture using the subtraction method. You could do this but I think it would be a lot of extra work. Mix up the cement using sand and no rocks. Make a form  (box) and pour the cement into it. Let it cure enough to remove it. Then allow the cement to dry completely. It will be super hard and ready to subtract the material needed to reveal the object you see. Be sure to observe all safety guidelines. Wear eye protection and an air filter mask. Do not breathe the dust. Don't hit your thumb.

Good luck and always:

Keep Arting!

Jeff (weseye) Wesley

2D & 3D artist

Answer 3

Another option to consider is aerated concrete construction blocks  Trade name hebel  can work with  woodworking tools (old ones) and then render. Lightweight and easy to work  same dust health concern.

As to the concrete the rule is the faster it sets the less strength it will have so quikcrete if it rapid-setting not a good idea especially if your going to be hitting it. Hitting any fresh concrete not really a good idea but cutting with diamond blade saw disc or angle grinder though messy better option or wait for a month to it fully hardens then bash to ya hearts content.

As to the aggregates anything, however keep your finish in mind, hard to  get a crushed brick to a polish but the effect is nice, don't add anything harder than the finished concrete as that's making your carving even harder to do so no quartz! To get a stronger concrete though something absorbent helps and wet it well before incorporating into mix. I have used burnt nails from waste wood, charcoal from fire ashes, paper pulp and waste glass and brick. The harder aggregates though were used with one piece waste plaster molds, that is in solid clay make sculpture coat with plaster remove clay add concrete mix remove plaster.  

Answer 4

Why don't you try soapstone.  it is inexpensive and easy to begin sculpting with.  Around me you can buy it at a few places.  But try an art catalog (on line) like d**k Blick.