Post #676627 by Gwen on Sat, May 4, 2013 6:42 PM

Hi Lori! I am tickled to see that you did it! Looks good. Yes, any concrete mixture with sand will start to set up in hours- I was just doing one today (see my lamp thread for). Three parts sand to one part portland cement makes a dandy carving mix.
Should you at some point want to do one that dries slowly and gives you time to work in detail, you can try 3 parts vermiculite to one part portland cement. It costs a lot more, because vermiculite is pricey in large quantities, but it is the Rolls Royce of concrete for carving. I wish I could buy it in serious bulk.
If you lash a rope around your tube before pouring in the concrete, it will stay together. Also, if you want to keep the tube from moisture damage so that it can be used more than once, you can make a big tube from plastic sheeting and line your cardboard with that. I have used the same tube repeatedly now.