More millstones and info
As I promised, here's more photos.
I experimented with buff, red and black concrete colorant and added perlite to the dark grey stone to give it a flecked appearance.
The round stone with the sprinkler head in the center opening was my first one. I kept tripping over the head and decided I needed something to make me step up and over the sprinkler. I eventually settled on a millstone.
I checked real and cast ones online and after recovering from "sticker shock" decided that I could make my own. I decided some millstone research online,interesting topic BTW, and finally figured out what to use to cast and carve it. Little did I know that this would be such an addictive and rewarding project!
The first photo is of one of the pans I use to form the stones. I have two pans, they're both the same so I'm just showing one. The white gizmo on the chair at the bottom of the pan is the hose/drain attachment that comes with the pan, sometimes it's attached, sometimes not. If it's attached it's easy enough to remove. If you look in the middle right portion of the pan's rim you can see where I've used duct tape to cover the attachment hole. I've learned to cover the hole both inside and out otherwise you have a nice round bump on the cast stone. I also very lightly wipe the inside of the pan with petroleum grease before use. I use the $store version of Vaseline. You don't have to grease it every time, just often enough to keep that icky-kinda-sticky feel.
Making a millstone is a two day project. You need two back-to-back days to mold and carve a stone. After carving, the stones need to cure for a least a week before moving. It is also a heavy project. Please get or have help the first time you unmold one of these puppies and definitely have help moving it initially. After the stone is completely cured,several weeks, you can just roll it around but until then handle it gently.
Decide what pattern you want and have it worked out in your mind, on a piece of paper or somewhere, preferably before mixing the mortar. Once you start carving it's hard to change the design.
I've found that it takes one regular bag of mortar mix per stone. One bag will overfill the pan a little so I've either made small stepping stones to go under pots(I have a deviled egg platter that works really well for this!) or just left it a little over full.
Allow the mortar to set for 24 hours, then having your carving tools gathered, CAREFULLY unmold the stone and CARVE IT IMMEDIATELY!!!!! This is the voice of experience speaking here.
Realize that whatever tools you use to carve your stone will be very abused by the process. Don't use good tools, pick up old ones at thrift stores or wherever. I now have a "set" of tools I use for nothing but millstones. Also PLEASE PLEASE PLEASE wear leather gloves and eye protection when carving! Wearing a long sleeved shirt is also a good idea.
I think this covers the topic. If not please let me know!