If you live in an area anything like mine, you have plenty of clay “soil” and hate it. It is terrible for gardening and makes a huge mess when the kids play in it. However, clay is an ingredient in cob, which is an amazing natural building material used for all sorts of things. I have plenty of projects to do this year that I can incorporate cob into. But before you can make cob, you need to gather up all the clay. I have plenty of clay that will be very easy to harvest, but if you don’t there are still ways to collect clay. Check out the links at the bottom.
First, dig off the topsoil until you find a pocket of clay. Dig the clay and sift out the rocks. I used a grill grate for the big stuff. The rocks I pick out go in a bucket for use as gravel later.
If you are doing fine work, a top coat, or any finish work, you will want to sift finer. I used a plant tray. Some of these “rocks” are actually wet clay clumps. They break apart if you rub them through the “sifter.”
There are much nicer sifters that you can make or buy. These were free and quick.
Then do a soil test, to find out the specific clay mixture you have.
Fill a jar about 1/3 full of the soil you want to use. Fill it up, almost to the top with water. Shake it up really well.
Let it settle for about 24 hours, but you should start to see the sand settle out in 10 minutes.
You can see the sand settled to the bottom, then a silty layer, then clay. My soil is mostly sand and clay.
There are different ratios of sand and clay that you need depending on what you are building. I’m working on a cob oven. I use a more clay rich mix with added straw for the base and a sandier mix for any part of the oven that gets really hot.
Clay and cob are also great buildings materials to use when you have kids who want to help. After my kids saw how I was using the clay, they not only wanted to help, they started building their own projects.
Projects using the clay we gathered, coming soon!
For more information, check out these links: