So having recently attended Paul Smith's primitive pottery day I have had my attempt at a primitive pottery firing and in the natural order of curiosity I decided to test the clay content of some soil.
To add some context, I took along some mud from a site near some football pitches where I used to play, having remembered that the mud used to stick in clumps to my boots, for Paul to have a look at.
He said it had some clay-like qualities but also had some impurities in too so out of interest I decided to refine some. I weighed the wet soil and it was just a shade over 400g, I thought it would be interesting to see a before and after figure.
I added the mud to a 5 litre plastic bottle with the top removed and then tipped in around 1.5 litres of boiled and slightly cooled water. I agitated the mud to get it in suspension and then left it to settle to see how much sediment was made out of curiosity.
This mixture was then sieved into a bowl and the shot in the top right shows the detritous, sand etc that was removed. You can sieve the mix straight after it's sieved but as I'd allowed it to settle I had to rinse the cut down bottle with the dirty water a couple of times to get it all out.
And without further ado I tipped the refined mixture into an old pillowcase to seperate the water from the clay mixture. good job it was an old one as it has taken on a brown hue after a wash...
The pillow case was suspended with paracord on my washing line to catch the filtered water and I'm glad I did as there was a fair bit of what I could only assume to be very fine clay particles. I tried and impromptu sieving session through a coffee filter but it still ran through.
I left the bag dripping overnight and indeed I had a decent looking blob of clay (is there a specific term?) but we'd had a slightly windy night and I decided that the blob was a little on the dry side. So how did I soften it up? By carefully draining the already drained water from the bowl and adding the super-fine clay to the mix. Running a finger through the top of the blob left a smooth indent so as far as I was concerned, job done.
And so how much did this final finished article weight? A tad over 200g so it had almost literally halved in weight. I'm sure I can find a purer source but it was useful to know what I had not far from me.
Finally here's a Youtube video of the process and of a primitive pottery day I attended a few weeks previous to this.