Homemade clay from dirt... lots of sand?

[af2018]

Hello. Im new to the world of pottery, clay, etc. Im experimenting for fun trying to make my own clay from dirt in my yard. I live on 100 acres of clay-rich soil.

I followed all the steps in Youtube videos, straining, screening, letting the dirt settle, repeat over and over. Most recent I let the clay sit in a bucket for a week, poured off the water on top, etc. I then poured it into a towel. When I was done, I had what appears to be clay but there is a lot of grittiness in the hands while molding. 

What am I doing wrong? 

I poured out the last batch in the dirt and I could see 'streams of dark particles' (like when youre at the beach and the sand has those dark patches. Im assuming thats the sand in the clay.

So.... any ideas how to purify my clay?

Thanks!

[liambesaw]

You can sieve it when it's a liquid. 60 mesh should be ok

[af2018]

2 minutes ago, liambesaw said:

You can sieve it when it's a liquid. 60 mesh should be ok

Thanks. So am I correct to say that clay particles are MUCH smaller than sand and dirt?

[liambesaw]

Yes, they are unbelievably small!

[af2018]

41 minutes ago, liambesaw said:

You can sieve it when it's a liquid. 60 mesh should be ok

If I used a 100 mesh (just googled it) would that take out clay particles as well? I want this stuff super pure just to be an over achiever!

[liambesaw]

Eh 80 mesh is probably as small as I'd go, it is what is used for glazes if that's any indication of how small 80 mesh is.  You will have a hard time screening even at 60 mesh, and at 80 mesh it will probably take hours of pushing it through the screen.

[af2018]

18 minutes ago, liambesaw said:

Eh 80 mesh is probably as small as I'd go, it is what is used for glazes if that's any indication of how small 80 mesh is.  You will have a hard time screening even at 60 mesh, and at 80 mesh it will probably take hours of pushing it through the screen.

thanks!

[af2018]

On 6/27/2019 at 3:57 PM, liambesaw said:

Eh 80 mesh is probably as small as I'd go, it is what is used for glazes if that's any indication of how small 80 mesh is.  You will have a hard time screening even at 60 mesh, and at 80 mesh it will probably take hours of pushing it through the screen.

So I bought this on Amazon (1/100" mesh):

https://www.amazon.com/SE-GP2-1100-Patented-Stackable-Sifting/dp/B00BP2I77U/ref=sr_1_3?keywords=100+mesh+screen&qid=1562179315&s=gateway&sr=8-3

I have no clue if 1/100" equals 80 mesh.

I filtered all my sand/clay water through the mesh and ended up with a slury of what appears to be sandy(ish) clay. Do I have to let it dry out some first for it to turn to a clay-like consistency?

Is this mesh not fine enough? THANKS!

I tried to do that 'snake test' making a snake out of it around my finger and it wouldnt hold up.

[liambesaw]

80 mesh is 7 thousandths (0.007) of an inch, I'm pretty sure.  They are fairly cheap from a pottery supply store, around 15 dollars.  Euclids has some around that price, so does my local pottery supply.

[af2018]

On 7/3/2019 at 3:08 PM, liambesaw said:

80 mesh is 7 thousandths (0.007) of an inch, I'm pretty sure.  They are fairly cheap from a pottery supply store, around 15 dollars.  Euclids has some around that price, so does my local pottery supply.

So do you think the 1/100" wasnt fine enough?

[Bill Kielb]

I am not sure this helps but if I go back to my hydraulics and hydrology class (affectionately called dirt class)  sand can be very fine down to 200 mesh but is more common in the 10 to 60 range. Liam’s choice of 60 mesh is pretty close to your 1/100” or 0.98/100 ths.  The 80 mesh is much finer but as you can see clay is way finer and very fine sand does exist. I am not a clay maker but my guess is settling techniques are an important component of removing very fine sands if they exist in your sample.

 

[Magnolia Mud Research]

This is how I process raw clay from my ponds and potholes:  

crush the dirt to pass window screens. 

Mix with water and pour off the suspended clay after the sand settles (which is very fast).  Alternative route is to slowly pour the slurry down a riffle slope which separates the heavy particles from the lighter ones; sorta like panning for gold , the difference being you are throwing the gold away and keeping the clay.  

Let the clay slurry settle for a week or longer and the separate the water from the solids. 

Refuse the water for another batch down the riffle. 

 

[curt]

Some silt in your clay body is tolerable - but probably not more than 10% by weight.  Think of it like grog.  It is not really going to melt in the firing, and will form a large particle aggregate which acts like  gravel does in concrete.

but, I think as Bill said you want way finer size if you are looking for actual clay particles in the classic sense.  Silt - even fine silt - does not behave like clay and is almost impossible to work with.  It just falls apart when you try to work it.  So it cannot make up the majority of your clay body.

Even most Kaolins at 100 or 200 microns are mostly not plastic.  For plasticity and workability you need legitimate clay-sized particles - eg, ball clay or stoneware clay - in the tens of microns particle size.  Think maximum 200 mesh or finer and you will be starting to get there.

OR, you can try to crowbar in some plasticity with small additions of bentonite if you are willing to make this adjustment.  But even that has its limits.

 

[af2018]

Thanks for the answers. So I did what people suggested and I now have a fine layer of (hopefully) clay particles in a bucket. There is three inches of crystal clear water on top which I am about to pour off. I read the next step is to put the clay in a towel to absorb the moisture. I do I know when I took out enough moisture? Feel?