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New to clay harvesting-Need guidance  RSS feed

 
Dar Helwig
Posts: 32
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I've recently learned that you can harvest clay, process it, form and fire it. I am also intested in trying some cob projects. However, my main interest right now is clay. If there is a better forum for this fell free to move this post or tell me where to put it.

I went to the river where I grew up because I remember the river banks full of pure bluish or gray clay. Now, however, the river has been dredged and the findable clay has changed. It is now a grayish or brownish color. Not good with colors. Got some color blind stuff going on. Anyway, the clay comes in a 4 inch band with rotted vegetation above it and coarse gravel below it. And the clay is not very pure.. So I brought home a couple of buckets and strained it through a screen. So far so good. I let it settle and siphoned off the clear water. My problem arises at the point of forming an object from the clay. It is to wet to form. It takes many days to dry enough to get a firm clay from it. I poured some into a 55 gallon plastic barrel which was cut in half length-wise so as to get it more surface area to evaporate. So my question is, what is the proper proceedure to dry the clay. In fact, I would be happy to get advice on the whole process. I will upload some pics if I am able. The 2 cans of sand and gravel are what I removed from about 7 gallons of clay.
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Dar Helwig
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Here is my screening bucket
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Thomas Wright
Posts: 21
Location: Florida and Colorado
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Try hanging a sheet or other cloth over the bucket to let the water strain out.
 
Dar Helwig
Posts: 32
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I tied some up in a sheet tonight and hung it on the deck railing. We'll see what happens. I think I'll have to go find a source of better clay also. I've been reading that sometimes silt fools people into thinking its clay. I have yet to see proof positive that I have good clay. We'll see.
Thanks for replying.
 
Miles Flansburg
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Location: Zones 2-4 Wyoming and 4-5 Colorado
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Dar, in that first photo I see a couple of slabs of rock or concrete to the left. Try putting the wet clay on that and see if the water will evaporate or absorb into the slab.  I used to dry clay on a large block of hard plaster, the plaster would absorb the water out of the clay. As the clay dried, not to much, I could form it into balls and then wrap it in plastic to keep it at the right wetness.
 
Charles Schiavone
Posts: 32
Location: NE corner of Ohio
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I've done a bit of this.
there are 2 main methods that I've used with success. +/- to both

plaster drying tables
**DO NOT USE PLASTER OF PARIS!!!
it's too soft and will get into your clay and wreck what you make.
it is what Lowes/Home Depot sells
you gotta find No 1 Pottery Plaster
try asking at a pottery/clay store near your closest major college campus
for me that is Columbus Clay in (obviously) Columbus OH. I live 200 miles away.
I think a 50# bag was less than $20
it's is worth the shipping cost
follow the mixing directions (water is added per pound of plaster)
this method works quickly and, if left unattended, can rocket your clay back to too stiff overnight.
I put handfuls of gloppy clay on about 2-4" thick.
depending on how fast I will get back to it
the plaster table is best in a sunny well ventilated area so that IT can be dry to start with

the other method is hanging canvas frames
Imagine a window screen turned on it's side, only it's make of canvas.
secure the canvas all the way around a frame
1x4" should do it
sort of like stretching a canvas for a painting.
only you put the super dooper soupy liquid clay slurry into the frames.
this allows a lot of the water to seep out the bottom (at first) and then to dry more slowly by evaporation, much like the plaster
i've seen photos of these frames set in racks, hung under deep eaves on a pottery barn or shed.

Plaster is expensive and heavy but it dries thing out quick
this is best if there is little or no processing needed in terms of particle size in the clay.(how clean it is)

canvas (cotton duck fabric is the good heavy stuff, not thin cotton sheets) is not cheap either $6.00/yrd but not terrible
but the frames are only as heavy as the wood they are made of when empty.
this is a slower process but better if you need to slake the clay down to a slurry to get out all the larger particles.

as for river banks and clay colors:
when it comes to heating clay above 1000 deg C, the end color, most likely won't match the wet one.
my local clay is either blue or yellow
I think it has to do with the oxidation of the iron as it got exposed to water over the eons.
the yellow stuff sits on top of the blew and tends to follow cracks into the blue.
Because I live on Lake Erie, I can see the exposed bluff and exactly how the clay layers stack up for the first 30-50' of our area.
large clearer areas are apparent from the side view, digging down into it and finding a clean area will be some work

on a river though, I would wonder where the clay came from
maybe investigate upstream or uphill from where you are digging for an exposed hillside with no (or very very little) vegetation hanging from it.
once you find the clay source, you can avoid much of the gravel and organics
if not, you are on the right track
just keep going
the clay will tell you what it can do


this can help, once you learn how to use the system and decipher the images
http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm
this can point you to the soil types in your area
USDA put out books by county once upon a time
mine county's Soil Survey was issued in May of 1973
the data haven't changed
the books take a while to get the hang of too.

 
Charles Schiavone
Posts: 32
Location: NE corner of Ohio
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if possible, you should secure the land owner's permission.
if you are gathering clay on public land, I would look into your local land use regulation through your state's Dept of Natural Resources
usually is the amounts are small enough, they don't care what your take of most things
a few bucks of clay won't make or break you
truck loads of clay get noticed

also, all waterways in the US are under the jurisdiction of the US Coast Guard not.
Even in Iowa.
Water is water to them
they are mostly concerned about runoff and pollutants getting into the bigger lakes rivers and oceans
maybe look to their regulations also
that is if you find success and want to exploit it.
digging a big hole on a river bank will push a lot of silt down stream so do think of who you are impacting with your explorations (fish clams frogs et al)
 
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