Slip must begin dry?

[Rick Wise]

Would someone care to explain why slip recipes  always say to begin with bone dry clay?  Is that somehow better (or the end result different) than using wet clay.  Its as if the instructions for boiling water said "First take some ice cubes ....."

[Hulk]

Good question!

I'm using slip that's just watery body clay that's had the sand and/or grog sieved out. Getting it all blended up from wet clay can be a real pain, for the little blobs of wet clay will retain their dryer core behind a shell of goo for a very long time (Simon says  https://www.youtube.com/watch?v=C2hFwMt2v34 ) - test for yourself, two balls of clay, one dry, one wet, same size, drop them in containers of water ...the dry clay will absorb water and become uniform ooze very quickly.

 

 

[Benzine]

1 hour ago, Rick Wise said:

Would someone care to explain why slip recipes  always say to begin with bone dry clay?  Is that somehow better (or the end result different) than using wet clay.  Its as if the instructions for boiling water said "First take some ice cubes ....."

Is said recipe for a colored or other such decorating slip, where other things are added?

If so, it's so the recipe is precise.  If not, then I have no idea.

[Mark C.]

Are you talking aboiut slip clay for mold work or trailing slips? or somthing else ?

If its slip clay for mold work than its about the weights in recipe and the fact that wet clay vs dry clay hyrates much differently . Its easy for dry clay to accept water its not the same for wet clay to take water.Especially porcelains

which are you talking about ?

[Magnolia Mud Research]

I frequently use moist clay to make decorative slips - especially wet scraps from new clay bodies.  
The procedure: 
put water in a kitchen blender, set speed on medium, add chunks of moist clay to the blender, and blend until the slip is uniform and smooth.  When the slurry gets thick enough, stop the blender, pour the slip into a container, and let the slip age a day or so before it is used.    
My decoration techniques are built on this kind of slip.  The "chunks" are made by cutting slabs of clay with a wire into cubes about the size of a thumbs -- big chunks stall the blender.  
 
The stored slip is deliberately made and stored slightly thicker than intended, unless a lot is to be consumed for that batch. If the slip is too thick for what is needed for decorating a pot, an estimated amount is placed in another container and thinned with water with a whisk or stick blender just like one would do when preparing artist paints on a palette.   

If some of the slips dry with time because the container is not air tight, water is added and blended with a wand blender. 

never had problems with "blobs" from using moist clay bodies.  

I sometimes add "additives" to some of the slip as part of the decoration application.  The additives are mixed with a brush, stick, or palette knife.  The additives can vary from oxides (iron, copper,... ) to crushed bisque ware, another slip, cornmeal, and/or chopped pine needles.  Commercial low-fire clay bodies are also prepared this way to produce decorative slips for cone 10 stoneware and porcelain.  

This method of making and handling slips evolved from ignoring the textbook (because books were hours away) and using the materials and tools in the shop and trying something when the need appeared.  Yes, the mixtures were tested on pieces that would protect the kiln and the surrounding ware.  Application seems to be more important to successful results than the procedure of making the slips.  

N.B. I expect a decorative treatment to only be "decorative" and certainly not a specific color or appearance; Each use is expected to produce a surprise.  Often, the surprise is that the appearance is very close to the appearance of last use of the slip.  In other words, the slips have never failed to do the job. Using a red clay body slip for decoration on a dark stoneware clay body is pilot error not the fault of the procedure or the materials.   

LT

[oldlady]

so you can repeat something you like.   if you start with 200 grams of dry clay and mix 20 grams of a stain, oxide or carbonate and you like the result, you can repeat it next time.   it is simply easier to add water and measured colorant to a known weight of dry clay. let it slake overnight and mix it well before using.

if you do not care how the color comes out each time, mix it wet with something and see what happens.