Pounding Vs. Rolling Slabs

[Biglou13]

what is your opinion on pounding out a slab vs rolling?

 

for hand built, tiles, slabs etc.......

 

i know you get a denser slab.... but is it necessarily better than rolling?

 

i dont own a slab roller.  so when working at home i pound out slab (95%),  then if necessary roll (last 5%) with large pvc  just to even out

 

in the history of pottery the slab roller, is a new comer......

[Bob Coyle]

That is just about what I do. I pound the clay mass down with a rolling pin, turning it over and flipping it 90 degrees each time. Then I use the rolling pin and a set of shims to roll out a uniform thickness... once again flipping it 90 degress after each roll.

 

I have never had any trouble with warping in the pieces I built.

[Pres]

I have done alot of slab/wheel combinations. I have not noticed much difference in cut, rooed or slammed and rolled in costruction. Ithink that laying out on flat surfaces(boards) is very important, along with not allowing them to dry too fast. Tiles are even more important to get layed out flat with a little space, drying slowly. Personnal opinion.

[Wyndham]

We do a lot of slab pieces and slow drying is a big factor. Our drying room has no windows and towels draped over the shelves to keep drafts away.

With the resent rains, it's taking weeks to dry. Humidity is nearly 100%

Wyndham

[DAY]

Every ounce of clay that enters my studio starts its journey at the dual roller drive Bailey. And has for the last quarter century. The tiles are as flat as Olive Oyle.

I am a production artist, so work cannot wait for lovely weather. I use electric heat table. Work goes on in the morning and into the L&L kiln (fast glaze setting) the next day.

[DAY]

 Tiles are even more important to get layed out flat with a little space, drying slowly. Personnal opinion.

When the clay is firm enough to handle they go on newsprint on sheetrock, get 'decorated', get a top layer of newsprint and sheet rock, go on the heat table. After a 'few'- four to twelve- hours I flip the top piece of drywall. It is soaking wet from the moisture drawn out. The tiles are ready to fire when the top board "feels" dry. That top piece of drywall is enough weight to prevent warping. My tiles are 4x4 up to 12x12, 1/2 thick.

[mrpeders]

I have a few questions.  If you use sheetrock to draw moisture out of the clay and keep from warping, doesn't the sheetrock, (I  used cement board) paper cover get soaked and tear?

 

Also, if I am making flat bottom trays with short sides, how should those be dried to prevent warping?  Is the secret in how or how long the slabs are compressed or how long they "sit" before they are assembled into trays?

 

When using sheetrock to dry tiles, how do you dry impressed or raised surfaces?  Doesn't the weight of sheetrock flatten patterns or doesn't the pattern prevent the sheetrock from evenly pressing on the drying clay?

 

Thank you for your help.

[Wyndham]

I visited a potter that used a dehumidifier in the drying room, that seemed to work well for them.

Wyndham

[oldlady]

is there a way to find what i just tried to post and accidentally lost?  typing is such a pain. i just tried to move a sentence and hit the wrong thing. POOF!!

[Benzine]

is there a way to find what i just tried to post and accidentally lost?  typing is such a pain. i just tried to move a sentence and hit the wrong thing. POOF!!

If you are still typing in the "field", you can just use the undo last change command (Cntrl+Z).

[oldlady]

I have a few questions.  If you use sheetrock to draw moisture out of the clay and keep from warping, doesn't the sheetrock, (I  used cement board)WHICH DOES NOT ABSORB MOISTURE, DON'T USE IT FOR THIS PURPOSE. paper cover get soaked and tear?

 

Also, if I am making flat bottom trays with short sides, how should those be dried to prevent warping?  Is the secret in how or how long the slabs are compressed or how long they "sit" before they are assembled into trays?  SEE BELOW

 

When using sheetrock to dry tiles, how do you dry impressed or raised surfaces?  Doesn't the weight of sheetrock flatten patterns or doesn't the pattern prevent the sheetrock from evenly pressing on the drying clay?.....NO.... ASSUMING YOU ARE NOT USING A 4X8 SHEET 5/8 THICK OR STACKING PILES OF SANDWICHED TILES ON TOP OF EACH OTHER.

 

Thank you for your help.

not unless you soak your clay in a gallon of water! or perhaps make something 1/2 inch thick and just leave it for days covered with plastic.  that is asking for trouble.  the moisture in prepared clay will not affect drywall unless you leave it on the same sheet for days and cover it with plastic so the gypsum  cannot draw out moisture.  moisture, not water. the paper cover might wrinkle up but it will eventually dry. just turn it over.  have several sheets of a managable size to move things to.  slide the partially dry work to a new sheet every day until it is dry. and stand the damp pieces somewhere to dry out again. humidity is a problem in some places.

 

i make the exact items you describe and have used drywall sheets as shelves for years without losing one yet.  occasionally someone will get one wet and if i dry it out and find a bit of black mold a wipe with a clorox dipped rag cleans it up.  it works best if you make the tray and then put your work down by slapping it onto the drywall, if the sides fold down run a finger along the folded edge and it will come right back up again. 

 

there are several videos on you tube you should watch.  the one where the square tray is dropped onto the floor is an eye opener.  do not be afraid to texture a piece and make the tray.  you can always put glass marbles inside a sock and leave it as a weight inside a tray as it dries.  

 

stacking a piece of freshly made textured tile on drywall and covering it with another piece of drywall will not flatten the texture unless it has many high points.  JUST DON'T LAYER SEVERAL OF THEM LIKE A PILE OF SANDWICHES.

[oldlady]

thank you benzine!   marvelous to find that i do not have to lose everything.  but, of course, it is now permanently gone.  i have never gotten down the simple moving of a sentence that all of you folks do automatically.

 

the reply i sent just above is not as good as the one i typed first.

[oldlady]

what is your opinion on pounding out a slab vs rolling?

 

POUND ENOUGH CLAY AND YOU WILL HURT YOUR WRISTS.  EVEN WITH A WOODEN POUNDER.  REPEATED MOTIONS ARE KILLERS!

 

this new edit thing is great, i've been trying it out here, can you TELL?

[mrpeders]

Thank you for the info, old lady.  Very helpful and practical.

[DAY]

More on sheetrock, etc:

 

sheetrock/drywall is just a piece of plaster (gypsum) with a paper covering. "Basically" the same stuff we use for molds, etc.

 

I put a piece of newsprint both under and on top of the tile. That allows the clay to move as it shrinks. I cut a 4'x8' sheet of half inch drywall into 24x24 pieces and tape the edges. (Plaster + clay=disaster!)

 

Since I don't do textured/relief tiles, I have no experience with them. I would try newsprint, then a thin piece of foam, then the drywall. Small (6x12) pieces of foam come in the Orton large cone boxes.

[Biglou13]

Day- i use the dry wall method no newspaper, I'm surprised you get dry wall "soaking wet". I'm new to tiles but after tile was sandwiched between dry wall, which was sandwiched between, two ware boards, covered with plastic, then weight places on top,

I've had a slab built plate warp a little but in this case you can't sandwich dry. I've read slow,even and weighted drying is king.

 

I'd like to see photos of your process, I'm interested in your technique , and the going ons of a production potter, also how do you bisque and final fire? Racks, one shelf per tile......?

 

Old lady, - I have access to roller, until recent I've only used roller, I like revisiting primitive ways, I also feel the the pounding, hands on work puts more "soul" in the work.

 

If I write some thing more than a sentence or 2 I usually use a word processing program then cut and paste.... I hate losing my posts....-

 

I'm still interested in what technically is different between rolling and pounding. And if there are tests break stregnth, warping, slumping, cracking...etc

 

I'm loosely hypothesizing that pounding is better because of increased density.

[oldlady]

just thinking about what happens when you pound vs roll..............pounding shocks the particles of clay and smashes water out. ...............  rolling stretches clay and whatever kind of "canvas" removes some water as well.................  hmmmm.......................

[DAY]

@Biglou13:

My drywall gets wet because the heat panels are driving the moisture up and out. Same way steam rises from a pot on the stove.

(Panels are sheetrock with electric wires inside, used mostly in ceilings) That is how I can go from bag of clay to kiln in 24 hours.

[Biglou13]

@day-   i get it, high tech, fast with appropriate results (which i give sometimes weeks depending on thickness)    I like!   modern approach!     When you get a chance  please post some images of process. this weekend warrior is interested.

 

i found some info on the 'net  recently.... explaining warping  if piece is dried on flat surface,   top surface dries faster than bottom,  clay contracts as it dries causing warping,

 

 

me-   when dried between dry wall sheets  both surfaces dry more evenly,  cautious of edges drying faster i put in loose dry cleaner bag others wax edges--- slows drying and more even drying---i weight the sandwich for good measure. 

 

hypothesis--  with items that cannot be sandwiched, dry on ware board covered  and dry painfully slowly....

[oldlady]

this weekend warrior is interested.me too!

 

i found some info on the 'net  recently.... explaining warping  if piece is dried on flat surface,   top surface dries faster than bottom,  clay contracts as it dries causing warping,

 

 

me-   when dried between dry wall sheets  both surfaces dry more evenly,  cautious of edges drying faster i put in loose dry cleaner bag which is non absorbent and leaves the piece wet longerothers wax edges--- slows drying and more even drying---i weight the sandwich for good measure. how long do you leave it there?  do you move it to a drier piece of drywall as it dries?  if the object is to remove moisture would that not be better?

 

hypothesis--  with items that cannot be sandwiched, dry on ware board covered  and dry painfully slowly..  

[Biglou13]

 

this weekend warrior is interested.me too!

 

i found some info on the 'net  recently.... explaining warping  if piece is dried on flat surface,   top surface dries faster than bottom,  clay contracts as it dries causing warping,

 

 

me-   when dried between dry wall sheets  both surfaces dry more evenly,  cautious of edges drying faster i put in loose dry cleaner bag which is non absorbent and leaves the piece wet longerothers wax edges--- slows drying and more even drying---i weight the sandwich for good measure. how long do you leave it there?  do you move it to a drier piece of drywall as it dries?  if the object is to remove moisture would that not be better?

 

hypothesis--  with items that cannot be sandwiched, dry on ware board covered  and dry painfully slowly..  

 

not so much wet longer but  the key here is dry slower, and hopefully more even drying. bag is loose  with holes so there is some evaporation going on.  i leave it until its no longer cool to the touch, then dry on wire shelf.  its been humid so i have a thick piece going on 1.5 weeks.  smaller tile went one week. i check the piece occasionally flip, and flip dry wall the the non contact side is drier. if i had more pieces i would switch them out. I'm in no hurry. (i scrounged my dry wall for free,  from friends working on house).  i checked piece today  much drier than last time  edges drier than center,  but center still cool to touch.   sometimes ill put piece out for a few hours open,  flip and let sit for same time.   then back in sandwich and bag.....

[weeble]

I often dry tiles in layered stacks of drywall, but then I'm not usually doing highly textured tiles, just rolled in plant stuffs.  I wrap the stack in plastic so the edge tiles don't dry too fast, then swap the damp drywall out with DRY drywall every day or so and let the wet stuff dry for tomorrow.  That way I can get away with firing the kiln in the same small room as I dry stuff.

 

One of these days the kiln MAY get a dedicated room, meanwhile everything is in one small room.

[stephsteph]

pounding vs rolling. i think it depends on the clay and also the size of the slab. in most studio cases it will not make a difference, but when you begin to test the limits of the clay body you are using , with very large tiles for example, you may see a difference.

 

just as with throwing, cracking and warping occurs when there id a variation from  compression to tension..cracking occurs when there is an area that is stretched more (increases tension), warping occurs when there is an area of greater compression.

 

so the main thing is, whatever you do ,do it consistently. On large tiles where slabs are pounded (compressed) into a mold after being rolled out  or thrown(Stretched, tensioned), problems can occur where you pound  or compress one part of the tile more than another.

i worked in a RAM press tile shop for awhile and there was never a problem with warping or cracking even on very large pieces.

 

if you have a claybody that is problematic this is just one of many, many  factors that may affect   the outcome.

 

BTW..compressing clay rather than rolling it was the standard in architectural clay slab production, but the clay used for very large scale work is very different than the typical bagged  clay we purchase. It is very wet, so as to be maleable enough to slam into large molds and make large slabs,, but also has a higher grog content and is not very plastic.

[LovesPurple]

I have both pounded out slabs for tiles, and rolled.  I did not see a difference.  I built myself a slab roller and it makes the whole process super easy and fast.  I dry my tiles between drywall boards.  I have a huge pile of them, and I put the damp tiles on new boards every day.  I also put weight on top of the pile of tiles between the drywall.  I found I end up with flatter tiles that way.

[Bob Coyle]

Speaking of tiles...

 

I made a set of 8 x 8 x 1/2 inch tiles for a table top. I followed all the instructions... flipped 90 deg and over after each roll...let the clay fall off the board rather than pulling it off... dried the clay for weeks between drywall... bisked and fired the tiles on clay wafers I made so that they would not be in contact with the shelves.

 

They still warped like hell! Asked around and everyone says I did everything correct. Any idea what went wrong?