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Large platter with altered rim and surface texture and multiple colors

Throwing & Trimming Large Platter | Altered Rim and Surface Texture - Step-by-step Tutorial




Throwing a large platter or a bowl using 40-50 lbs of clay can be challenging. Centering and distributing such large amount of clay making it evenly flat for 20+ inches requires strength and years of experience. To simplify the process and enable one with an average pottery skill level to be able and throw large platters or large bowls, we have prepared the improved step-by-step tutorial below, using the principal of breaking the tasks down to more manageable amount of clay in each step. In this demonstration, 42 lbs total about of clay was used to make a 28" diameter platter with slip surface texture and altered rim. The final product is shown on the upper right corner using spread glazes (How to spray glazes).


1) A 30" wooden bat is used with a 1 horse power (or larger) pottery wheel. Plastic bats will be distorted carrying the finished pot around. A plaster Hydro Bat is also a very good choice. This demo starts with a 14 lbs wedged clay to create the 1" flat form thrown shown below on left picture. To properly accept the coil (second stage), it is important that the outer end of the flat form is compressed, cleared from water and slurry and tapered from 1" thickness to about 1/3". This tapered surface is used as a socket to accept the next coil.

1" thick flat clay thrown (14 lbs)
Throwing the platter's bottom
Angled edge to accept coil
Wedge & start coiling 12lbs clay
wedge a large coil
Start rolling the coil
make the coile long to cover the full circle

2) Roll the coil on a non-absorbent table to insure clay stays moist and soft. Make the coil as even as possible. Place coil on the tapered edge created on the first stage flat form.
Continue to extend coil
make the coile long to cover the full circle
Verify needed coil size
Verify coil radius
Carry coil on shoulders
Cary coil on shoulder or get help
Choose texture mats or objects
Place coil over pot's base

3) It is important that the coil is worked in and well blended in the flat form and the coiled ends are well connected. The coil / flat form contact surface is without water and it is not scored. After applying pressure on the coil without the wheel turning turn the wheel on slowly and add water. Apply pressure and squeeze tightly to even out the coil and center it.
Work the coil ends tightly
connect coil's ends perfectly
Wet the coil
Push down while squeezing
even coil to a nice clay wall
Keep thumb low -- better seam
start spreading the wall to increase bottom width

4) Once the coil is centered, is evenly distributes and is well connected to the flat form below, start expanding the attached coil out wards. Every so often use a wooden tool to compress the clay and remove slurry.
Use both hands the expand clay
We love this wooden tool
Use heavy dudy wood rib
Compress and even top surface
compress caly - critical
Expand further using both hands
expand  while managing buttom's thickness

5) It is important that the end of the flat form is compressed, water / slurry free and tapered from 1" thickness to 1/3". This surface is used as a socket to accept the next coil. Being further from the center, the next coil needs be longer and therefore will require more clay. In this demo, the third and last amount of clay is about18 lbs. Because the coil is not 100% even, you might end up with uneven edge. Using extruded coil (as oppose to hand made coil), will eliminate wrestling with unevenness potential. Correct the end by removing the uneven part with a pintool as shown below.
Create a low profile edge
Used wooden rib to slant edge
Center by cutting off the end
cut off the uneven edge
Remove the cut-off end
remove uneven edge
Make the next stage coil
prepare the next coil for pot's wall


6) This next coil is larger that the previous one. Carrying it without stretching or breaking it may require a second person to help carrying it to the wheel or use your arms and shoulders. To attach this second coil properly, follow the same instructions as in previous coil. The clay in this second and last coil will be used the expand the bottom a bit more and for the pots wall.
Verify dimensions
Verify coil's size
Place on tapered edge
place coil on platter's bottom
Place tightly (without water)
Attach coil tightly
Center and even coil
compress and even coil


7) One inch thickness for the bottom is used to be able and trim 1/2 foot when leather hard. Verify with a pin tool for the correct thickness and test in a few spots to ensure consistency.

Use rib to integrate bottom to coil
integrate bottom to wall
Verify thickness with a pintool
verify bottom's thickness with a pin tool
Should be around one inch
bottom's thickness about 1 inch
Expand to desired diameter
pull wall to the desired width


8) Do not turn the wheel too fast to pull the wall up. With larger forms, it is so much more important that the walls are compressed and have even thickness. Before curving the upper wall in for the wide rim effect, make sure the clay is not too wet. You can wait a few hours or use a torch to dry the clay a bit before "bending" the rim in.

Raising the wall
Raise wall
Smooth wall
turn whell slowly and raise wall with rib tools to avoid too much water
Wait or use torch to dry wallyou may use torch or wait until the wall is hard enough to accept the next coil Start curving top wall in
curve wall


9) If the rim is too long (more than 2 inches), it weighs more and can collapse. Cutting the end with a pin tool will reduce the size as needed and will even the rim (using a coil which it is not perfect made by hand, might yield some unevenness). The end of the rim must be rounded to better resist stress cracks during the drying and the firing process.

Use a rib to refine shape
bend wall's edge
Cut end off with pintool if uneven
cut to desired width
Define shapes using 2 ribs
use ribs to create a sharp edge
Round the rim
curve rim with flixible rib
Smooth rim with Chamois
smooth edge with chamois
Rim - profile view
Altering the rim
alter pot's rim
Altered rim top view
completed pot's shape

10) Slip need to be not too thin and not too thick. Thicker than yogurt and thinner than sour cream. We found out that Sherrill Mud tools red rib is excellent for slip distribution and patter creation.

See more about surface texture techniques on the pottery wheel

See how to make large amount of slip

Add slip for surface texture
use compatible slip
Distribute slip
spread slip
Create a seashell pattern
work on slip design
Slip pattern top view
slip ready for drying


11) When finished, cover and let dry very very slowly (1-2 weeks) to avoid uneven drying and therefore possible cracking. If using slip for texture affect, cover rim only for a couple of days as shown below.

Lakeside Pottery's Glaze Recipes

Average size finished platter next to this demo's platter
Cut plastic for round opening
make a hole in a dry cleaning bag
Cover rim for slow drying
place over rim
When slip not wet, cover pot
after slip lost most water, cover the whole pot


Drying and Trimming The Above Large Platter

Drying
1) Cover tight and let the clay moisture content equalize for 2-3 days.
2) If using slip, cover the rim and let slip dry for a day or two before covering the whole pot
3) Cover the whole pot loosely for 1-2 weeks and make sure the rim does not dry first. If the rim drys first on such large platter, cracking at the rim's edge is almost certain. Drying Tip: Flip the plastic cover once a day while drying. The moisture that accumulates on the plastic surface will be facing up after flipping, thus, removing water a bit faster from the enclosed large pot.
4) Before trimming, make sure the pot is on the harder side of "leather hard" to insure the pot does not warps when it is flipped over for trimming.

Where did we purchased the foam? See Norwalk Mattress (ask for Fred). Approximate cost: 22" Diameter - $40, 18"- $24, 16" - $20.

Double sticky tape to hold foam
use large wooden (stiff bat)
22" x 5" foam placed on tape / bat
place foam in center
Use 4 hands to flip platter
use help (4 hands) to flip pot over for trimming.and center
Start trimming with sharp tool
trim outside shape first

Trimming

1) DO NOT place the pot on the altered rim.
2) We use a 5" deep round dense foam that fits on the inside of the pot. Having the ability to access the inside of the pot when it is raised on the foam provide the extra benefit of checking for proper thickness through the trimming process without taking the pot off-center.
3) Place the foam on a wooden bat. Wood is better in terms of binding the foam to the bat so that it will stay in place during the trimming process.
4) Use two people to flip the pot over the foam.
5) Center the pot / foam.
6) Start trimming from the outside of the pot removing excess clay. Trim it using the same techniques as usual.
7 ) Use sharp trimming tools e.g., Kemper's Pro-line Family to minimize pressure downwards trimming close to the center.
8) For such large platter, a ring or two is required to avoid sagging in the firing.

The trimming tools used in this demo are Kemper's PT511 and PT 512 - Web site
Kemper trimming tools

Define pot's wall
Trim to the right width
Define foot
Determine foot width
trim inner part of foot
Dig in full depth
Dig in full depth - inner ring
trim inner foot ring
Remove excess clay
remove all clay between the two rings
Repeat in second section
remove  the center
Round feet edges
burnish surface
Burnish (Sherrill's yellow rib)
burnish surface
Top view
trimming is completed
Side view
side view of trimmed large platter
Trimming chips
Use second bat to flip over (2 people)
place another  wooden bat on top and flip over
Cover and wait 1-2 weeks
cover pot for days to dry slowly to prevent cracking
Close up profile
Making hanging holes
drill holes on pot's foot for wall hanging if desired
Use hole cutter - see link to purchase

Drying Tip: Flip the plastic cover once a day while drying. The moisture that accumulates on the plastic surface will be facing up after flipping, thus, removing water a bit faster from the enclosed large pot


Cover and wait 1-2 weeks
Ready for bisque firingReady for bisque firing Spraying glaze
spray glaze
Finished pot - spray glazed
glazed large platter
Your input is greatly appreciated and will help in creating improved pottery tips.

Thank you, Patty and Morty

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