Thursday, March 20, 2014

February Hints of the Week

FEBRUARY 2nd HINT FOR THE WEEK: Making Molds without Plaster
copyright 2001, Cindi Anderson, www.bigceramicstore.com
What if you don’t want to use plaster, but you still want press molds, or slump and hump molds. Never fear, as there are other options! 

1. Bisque: You can make press molds out of clay and bisque them. These work quite nicely and clay doesn’t stick to them. Carve the inverse of your desired design into leather hard clay. For example, if you want raised lettering, carve the letters out of the press mold and the inverse will be raised. Remember to make your design about 10% larger than desired, to account for shrinkage.
Bisque also makes great slump and hump molds. These can be thrown, or handbuilt, or molded from a found object.
You can use found objects (mixing bowls, platters) directly by coating with vegetable oil, PAM, WD-40, etc. or by covering with plastic wrap or newspaper. Usually you will use these as slump molds, as the insides of your bowls and platters have the nice curvature you are looking for.
 

2. Wood: Wooden bowls can often be used directly without any coating. Wood is porous so clay doesn’t stick. Keep an eye out for wooden bowls at garage sales.
 

3. Canvas: You can also make a sling out of canvas and use that for your mold. For example, take a piece of canvas and put it over the top of a large round garbage can. Where the canvas overhangs the can, wrap tightly with string. Place your slab on the canvas. You can get different curvatures depending on how tightly you pull the canvas. This same technique can be used with buckets for smaller slabs.
Here’s a great variation on the previous idea, that I just thought of! You can cut holes in the canvas where you want the feet to go. That way you can attach the feet while the clay is still wet, and not have to worry about getting it off the sling at exactly the right time, when it is hard enough to hold the shape but still soft enough to add the feet! Cool huh?
A similar approach to the above is to put the canvas over a plywood box. Staple the canvas to the outside of the box. Again, the curvatures can be modified by how tightly you pull the canvas. You can staple just two ends, or all four ends for different effects. If you want to make this more versatile, make a version where you can vary the amount of curvature. Attach screws or nails to the outside of the box.
Or, (here’s my laziness coming through again… I’d rather think of a better idea than go to the trouble of making a plywood box), how about using clothes baskets! They come in round or rectangular, and are inexpensive. 


4. Newspaper Another thing you might consider is making a form out of loosely crumpled and dampened newspapers. This allows a more loose look. Shape the damp, crumpled newspaper into the form you like, and cover it with plastic. The newspaper will dry and this hump mold will likely be useable for a while. If it starts to come apart you can squirt the newspaper with water and re-shape.



FEBRUARY 9th HINT FOR THE WEEK: CLAY = DRY SKIN Information contributed by Susan Hickman
My old hands have enough problems without bleeding cracks around my fingers (ow wee!). I have tried lots of things myself that help but I thought it might be interesting to consult the worldwide information box to see what other potters do. Here is what I found out: Why fingers crack and what needs to be done on YouTube: www.youtube.com/watch?v=xC_iKN7CXBI.
Preventive treatment
· Put hand treatment on before you throw or build with clay.
· Wear gloves when glazing. If not, make sure your hands are freshly washed before you glaze to prevent skin oils from causing resist areas.
· After using clay or glaze, wash hands and under fingernails with soap and water. There are several recommendations of following washing with vinegar and air dry hands. Then use hand treatment.
Hand Treatment recommendations:
· User what you have. It won’t do any good sitting on the shelf.
· Potters seem to love bag balm. I work it into my hands for a minute or two and then scrub my hands with soap and water. Dry skin goes down the sink (gross but true). Gene says this stuff stinks but you need to make sacrifices for your art. I usually put another lotion on my hands after washing them.
· There are lots of homemade recipes on the web for you homemaker types (not me)
· Wool wax cream, olive oil, aloe, arnica, hydrocortisone, antibiotic ointment
· Carry carmex or other lip balm in your pocket and work it under your nails several times a day.
· Witches brew: Combine all your leftovers of creams, lotions, gels, ointments and petroleum jelly in a bowl, heat in microwave, and whip together with a mixer.
· “Crack Cream” found at Shopko. Smells funny but must be good since it has lots of natural products in it including Montana arnica flower extract!
· Once you get a crack, make sure it is sealed with ointment and covered until it gets well.Band-Aids aren’t helpful when making pottery. Drug stores sell Liquid Bandage, which is like super glue. Another option is to wear surgical gloves or cut out a glove finger, slip it over your boo boo and tape it around the base to hold it on



FEBRUARY 19th HINT FOR THE WEEK: Hand Measuring Tool by Marty Jones, Ceramics Montly, Feb. 2014.

Before I discovered that my hand was the best tool I owned. I used rulers, calipers, and whatever tool I had within reach that was the appropriate length for what I needed at the moment. When I was making a series of vessels, I got tired of looking for, picking up, (then setting down in the wrong place), the implement I needed to make sure my 7 proportions were always
the same with each subsequent vessel. I realized that, stuck to the end of my wrist, was a ready-made measuring device. By using knuckle joints, wrinkles, creases or folds, or a combination of these, I could place my hand at the appropriate spot and instantly know if my dimensions were on or off.

For example, if I am making coffee cups and I know that I want the mouth to be 3 inches across, the distance from the top of my ring finger (and no other finger) to the fold of skin at the second knuckle is the same length (1). I just hold this across the mouth of the cup. This is especially helpful when making more complex forms such as a wine glass with mouth. That’s five different measurements needed. This tool is always there. There is nothing to pick up or put down. It didn’t take long for me to realize that once I decided the necessary dimensions for a particular piece, I would forget what those dimensions were by the next time I needed to make more of the same vessel. So I made several photocopies of my hand and made notes as to the necessary dimensions of each different pot (2). I tacked this note by my wheel and I simply look up when I need the dimensions for any given piece.





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FEBRUARY 23rd HINT FOR THE WEEK: Tips On Plates & Platters - Pottery Magic http://www.pottery-magic.com/
Making plates can be tricky, and the larger the plate the more likely you will encounter problems. Here are some remedies:

Make sure the clay is thick enough. Thinner plates are more likely to warp. Thickness should be even. Clay should be very uniform, work the clay well.
When rolling slabs, make sure you roll it out evenly in all directions, otherwise you could compress one side more than another.
* When throwing, use soft clay but not too much water or the rim will get too floppy.
* When you carry your wet clay slabs to a different place to form, make sure you don’t stretch it. Put it on a board, or roll it lightly into a sausage, then unroll directly on the mold that you will use.
Plates must be dried very slowly and evenly. Uneven drying can set up stresses that don't show themselves until the final glaze firing.
* It can help to control drying so the center dries faster than the rim. To do this, cut a round hole in the plastic about 3-4 inches in diameter over the center of the plate.
* Some people use water based wax to coat the rims during drying, to prevent them from drying too quickly.
For large platters, you probably need two foot rings, one around the outside and a smaller one left in the center. Otherwise the center of the plate may sag during firing.
* When you place a platter on it’s rim, place it on soft foam to protect the rim and keep it from getting stressed.
* Trimming large platters can cause slumping of the bottom during the trimming process. You can put layers of foam rubber or carpet pad into the center area before inverting * * * * *Place a board onto foam rubber or rim then invert the whole thing to turn it over. This “holds up” the center area and prevents it from sagging. It is not necessary to fill the whole center of the plate. If you fill the center only (i.e. a 6” circular piece of foam rubber), it will keep it from sagging.
* Another thing to use in a similar way is socks or larger fabric sacks filled with rice. The rice is malleable so you can push it around until you get the right shape.
* Or still another item to use is a sponge.
* Sharp tools make it much easier to trim without causing deformation. (Remember, clay has memory and even if you smooth out any deformations, they will come back during firing.)
Many people find firing goes much better when they notch the plates' foot rings. Warping, cracking, s-cracks, were all eliminated. The notches provided a way for air trapped under the foot to escape. If the gas can’t escape from bottom it may cause the center of the plate or platter to “bow” up. Just make small, U-shaped notches at the bottom of your foot ring.
* Instead of, or in addition to these notches, drill small holes in the foot ring. This also allows the gasses and heat to escape, and also allows for a wire to be used for hanging. This is especially nice for plates that are too large to fit into standard upper kitchen cabinets. Some people use a single hole, others two close together, others 3 spaced evenly around the platter.
For plates and other items with large bases, make a clay “cookie” at the same time as your piece. This is a sheet of clay (the same type of clay), which you sit your piece during drying and firing. The cookie and the plate will shrink at the same rate. This seems to keep the piece from “hanging up” on the kiln shelf during shrinkage, expansion and contraction. For extra assurance, put a wash of alumna hydrate on the feet and the cookie.
Another method is to cover the shelves with grog or sand

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