In my last post I mentioned that I was going to pour some plaster molds to make square rice bowls. I found a really cool square bowl in the after-Christmas sales and thought, “Hmm. That would make a great rice bowl,” so I picked one up and brought it home. I spent a couple of days making the molds and documenting the process in pictures, and here it is!

	First, I gathered the supplies. This is very important because once the plaster is mixed, there is no going back! It will set up while I’m searching for things. Here you see the bottom and side boards (called casting boards) for the mold, clamps, the square bowl, clay, buckets, mold soap (really Murphy’s Oil Soap), and a paintbrush.
	I clamped the casting boards together using the square bowl as a guide. I left about 1.25 inches of space around the bowl.
	The next step was to seal the corners of the mold. I pressed coils of clay into the side and bottom corners. Without this seal, plaster leaks out of the mold and makes a huge mess. I’m wearing latex gloves here because experience has taught me that plaster destroys my hands. It sucks all the moisture out and leaves them dry and cracked.
	After all of the corners were sealed, I applied mold soap to the casting boards. This makes for an easy release of the boards when the plaster has set up. No need to soap the bottom board since it’s formica and the non-porous surface will release from the plaster easily.
	See the writing on the plaster bag? It says breathing plaster is BAD FOR YOU. That stuff settles into your lungs and doesn’t come out. Same with powdered clay particles. That’s why it is important to have the right type of particle filtration mask. I wear it anytime I’m messing with the plaster bag or pouring dry plaster into the bucket for mixing.
	The dry plaster was added to water, then mixed by hand until it reached the consistency of thick cream. I mixed slowly to try to avoid bubbles. The bubbles that you can see on the top of the bucket were scraped off and dumped in the trash.*
	Next, the plaster was carefully poured into the mold. I use a smaller container to scoop and pour the plaster, and pour it over my hand to try to reduce bubbles. Once I had filled the mold, I set the bowl into it at an angle and bounced it up and down gently. Again, this was to try to get any big air bubbles to rise to the top.
	I weighed the bowl down until the top was at the level of the plaster. I let it sit for 40 minutes or so, then removed the bowl and the boards. Plaster gets hot while curing, so I wait until I feel it starting to cool down before I remove the casting boards.
	The mold after the boards and bowl have been removed. It’s ready to be cleaned up and set on a rack to dry.
	I use a fettling knife to knock off all of the sharp edges. A word of warning - don’t leave damp plaster on your tools! It will set up hard as a rock and is hard to clean off. Speaking from experience here. The final cleanup was a wipe-down with a damp sponge.

One step I didn’t photograph was the cleanup. I have a small bucket with a plastic bag liner and as soon as I poured the plaster, I scraped the rest of it into that trash bucket. Then I gave my mixing bucket a quick wipe with a sopping wet sponge and poured that water into the trash bucket too. If you let the mixing bucket sit, the plaster will set up and be impossible to remove. The key is to have everything set up and to work fast.

*NEVER pour plaster or plaster water down the sink drain!! You’ll be sorry. And you’ll have an expensive plumber bill.

Altogether I made three molds and am happy with two of them. They’ll need to dry for a couple of days, then I’ll make some bowls and post the results right here. Stay tuned!

In my last post, I mentioned using cardboard tubes as curved molds for slabs of clay. Here’s an example of a vase I made using this technique. I rolled out slabs of clay, then laid them into the half-tubes. Once the clay was stiff enough, I took it out of the tubes to work with it. I found the cardboard tubes to be problematic, though, because the moisture from the clay caused them to lose some curve. So today I decided to make some plaster hump molds. Hump molds are designed to lay slabs of clay over, as opposed to slump molds which allow you to slump a slab of clay inside.

First, I laid slabs of clay into the tubes. Then I put more slabs at the ends and sealed up the cracks with coils of clay, then smoothed it all out to make a nice surface for the plaster. I let those sit until the clay was a little past leather hard, not dry yet, but not quite pliable.

Then I assembled all of the materials I needed. Everything must be within reach when working with plaster. It starts to set quickly so I didn’t want to mix it until I was ready. I measured the water and weighed the plaster - two gallons of water, 22 pounds, 13 ounces of plaster. Then I mixed the plaster and poured it into the molds. Here is a picture of the large mold, then the measured water and plaster, and the molds once the plaster was poured:

Here they are after setting up and being removed from the molds. At this point they are still pretty wet, and have some clay residue left on them. I’ll sponge them off and allow them to dry for a couple of days before I use them.
The finished products were one large and two small half-round molds and a tile mold. One great advantage of using a plaster hump mold is that a slab of clay will dry much faster than another material. The plaster actually pulls water out of the clay. These molds will cut the waiting time down when making handbuilt items.

A couple of weeks ago, I sold a mug to a co-worker. When I delivered it, he excitedly picked the mug up and grabbed the handle. He looked at me and smiled, “Wow! I can fit three fingers through the handle, that’s good!” It was then that I realized this guy has huge hands. He stands about 6′2″ tall, and is just generally a big-boned guy. I bet he seldom, if ever, comes across a cup or mug with a handle that he can get all of his fingers through.

I remember that when I gave my Dad a mug for his birthday in March, he comfortably fit two fingers through the handle. I could stick all four fingers through that same handle. I don’t know why the light didn’t come on that day, but it didn’t. After the occurrence with my co-worker, I started paying closer attention to the hands of the people I came in contact with, in all of my different walks of life (only a potter would understand!) and realized there are a lot of men out there with large hands who might appreciate a mug with a handle made to their size.

So this week, I set out to make some man-sized mugs. I threw larger mugs than I normally do, and affixed wide strap handles to them. Now, I can fit my entire hand through these handles in the leather-hard stage. I am anxious to see how much shrink I get out of them. When they’re finished, I am going to take one in to my co-worker to see how it fits his hand.

Here is a new form I’m playing with. This one is going to be pretty small, next time I’ll try a taller pot, or maybe a bigger round one. I threw a small cylinder and rounded out the bottom. Then, I closed the form at the top. I dried the form on a hardi-board shelf, then when it was leather hard, I trimmed the bottom into a nice round shape. After it was trimmed, I brought it to the table and drew out the pattern, then carved it out very carefully with an exacto knife. The final step was to clean up the edges of the cutouts with knife and sponge.

I think this little pot might have all sorts of fun uses. It could be used as a vase for short-stemmed flowers. Or a toothbrush holder (in a taller model). How about a pencil holder? Or, just a neat decorative piece for a table or desk.

I have some ideas for some new forms, so I am going to write them down here so I don’t forget.

Pillow vases - small pillow or box-shaped forms with holes in top for single flowers or small bunches of flowers with small stems.

Hobo bag vases - small bag-shaped vases with a ribbon around the top. I’m picturing a bag shape like a bandanna, if it was full of stuff and tied to hold the stuff in, with the cloth sort of ruffling around the top.

Incense burners - long, narrow holders, curved at one end with a hole to hold an incense stick. Maybe on little feet?