Multi part molds

Here is something I have been working on for a few months. These projects take a while to develop and my efforts are always worth it no matter where I end up. I gain new information that guides me along the journey. 

It all started when I saw an article in Pottery Illustrated that showed a potter who was slip casting by making lots of molds into one mold. I won't go into to many details as the process will make your head spin, at least it does mine. Basically I simplified this process by breaking down my mold into 4 parts, three parts mold one part hand built......oh yeah, and the handle which makes 5 pieces. 

The basic idea is you can paint colored slip onto the plaster surface than assemble the mold, pour in white stoneware slip, and viola! Out comes a piece with the colored slip inlaid into the the clay body. 

In my design I was inspired by seeds or nuts.

Here is the plaster mold with colored slips painted on.

Mold is assembled.

After the slip has formed the shell I remove the cup from the mold and start with hand building.

I wanted a hand built lip for the cup so they would not all be the same size. Some could have texture, some could be plain, some could be taller than others. The cup is a very personal thing.

After the cup has been built and bisqued I rub iron oxide into the crevices and use my matte bone glaze and fire to ∆6, that's about 2232-2269 f.

Here is the finished cup. I thought it would look nice on my kitchen table amongst the current mess that lies there this morning ( we do try to keep a clean house but with two young boys....)

So I'm extremely pleased with the results! Fun cup to use as well. I only have three made so far but I am ramping up production and they will be available locally soon!

Here is the next stage. A pitcher built in the same process. I learned a few things making the coffee cup and have applied them to the pitcher. The lip and pour spout is very time consuming to make but worth the efforts as It really sets the piece off. I should have a finished pitcher in a couple of weeks.

Still a little clean up to go but it's almost ready for the kiln.

I also got out my first cheese mold. Next week it comes out of the kiln and gets a clear glaze. It's coming along nicely.

Mold making for cheeses

Yesterday I made a cheese mold, yes, a mold for a mold that makes milk mold. A cheese mold. I thought I might share with you how I made it. The type of cheese mold I was making is a basket mold that can be set on a press for making Tomme style cheeses. You will see from the pictures that it has a slight taper. The dots that you see will be guides for me to put the holes in the finished cheese mold once the plaster mold is removed from the cast piece. 

First things first. I threw an original. It is solid and upside down (When the plaster is cast the clay that is touching the throwing bat on the wheel will be the opening). Allowing for final shrinkage the piece measures 8 1/2" at the top of the mold and 8" at the base with a height of about 4". It's finished dimensions should be about 7 1/2" wide at the top and 7" at the base with a height of 3 1/2". I'm working with about 12.5% shrinkage. Divide any wet dimension by 87.5 to get your final dimensions.

Next I needed to divide the piece in two for a two part mold. Now the cast pieces coming out of the mold will not be in two parts. I am only doing this to make it easier to get the finished pieces out of the mold earlier in the process before they start to warp. 

I used an old plastic lid from a defunct container as a divider. This will keep the plaster from running into the second part.

Next I built up a ring of clay around the 1st part and inserted the second part of my mold walls. I use metal roof flashing. It is cheap and flexible. It comes off my molds very easily and clay sticks to it, making for secure mold walls! A blow out when working with 6 or more pounds of plaster is a nightmare to clean up!

Here you can see the mold ready to be poured with plaster. I use a very simple plaster mixing ratio 3:1 that is 3 pounds of plaster to 1 quart of water. This can be broken down to smaller increments like 1.5 pounds and 1 pint or larger quantities like 9 pounds and 3 quarts, super simple.

For this mold I started out by mixing 6 pounds of plaster and once I poured it realized I needed a little more so I mixed up an additional 1.5 pounds and poured it in as well. 

I use hot water when I mix up plaster and an immersion blender or a stick blender. This gives me about 5-8 minutes of working time, which is more than enough time to mix more and add it in before it sets. I can usually remove a piece from the mold after about 15-20 minutes.

Here is the second half being set up for pouring. I put in a key hole on the top and bottom of both sides of the first piece. I usually use a coin for this. Depending on the size of the mold it can be a penny, a dime, a quarter, whatever works! Also, before I pour the second piece of the mold I use mold soap. This is a product I buy. I have tried many other types of soap and find that mold soap is worth the small amount of money and time it takes to track it down.

Finished mold ready for clean up.

Here you can see the key's that I put into the mold. This allows for a nice seating of the two pieces.

On the mold itself I use a metal rib to clean up the joint. This will make it easier to clean each piece coming out of the mold. Remember, the better you make the mold the better the pieces come out and the less time you have to spend working each new piece.

Here is the final mold. I use a sure form tool to clean all the edges of the mold before it starts to get hard, usually within the hour. Once it set's to its final hardness it is tougher to clean up. As you can see from the mold I try to make the mold with about 1 1/2" of plaster around the mold to get even walls when casting. One other thing to note is that I do not force dry the plaster! It will calcine the plaster and make it a worthless mold. Let it air dry in a warm room for about a week (at least here in the Northwest). At that point you can use it. I will cast these next week with porcelain and show you a finished product. 

Now that the goats are freshening I will be making some awesome Tomme style cheese this spring!

Spring, springity spring

5 year olds birthdays, new baby goats, working in the studio, I've barely been able to read my book these late evenings let alone try to update this blog. This morning has been a time to reflect on all of this as the sun gently makes its way over the horizon of the lake. The Alder trees still do not have any leaves on them, a stark reminder of winter. But the ground is green and the grass looks like it wants to be mowed. The plum tree out of the kitchen window is in full bloom and the moon was aglow last night. Today truly is the first day of spring!
I have some pictures to share as I have tried my best to document the activities of the clay studio this past week! First of all I have been re-working the plate hump molds. They worked well enough but I have had this nagging feeling that I was not truly happy with them. Sometimes it takes a while before I can truly say if I like something or not.
The plate molds are made of plaster and a fix to the wheel with a triangle bat system. Originally they came with plate molds as well but I grew tired of the standard shape so I threw a clay mold and poured my own.
I was using a floral pattern on the rims that I picked up from a wooden table top but felt it was to ornate so I sanded it off and carved my own motif (see last post for pics of the old design). Yes, I wore a dust mask.

small plate mold with carved design

Bowl mold

Finished large 9" plate

After the old design was scraped off I carved in a new one. It's more of a doodle and reminds me of papyrus or dragonfly wings. I love the organic shape! I will post more information on throwing plates upside down. I shot a video but I need to do it again....meh. 

The studio was also busy with residents and guests. Here is a bisque unloading followed by an impromptu evaluation. Some of these hand built plates will be going into the wood fire kiln which I believe will be happening soon. I'll get some shots of the anagama in action and share them with you.

Joyce and Mari

Lots of textural choices

I feel like I only grabbed a snippet of what was really going on this week. Spring really is here. I will leave you with this video of the new doelings. They are both dolls. Hope you all get to play in the clay this week!