I am thinking about what to pack...I will be renting a room in someones house and we will be sharing the kitchen, bathroom and living spaces so really I only need to bring clothes, toiletries and some things I can't live without, like my espresso maker. The real challenge is to try to anticipate what I will need for a three month span...that is a long time and a lot of potential weather changes. In terms of my studio I plan to take essentially everything except my wheel, my kiln and the building! I figure my poor little truck can hold about 1000 lbs worth of materials...I have 500 lbs of clay and plaster alone and (anticipate needing to order more)...everything else will be molds, tools, clothes, my bike, etc.
So this week (and really for the good part of the summer so far) I have been making molds. As I mentioned in my first blog the project will be broken up into 4 seasons, each season comprised of a different set of forms. Winter will be masses of snowball like shapes some of which have a texture and some will be smooth (although they will all have an uneven snowball like surface...not perfectly spherical). The snowballs are forms that I have made myself from beginning to end. Spring will be masses of birds, the birds come from commercially produced molds, so all I had to do was buy them and I will "pour" the clay into the molds to make multiples. Fall will be made up of twigs, here I have taken twigs chosen from when we cut back our corkscrew willow tree. It ended up being the perfect tree because it has a relatively smooth bark with just enough texture to look branch like but not so much that there would be challenges with undercuts when making the plaster mold (I will describe an undercut when I get to the images). In the case of the twigs I have taken an existing object and made a mold of it in order to get a ceramic replica of the object. Finally, summer will be made up of grasshoppers, here in Arkansas when things get really hot (right now if is 99 degrees F. and it is only June) we get a ton of grasshoppers and they eat all of my plants right down to the stems. I associate them with the sweltering, withering heat of the summer and the death of my garden not only because they aid in its demise but also because they are really bad in late July and August when if they haven't killed the plants the heat almost surely has. This is a time when going outside feels like the sun and heat are searing your skin and the leaves and grass smell as though they could combust into flames at any moment. For summer the grasshoppers will be my forms...this will be my greatest challenge as I have to make the molds for the grasshoppers by hand (using plasticene, a non drying oil based sculpting material) in a way that will both look like a grasshopper and not have any undercuts which would make removing them from the mold impossible. I will also need to make seperate molds for the grasshoppers legs and to make a few grasshoppers so I have multiple sizes...so keep your fingers crossed for me.
Here is a brief-ish photographic overview of the mold making process:
This is a clay ball that has been covered in plasticene and then pressed with a hand carved clay stamp to make texture. The clay ball is used as a form because making it of solid plasticene (especially as I have made about 15 -20 in varying sizes) would be expensive. I will make the grasshoppers in the same way, plasticene over another form probably also made of clay. The plasticene allows for a crisper texture and since it never dries is re-usable. Once this is made (called a positive), I will build up a clay bed approx. 1-2 inches beyond the sides of the ball and to the exact middle of the height of the ball. This is where it seems easy but is actually kind of tricky. Just keep in your mind that it has to be to the exact middle and I will explain later.
Once the clay bed is made it is closed in by cottle boards. The boards are clamped tightly together to form walls around the form which allows plaster to be poured in. What you are actually seeing below is the first plaster side already poured (the white stuff surrounding the ball is plaster). Note the clay that runs up the corners of the cottle boards, this keeps the liquid plaster from oozing (sometimes pouring) out the sides...also known as a plaster disaster because once the dam breaks it is hard to keep the plaster in. Once the cottle boards are set in place you can pour your plaster (which is mixed up in a specific ratio of water to plaster that allows for maximum durability and water absorption). You pour the plaster into the mold until it is approx 1-2 inches above your positive. Again because you want even water absorption the walls need to be the same thickness all around the mold if possible. After the plaster has set up, which takes about 30 mintues you unlock your cottle boards, flip your mold, remove the clay bed and then lock it up in the cottle boards again. As I mentioned above what you see here is the mold after the first plaster has been poured, it is back in its cottle boards, all the seams are sealed up and I have made my plaster keys (the depressions in the plaster that aids in lining up the mold parts when completed).
Here I have made a dam half way through the half sphere. A more talented and patient mold maker could make a ball mold in two parts but to be on the safe side and because my spheres are not perfectly round I have chosen to make them all in three parts which allows for some leaway in terms of undercuts, although it means I will have more seam lines to clean up on the caste spheres. You can see that I have poured the second of three parts, the wavy lighter grey line in the middle of the form is the clay dam that will be removed before I cast the third part.
Below you can see the mold two thirds complete and out of its cottle boards. Each time you pour a plaster part you need to coat the plaster mold in mold soap or mold release. This creates a film between the two plaster parts which would otherwise completely stick together rendering the molds useless.
I probably shouldn't show so much detail because I will hear from my professional mold making friends but as I tell my students it takes time and practice to get better. Here you can see the bubbles from the mold soap, which needs to be cleaned off before I pour the plaster or the bubbles will show up in the mold. You can see also how tight the seams against the form and between the mold parts is...this is because when the mold is complete liquid clay (slip) will be poured in and if the seams arent tight the slip will come right out of the open seam. 
Below you can see two three part ball molds. Jeannie and Derek don't laugh...I will clean them up so they look better and in some cases are lighter to lift. I have chosen to make all of the ball molds as seperate three part molds instead of including multiple balls in a single mold which would allow me to make two to three balls in a single pour. I am doing this to keep the weight of the molds down, since they get heavy when filled with slip and they have to be lifted and turned over to drain the slip back out.
In this shot I have poured the liquid slip into the pour gate, I have simply drilled a hole that is the same size as the funnel I am using to create the pour gate. The molds are held together by the rubber bands you see around them, this is adequate for the smaller molds but the larger ones will requires tie down straps (like what you use to hold stuff down in your truck). If the plaster molds are completely dry it takes about 10 minutes for the slip to be ready to drain back out. The way it works is briefly as follows... The dry clay is mixed with a combination of water and sodium silicate, the sodium silicate allows the slip to flow without the addition of too much water, the alkalinity of the clay is such that when sodium silicate or another deflocculant is added the clay particles become ionized,the electrical charge produced causes the clay particles to repel each other and therefore flow with less water (the clay particles don't settle in the bottom of the bucket but rather stay in suspension in the water). This also allows you to pour multiple castes in one mold becasue there is less water to be absorbed. SO...once you pour the slip in and some time elapses the water is drawn out of the clay and into the plaster mold, this results in a drier thin skin of clay which coats the interior of the mold, the longer you wait the thicker the skin gets. Once the skin is the thickness you desire you pour the remaining slip out of the mold again through the pour gate. Then you wait longer 30-60 minutes or more depending on how damp your mold is, and finally you pop your clay piece out of the mold by pulling all of the mold parts away and you have an exact (hopefully) hollow replica of your original positive! Because the slip is liquid and the mold parts have to be pulled away undercuts which I mentioned above are a challenge. Take a simple sphere for example, if I had made a two part mold and the first or half had not been perfectly centered to middle of the height of the ball the plaster mold would have come up far enough to cover the ball as it curves to its widest point and then past that it begins to curve to its smallest again at the top. Imagine having done that in a two part mold...as you pull the two parts away from the ball it would rip it in half on the side where you went past the widest centerpoint...get it? ...Maybe?
Voila! multiple clay spheres ready to be cleaned up and made into a sculpture...I will patch the hole which is a result of the pour gate and when necessary clean up seam lines. The forms will then be massed together like you saw in my maquette images on my first blog and fired, glazed, decaled and generally made more beautiful...
These are a little more interesting...I think...two twigs on the outside with their ceramic twins on the inside, note there is some shrinkage and will be even more post firing due to water leaving the clay etc.
Closer shots of two twigs and a ball
Can you see some of the nice detail...the bumpy texture of the bark and a few places where new leaf brachnces were starting to grow!
So there you have it...a pretty detailed version of my mold making...It takes a long time to make the molds but once they are done you can make the clay casts pretty quickly, you can pour all of the molds at once and in an hour have 10-20 pieces made and then do it all over again.
It looks like I am going to have to spend some time when I first arrive in Minneapolis making more molds which is what I wanted to have done by this time but it didn't happen (I'd like to think partially because it took about three weeks to get plaster as the only distributor in Arkansas which is right by my house in Little Rock had it back ordered.
Well it is late but I wanted to get this complete since I am hoping to write each Sunday (I know it isn't Sunday but we were in Washington D.C. this weekend so writing this blog was out of my reach). I'll try to write again this Sunday...the night before we leave for Minnesota!
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