I start by mixing the clay with an electric drill mixer. Although we originally get the clay in gallons, it needs to be mixed before every use to make it uniform, otherwise pieces would come out lopsided and weak in places. So after the mixing, here is what a bucket of liquid clay looks like:
Next step, pouring the clay (called "slip" in ceramic terms) into our mold which is made out of heavy plaster. The plaster will absorb the water from the clay, pulling the clay into the sides of the mold, which creates the "skin" or shape of the piece we are molding. This next picture shows the tree mold being slowly poured with our clay slip.
Once the water starts getting absorbed by the plaster, you will see the slip start to recede within the cavity of the mold. So we slowly add more slip to fill it up. The pouring for this piece will take approximately 15 minutes. But each piece is different and must be checked to be sure that enough of the clay has formed a skin within the mold, otherwise the piece will be too thin and fragile.
Once the desired thickness is achieved, I slowly pour out the remainder of the slip back into my original bucket to be used again. Pouring out the mold takes a few minutes and requires a good bit of turning, twisting and maneuvering to remove any pockets of the clay from inside the piece. The mold must be left upside down for a few minutes to allow the remaining slip to pour out. This is also the start the drying process inside the mold, which we want to be as even as possible.
Want to build muscle? Start making ceramics! I have to tell you, with the tree mold having a dry weight of 20 pounds, then adding wet clay, the mold ends up weighing over 32 lbs. Lifting, pouring, pouring out, etc. - that will build muscle on ya! ;)
Since the mold has absorbed the water from our slip, the mold itself will stay wet for about a day or two, making it difficult to pour another piece because the mold will not absorb as well the 2nd time. So quite often, we can only pour one piece per day. At times we can get two pieces in a day, especially if we can place the mold outside during one of our sunny Arizona days which helps it to dry.
Now that our piece is poured out, what next? Well, if you have not noticed yet... ceramics is a messy business! Liquid clay is not a neat and tidy substance to work with. In fact, it gets everywhere. Once it dries, it will be brittle and can turn into dust, so getting it off of our mold needs to take priority not only for the sake of mess, but also to keep the mold in good condition.
Now the mold is cleaned, and the neck of the mold has been trimmed as well. The piece needs to sit in the mold for a few minutes more to be sure that it is set and slightly hardened, otherwise it will turn to mush when we try to remove it.
Now we are ready to take the tree out of the mold. At this stage, the tree is made out of very wet, malleable clay. We must remove it from the mold before it gets too dry or else it will crack as the water absorbs further into the mold and the drying clay starts to shrink. Most pieces are a little stubborn.... enter the mallet!
This Christmas Tree mold is made of 3 separate sections. Each section must be removed separately and very carefully so that we do not smush and ruin the details on the tree itself. When the last section is ready to be pried away from the piece, I use a large rubber mallet to gently strike the mold which creates just enough jarring motion to help the wet clay tree to separate from the mold. The piece sort of "pops-up" slightly as I pound. This is always a tricky bit because I certainly don't want to chip or break the delicate clay piece; which can and does happen - but I also want to get our tree out of the mold, so I have to risk it! ;)
Once the tree is out, you may notice that there are no holes in it yet - so how are we going to light our tree? I use a small drill bit to hand-drill each of the 50+ holes in our tree where all the colored lights will go, plus I have very carefully position the bit and drill the top of the tree for the star. Although the clay is still wet, special care must be taken not to crack any of the limbs, or to apply too much pressure which could cause the tree to collapse altogether.
Whew! Our tree is ready to be dried now before it moves on to the next step.
Time for the start of pouring the clay into our tree mold until the holes are hand-drilled is 1 and a 1/2 hours. Tomorrow, the tree will be fully dried and we can start to clean the mold seams and our holes to get ready for firing in the kiln. The base for this tree was poured at the same time and you may notice it in the background of a couple of the pictures above.
I hope you enjoyed this little glimpse into the start of making our Christmas Tree out of clay. Join me in the next post to continue making our tree, and meanwhile, please leave me a comment and let me know what you think! :)