Plaster and ceramics go hand in hand. We ceramic artists use plaster for everything from drying or wedging surfaces to stamps or molds for slip casting. But potter Lauren Sandler has been making hump molds for her work out of unfired clay. This way she doesn't have to deal with the mess of plaster, doesn't have to wait for her molds to dry and be fired, plus, if she gets tired of the form, she can reclaim the clay for some other use. Now, I don't mean to diss our good friend plaster, but I do love the simplicity, speed, and versatility of this method. Check it out and see if you agree!
In inspiring prepared to water cut, arranging is pivotal. Keep in mind that since you're utilizing ModPodge® as a safe material, the regions secured with it won't be water carved and will stay raised. Arranging your drawings and examples includes pondering both the positive and negative space.
You can draw specifically on the dirt with the ModPodge® or you can utilize paper stencils to cover off ranges. Utilizing paper cut outs gives you super clean lines and additionally permitting you to lay out your outline before hand, ensuring all the pictures or examples fit and work pleasantly together. Strong lines and shapes work best, while slight or fragile lines and shapes tend to wash away too rapidly.
Making the Mold
Begin by making a clay mold that will be used to drape a slab over. The mold will be used to make the bottom quarter of the final bowl form that will then be built up to the finished shape and height with coils. The mold is made upside down and solid-later it will be turned upright and hollowed out. I start by drawing a boundary line to follow by first cutting out a paper pattern for what will be the top of the mold (when upright) and outlining that on the bat (figure 1).
I begin the mold with a large thick slab, cut around the drawn line then add and remove clay as needed to create the desired form (figure 2). Take your time in shaping the mold; even out and smooth the surface with a Surform tool or rasp, then refine the shape and the surface with metal and rubber ribs. Place a bat and a torpedo level on top of the form and make any adjustments needed until it is level (figure 3). Once the mold has set up to a firm leather hard (wet enough to hollow out, but firm enough to hold its shape when handled) turn it upright and examine it. Check the shape to assure that the shape is what you're looking for and add or remove clay as needed.
At this point you can hollow out the form leaving ½-inch thick walls (figure 4). Once finished, let the mold dry for a few days. The mold doesn't have to be bone dry before using-just dry enough so the slab won't stick to it. For a longer lasting mold, you may want to make a plaster one; although I have been using some of the same bone-dry clay molds for a couple of years - and that includes many moves. The edges will often chip, but I usually cut the bottom part of the slab off above the chipped parts so it doesn't interfere with the form.
Source : http://ceramicartsdaily.org/pottery-making-techniques/making-ceramic-molds/forget-the-plaster-how-to-make-a-surprisingly-durable-hump-mold-out-of-unfired-clay/
In inspiring prepared to water cut, arranging is pivotal. Keep in mind that since you're utilizing ModPodge® as a safe material, the regions secured with it won't be water carved and will stay raised. Arranging your drawings and examples includes pondering both the positive and negative space.
You can draw specifically on the dirt with the ModPodge® or you can utilize paper stencils to cover off ranges. Utilizing paper cut outs gives you super clean lines and additionally permitting you to lay out your outline before hand, ensuring all the pictures or examples fit and work pleasantly together. Strong lines and shapes work best, while slight or fragile lines and shapes tend to wash away too rapidly.
Making the Mold
Begin by making a clay mold that will be used to drape a slab over. The mold will be used to make the bottom quarter of the final bowl form that will then be built up to the finished shape and height with coils. The mold is made upside down and solid-later it will be turned upright and hollowed out. I start by drawing a boundary line to follow by first cutting out a paper pattern for what will be the top of the mold (when upright) and outlining that on the bat (figure 1).
I begin the mold with a large thick slab, cut around the drawn line then add and remove clay as needed to create the desired form (figure 2). Take your time in shaping the mold; even out and smooth the surface with a Surform tool or rasp, then refine the shape and the surface with metal and rubber ribs. Place a bat and a torpedo level on top of the form and make any adjustments needed until it is level (figure 3). Once the mold has set up to a firm leather hard (wet enough to hollow out, but firm enough to hold its shape when handled) turn it upright and examine it. Check the shape to assure that the shape is what you're looking for and add or remove clay as needed.
At this point you can hollow out the form leaving ½-inch thick walls (figure 4). Once finished, let the mold dry for a few days. The mold doesn't have to be bone dry before using-just dry enough so the slab won't stick to it. For a longer lasting mold, you may want to make a plaster one; although I have been using some of the same bone-dry clay molds for a couple of years - and that includes many moves. The edges will often chip, but I usually cut the bottom part of the slab off above the chipped parts so it doesn't interfere with the form.
Source : http://ceramicartsdaily.org/pottery-making-techniques/making-ceramic-molds/forget-the-plaster-how-to-make-a-surprisingly-durable-hump-mold-out-of-unfired-clay/