With the plaster backing done for the rubber positive I made yesterday, I removed the assembly from the rubber mold. Once the plaster backing on this master positive is soaped up well, I can make the plaster piece-mold of this for pressing the terracotta into, The piece mold will be made in at least 5 pieces, most likely about 8 pieces.
It won’t happen very soon as I used up the very last bag of pottery plaster I had on hand and I’ll have to order more along with some other materials and I need some more clay, but I don’t want to order clay when it’s below freezing, so I may order the clay in the spring and order the plaster and other stuff I need now- soon!
I’ve begun the process last night to take my design towards making it in hand-pressed kiln fired terracotta, that requires two additional mold making steps, the first of which is making a rubber positive master cast using the new rubber mold, the second step is making a plaster piece-mold taken off the rubber positive.
Shown below is the rubber positive that was poured in last night- the remaining cavity not filled with that amber colored rubber will be filled with plaster to save on expensive rubber since only the face is the important portion of the design.
The amount of rubber shown in the mold was 2 gallons total, and this cost just about $200, so it’s easy to see how much it would cost to fill this the rest of the way up with this rubber!
Once this rubber is cured and the cavity filled to the top with plaster, it’s taken apart and the plaster and rubber master positive can be used to make the plaster piece mold.
This is similar to the way this was done for the originals my work is based on, though the final plaster piece molds are made identically to the way they were for these pieces back in the 19th and early 20th century when these ornaments were used on building facades.
All of the Sullivan/Elmslie designed terracotta ornaments were made exactly the way I make them- hand-pressed clay into plaster piece-molds, and then final finishing and detailing all done by hand one at a time.
The Virginia Museum of fine art which has a few artifacts from this building also has at least one of these lunettes with a very similar design on it as the spandrel panels have.
I like the shape of it as well, I have no plans to but easily could make the surrounding flat pieces for it if a client wanted them.
I will be working on this model very soon, of course it takes time and this type of work is done when I have time, and more time for the various mold making processes to get done, but progress photos will come along here soon enough.
This would most likely be priced around $325 in fired red terracotta.
The museum has their artifact sized 18-1/4″ x 18-1/2″ and 4″ deep, this size would fit into my existing kiln, so this is another design I can keep my model of full sized like the originals and offer both interior cast-stone this size but less deep to hang ON the wall, and hand-pressed terracotta which will be slightly smaller due to the shrinkage of the clay but made a nominal 3″ deep which can be additionally used outdoors in the garden or embedded into a brick or stone wall of any type.
Dankmar Adler, 1844-1900
Louis Sullivan, American, 1856 – 1924 (Architects) Northwestern Terra Cotta Co., probably modeled by, Kristian Schneider 1884-1885
I just ordered the two gallons of pourable mold rubber I need to “convert” my “Sullivanesque” design that was recently finished- into a form I can take a plaster piece mold from for pressing terracotta into. Two gallons is not enough to fill the mold, it is only enough to pour about 1″ deep, the rest of the depth will have to be plaster to save on the costs of not having to buy two more gallons of expensive rubber.
I’m finished with this Sullivanesque model now and plan to start making the mold to-morrow morning. it’s moist clay, somewhat firmer than it was as it started losing moisture, but it’s still delicate and a paint brush can leave marks on the surface so I have to almost flow the first coat of rubber on rather than firmly brushing it on.
I wanted to get the mold made before it dries since as it dries and becomes completely dry the clay shrinks about 15%, and then when pressed clay copies are made those would also shrink almost that much, so the double shrinkage of about 25% would seriously reduce the final size which I want to avoid by doing hte mold while it’s still moist and nearly the same size it was when I set it up.