Today I am working on the plaster piece mold for this panel, the photo shows the previously pictured rubber positive now set up into a wood form for pouring the plaster piece mold. With this first photo two of the five sections required have been poured after putting in temporary clay blocking walls in the other two side sections I don’t want filled with plaster just yet.
These two sections have to set first, and then they get completely soaped in situ and the soap allowed to dry before the next two sections are poured- in this case what is the top and bottom sides.
The last section poured, which is the largest piece and which forms the base/bottom of the mold the four sides fit onto:
The completed plaster piece mold assembled after cleaning up sharp edges is now set aside to dry out before being used. The design can be seen is in reverse (negative), with the inscribed lines on the casts seen here as raised lines. Just like a film negative has the colors reversed and the image reversed, the mold does as well.
When the plaster mold is dry, then the fun begins with the labor of hand-pressing, ramming and compacting the red clay firmly into every milimeter of the inside of the mold, and building it up to about a 5/8″ thickness in the surface and sides. Also for additional strength and stability- additional walls or webs are formed by hand inside to divide up the large opening into about six small compartments just like the original architectural pieces have. The backs of these closely resembles the two compartments that concrete blocks have.
The webbing adds structural strength as well as helps prevent warpage, on buidling facades it also allows keying-in of bricks and mortar so it’s all locked firmly into the wall.