My next model will be a soap factory. In my layout era (1939) soap factories were in some ways similar to chemical factories. The ingredients in soap at that time were kind of nasty including such wonderful ingredients as various acids (auric, myristic, palmitic, steric, oleic, linoliec, and ricinoleic), sodium, potassium, oils, fats and alkaline solutions - fun stuff. My wife knew of neighbors who in the 1960s would make their own soaps.
Below is a 1916 photo of the Procter & Gamble soap factory located in Ivorydale, Ohio. It is significantly larger than what I will build but there are some elements I will be using such as a power plant and chemical tanks.
The process of soap making in that era, while it varied to some extent, in general it started with boiling a mixture of animal fat or fatty oils with a one or more of a variety of acids. When the mixture was properly blended, the resulting material was placed in some form of drying environment ranging from racks to drying tunnels. The soap was then cut into bars for packaging and sale. There were of course other processes using other ingredients. The soap products of the time had some fanciful names - one of my favorites being Goblin Soap with the image of a little goblin on the package.
As usual, I drew a rough sketch of what I intend to build which essentially consists of three buildings, the center being the power house. It will be against the wall so presumably the factory extends to the rear through the wall. Below are some soap factory diagrams.
Above is a cross-section of a soap factory plant.
And here above is a floor plan of the same plant.
And above is a general view of a small soap factory with cylindrical soap pans.
This is a photo of the tops of soap pans.
Above is a photo of soap driers.
I have started constructing two of the three buildings. More later.