Plaster of Paris: From Medicine to Building

I first heard about plaster of Paris (POP) when I was still quite young and I only came across it in relation to medicine. While playing in our youthful exuberance, one of us, a neighbour, got his hand fractured and had to be rushed to the nearest hospital for immediate medical attention. He came back with a rather huge and whitish material plastered all over his leg. They called the substance POP.

I came across the word 'POP', again during my secondary school education, in a chemistry class to be precise. The teacher was busy discussing the chemistry of calcium while impassantly mentioning that hydrated calcium sulfate is utilized in bone rehabilitation as plaster of Paris (POP).

Just recently, the words popped up again in a building construction sense. Obviously, the vogue now is to use plaster of Paris to make building ceilings instead of the usual asbestos that has become the household name. Change is a constant thing, they say.

I was lucky enough to have witnessed the process of using plaster of Paris as ceilings for buildings. The pop artisan was invited to value the work and he estimated the total quantity of materials that would be required in addition to their workmanship. According to them, the standard is to charge about $10 per square meter of the ceiling.

After successfully negotiating, the artisan went and brought in some materials. The major material is what is known as cement plaster. It looks in every way like cement except that it is white instead of the characteristic ash colour of cement. The cement plaster is bagged the same way the normal cement is bagged - 50 kg per bag. According to the artisan, a 50kg of cement plaster went for $12 approximately.

^{Mixing cement plaster with water}

Another material bought along with the cement plaster is fiber, popularly known as fillas by pop artisans. It is useful in making casts for ceilings. For every bag of cement plaster, there is a recommended amount of fillas (in kg) for quality products.

The materials were brought and work commenced. The first stage was to make casts for the ceiling using a casting board of applicable dimensions. The board was placed on a raised platform and lubricated with a lubricant. Thereafter, some amount of cement plaster was measured and mixed in a measured amount of water until a fine paste was formed. The paste was carefully spread on the lubricated board with a measured thickness and some quantity of fillas was spread on the paste accordingly before another paste was added to cover the fillas.

^{The casting process}

The cast was then allowed to set for some minutes before being separated from the board. The lubrication made the separation of the cast from the board quite easily. The same routine was followed until all the casts required for the ceiling were completed. Next was to start hanging the casts to the ceiling accordingly.

^{A finished cast, ready to be hung}

In order to hang the cast across the ceiling, a temporary scaffolder had to be constructed so as to make reaching the ceiling easier. Medium-size tornado nails were nailed across the ceiling level around the walls of the apartment and the casts were hung one after the other according to the pre-selected design for the ceiling.

^{hanging the casts according to a pre-selected design}

^{Work at an advanced stage}

The casts were hung one after the other using binding wire and the joints between two casts were filled with a thick paste of cement plaster. Overall, it was an educating experience for me as this was the first time I will be witnessing such an architectural work.

Apart from cement plaster, there are other forms of plaster of Paris such as gypsum plaster and lime plaster. They are utilized in different industries. Cement plaster is not limited to just being useful in the construction of ceilings. It is utilized in wall screeding and other decorative artworks

Advantages of using POP in construction works

Using POP in construction works offers a whole lot of advantages. Cement plaster can be used to coat walls before painting in order to protect the paint from fading out easily. Utilizing POP in building constructions also aids the fireproofing of the building because POP is fireproof on its own.

Thank you all for reading.