Just when we feel we know enough about a material, it is time to recheck – there could be aspects we took for granted and erred in its application. Many of us are so familiar with marble that the danger of some unknown ignorance costing us dearly is always around! This awareness dawned even as I was writing on marble, for the more one wrote, I realized that more issues still remain to be discussed.
Ask anyone about the most commonly known aspect of marble – the immediate answer could be about polishing. The bright appearance achieved by polish has been among the reasons for the popularity of marble. The simpler and cheaper method is wax polish, done with 3 rounds of polish with carborandam stone and finished with wax application.
The more common approach is called mirror polish, seven rounds of polish with carborandam and final tin oxide buffing on top. The wax reflects less light and wears fast, but the mirror polish shines better, hence the latter is worth the time and money it demands.
While pre-polished marble slabs can be organised, for the best results, they need to be polished at site, during the construction.
The base layer for marble floor should be a good mix of concrete, evened and leveled with 1:6 mortar on top around 1 inch thick. Cement slurry acts as the final base layer and the joints are better finished with matching pigmented material especially available for the purpose.
In perfectly cut and laid marble, joints can be finished with minimal visibility. Epoxy joints reduce the possibility of white cement joints gathering dirt, but are slightly costlier. Due to its high surface density and particle characteristics, marble can be slippery after fine polish, especially in bathrooms, staircases and kitchens. It will be safe to avoid them in such areas, avoid tin oxide finish or ensure alternate anti slippery finishes.
Grains & patterns
Matching the grains and patterns between adjoining slabs are a much talked about expectation in marble floor, which can be ensured by collecting all slabs from the same boulder and placing them carefully. White marble slabs can be laid over white cement slurry, to increase the sense of whiteness in the finished floor.
Marble is known to get stains, which can be partly or fully removed by applying wet marble powder or by polishing. No acids, chemical cleaning liquids, alkalis or detergents should be used. The water in the base mortar gets partially absorbed by the marble, it being a porous material, reducing mortar strength. Immersing the slab in water for few hours before laying helps reduce this absorption. While marble is a natural material, hence eco-friendly, it is not among the low energy options.
Considerable energy goes in the quarrying, sizing, cutting and transporting process. There are also wastages at quarry sites. Once brought to site, it demands many rounds of polishing, further consuming energy accordingly.
However, the saving grace lies in marble being a natural material that lasts long.
(The writer is an architect, working for eco-friendly designs and can be contacted at varanashi@ gmail.com)