The Traditional Way Of Hand Polishing Marble
Author:vian Date:2/17/2009 6:49:34 PM Read:446
Forty years ago when I started out my career all marble edge polishing was done by hand. Today such work is done entirely by machine but there are still circumstances where hand polishing would be a useful skill to know.
Traditionally edge polishing was considered a separate semi-skilled trade. These polishers spent their whole working day rubbing hundreds of feet of marble edges and would develop strange physical deformities, bulging shoulder muscles and a thumb that would curve back and touch their own wrist were the most common!
The process would start once the edges to be polished had been identified, large areas of marble slabs, for instance the cladding on commercial buildings would be laid out on huge benches and pattern matched. The exposed edges that required polishing perhaps hundreds of feet, would be identified and marked.
One at a time each slab would be propped upright against a bench with the edge to be polished uppermost. Just to hand would be a bucket of water, a sponge and a rag cloth.
The work was carried out using various grades of carborrundum stone blocks and to start would be a coarse 60 or 80 grit stone. This would be the longest stage of the work as the edge of the marble would have quite deep ??wheel marks?? left by the diamond saw blades from the cutting. The stone would be dipped into the water and then rubbed evenly up and down the edge of the slab always keeping a heavy and steady pressure on. The rough corners of the marble would be also rubbed off to create a small flat corner called an arris.
Every now and then the marble had to be dried to check on progress, this was achieved by whirling the rag in the air above the work. This is still the best way of drying large areas of wet stone by the way!
Once all of the wheel marks and other deep scratches were removed with the 60 grit he would move on to the second stone, this time a 120 grit, just a bit finer than the previous stone. This stone would be used until all of the scratches from the previous grit had been removed completely and replaced by a new layer of finer scratches.
Polishing marble is in fact the process of wearing down the surface with finer and finer scratches until the scratches are no longer visible to the naked eye!
This process continues through at least six different grits of abrasive down to a 500 or 600 grit. The final stone used was a very fine block made by the polishers themselves from ultra fine carborundum dust and marble glue, and strangely called snake!
At this point the marble surface is still not highly polished. It has just a very smooth honed finish. The final stage is achieved with a hard block of felt and a cocktail of various polishing powders, the most commonly used were putty powder, pumice powder and oxalic acid. One or all of these would be used wet or just damp to provide the final gloss.
The most obvious advantage of hand polishing is that this process does not create clouds of dust, as the work is carried out wet, This means that unlike dry machine polishing, there was little serious health risk to the polishers. The quality of the finished polish was also superior to machine polishing leaving a higher polish, smaller arrises and a flat surface.
However, hand polishing is a seriously slow and laborious process. Machine edge polishing is much quicker, and within three or four years of the appearance of edge polishing machines the art of hand polishing marble had all but disappeared.