How do you polish dull marble and granite
“To restore” means to bring something back to its original condition. When dealing with small scale marble restoration interventions, it is often necessary to work on a small marble part, leaving the non-damaged part unaltered. If the part to be restored is located on the surface – and is therefore? visible – the reparation work must be performed flawlessly, so that no sign of intervention can be seen. That’s why knowing how to replicate the same degree of finishing as the original surface on the area of intervention is of foremost importance. Such goal can be accomplished by faithfully replicating the process through which the original finishing was produced.
So, first of all we will have to find out how things are carried out at the factory level. We will discover that, at an industrial level, the manufacturing of stones differs depending on their nature and mineralogical composition. In light of such discovery, for our convenience, we will roughly divide the stones into two broad categories: “marble” and “granite”. That does not necessarily entail that all the stones included in the “marble” category are strictly marbles, and that those included in the “granite” category are st?rictly granites. Categories simply help us determine the surface treatment method we will need to use for the recovery.
In the industrial world, the distinction between materials – with the purpose of grinding and polishing them – is intricate and complex. However, for our purpose, the simplified marble/granite dichotomy works well enough.
Agglomerated marble is a carbonate material sensitive to acids
Two different categories for stone work
Rocks with high carbonate content (marble, limestone, limey sandstone, travertine, onyx), i.e. stones mainly composed of calcite and/or dolomite belong to the “marble” category. We will explain the meaning of the term “carbonate” later.
Non-carbonate rocks belong to the “granite” category: stones with low carbonate levels (such as serpentine and green marble), and stones that have a predominant silica SiO2 content (such as granite, quartzite, siliceous onyx).
Depending on the category, stones undergo a different sanding/polishing process. The process is carried out with solely mechanical means for the “granite” category, and with both mechanical and chemical means for “marbles”.
N.B. For greater accuracy we must point out that, apart from natural marbles, all composite materials with carbonate as main component (agglomerated marble, Venetian-style marble terrace floors etc.) are included in the “marble” category.
Note that artificial materials such as the so-called “quartz”, “okite” (more generically known as quartz resin), “Corian” (or similar materials known as cultured stone in English-speaking countries) are not carbonate materials. They must therefore be included in the “granite” category.
Corrosion marks reveal the carbonatic nature of the stone