The quality of a natural stone's final surface polish is dependent on many factors, including the equipment being used, the products employed during the process and the skill of the processor. And in order to maintain an optimum level of quality, Testi Group has dedicated its “Combus” division to work solely on finishing the surface of marble slabs.

Combus works on marble slabs that have been processed on a gangsaw, but have not been further worked. The slabs are calibrated, reinforced as needed and then they receive their final surface polish.

The entire processing line at Combus was supplied by Breton S.p.A. The first step during the process is to calibrate the slabs, which takes place with a 10-head Levibreton line. After the slabs are calibrated, they are ready to move onto the resin-treatment line for whatever reinforcement is needed.

Prior to being treated with the resin, slabs are placed in an oven that is heated to 50 to 62 degrees C to remove all humidity from the material. This allows for maximum efficiency of the resin, and each oven can hold 42 slabs.

Next, a resin product from Tenax S.p.A. is applied to the material. Generally, Combus uses Tenax's Protex sealer, which is formulated to reinforce porous stones and also offers oil protection. After the resin is applied, the slabs then enter a vacuum unit where the resin is forced deeper into the stone. This is followed by transport into a second oven, where the slabs sit for two hours as the resin cures. As needed, a second coating of reinforcement is applied to fill any pores that occurred during the vacuum/drying process. In addition to resin reinforcement, fiberglass netting is applied to the slabs as needed. In general, stones with structural cracks require fiberglass resin netting, although this was not required for the Rosso Verona marble used on the Banco Popolare project.

After the resin cures, the slabs receive their final polish on a 14-head Levibreton polisher from Breton S.p.A., and they are packaged for shipment to their destination. On average, Combus processes one slab every two minutes.