Fingerprints, Dark Marks and Stains
The most popular granites to hone are the darker stones such as Absolute Black. Dark stones tend to be harder, denser and less prone to surface marks. Unfortunately, they also show off more surface stains once they are honed.
Honing dulls the color of the stone, giving it a more natural appearance. When the stone becomes wet, either through water, oils, juices or fingerprints, it darkens. These surface stains can be removed by frequent washing with stone cleaners. If an impregnating sealer has been applied to the stone, it must be removed and a surface sealer put in place that will uniformly darken the stone to minimize the appearance of surface stains.
Nearly all granite slabs are polished before being shipped to the fabricator. This is because polished slabs make up the bulk of sales. If a customer requests a honed stone, the polished finish is then ground down and removed with honing powder.
In the case of some stones, the grinding that takes place to polish the granite leaves behind grind marks, or swirl marks in the stone. Honing does not grind the stone down to the same degree that polishing does. Therefore, if there are grind or swirl marks present that the reflective surface of the polished stone was hiding, honing will reveal them. The result will be subtle swirls or machined marks on the surface of the granite.
More Visible Pits
Not all stones sold as granite have the same mineral or structural make up. Some stones are softer, more brittle and have a more open mineral structure. These stones are typically lighter in color, may contain large flecks of mica or quartz and contain numerous small pits or pin holes in their surfaces.
Polishing these stones hides the pits because light reflects off the polished surface, which in turn reflects away from the pits. Honing the stone will reveal all the surface pits of the stone. For some stones, there will be only a few pits, but others will have multiple small holes and pits visible once the honing has taken place.
Uneven Surface Finish
Just like some stones have many small pits in their surfaces, other stones have small fissures or are made up of many softer materials, including many overlapping bits of mica. Stones such as Labrador Antique, which have an iridescent finish when polished due to the surface structure, hone with an extremely patchy finish. The mica patches still reflect some light while the harder surrounding minerals absorb it. This results in an uneven finish that shows small fissures or breaks between the minerals.
These marks are only cosmetic; it will not affect the structure of the stone, but fingerprints and other stains can make them stand out more.