How to achieve different levels of sheen on a polished floor by Anne Balogh, ConcreteNetwork.com Columnist
At a level 3 polish, your concrete floors will really begin to shine and clearly reflect side and overhead lighting.
Depending on the diamond grit you use to polish a concrete floor, you can achieve different ranges of polish and different levels of sheen, from matte to a glassy mirror-like finish. These ranges are typically categorized in levels ranging from 1 through 4. For coarse grinding, you'll generally start out using diamonds embedded in a metal matrix. As you begin to polish the floor in successive passes, you'll typically switch to finer diamond abrasives bonded in a plastic or resinous matrix to achieve higher degrees of shine. Here are the four levels of polishing and the degree of shine you can expect to achieve at each level. (Source: Bob Harris' Guide to Polished Concrete)
A level 1 polish usually can be obtained by stopping at the100-grit resin bond. When you look directly down at the floor, it will appear somewhat hazy with little if any clarity or reflection.
A level 2 polish is obtained by stopping at the 400-grit resin bond, producing a low-sheen finish. When you look directly down at the finished floor and at a distance of roughly 100 feet, you can start to see a slight overhead reflection. This grit level produces a low-luster matte finish.
A level 3 polish is achieved by going up to an 800-grit diamond abrasive. The surface will have a much higher sheen than that of level 2 finish, and you'll start to see good light reflectivity. At a distance of 30 to 50 feet, the floor will clearly reflect side and overhead lighting.
This level of polish produces a high degree of shine, so that when standing directly over the surface, you can see your reflection with total clarity. Also, the floor appears to be wet when viewed from different vantage points. A level 4 polish is obtained by going up to a 3,000-grit resin-bond diamond or by burnishing the floor with a high-speed burnisher outfitted with specialty buffing pads.
Once you have completed the entire polishing process, you'll be left with a beautiful, shiny surface. But how do you accurately assess the degree of shine, other than by simply visually inspecting the amount of light reflectivity or clarity of the polished surface? Today, specifications for polished concrete are now including specified gloss readings, determined using gloss meters (see table). Gloss values express the degree of reflection when light hits the concrete floor surface, and range from 20 to 30 (low gloss) to 70 to 80(high gloss). For example, a gloss value around 30 will generally produce a low-satin sheen while a value of 80 will produce a very high shine, especially after high-speed burnishing. You may want to consider investing in a gloss meter as you begin to tackle larger polishing projects.
Dull or matte look
Shiny look that is slightly cloudy
High sheen with clarity
Floor has little if any reflectivity.
From a distance, floor will start to reflect images from the side. Floor has a whitish or cloudy appearance.
At a distance of 30 to 50 feet, the floor reflects from side to side. Floor starts to shine, but has a slightly fuzzy appearance.
Looking straight down on the floor, it clearly reflects overhead and side lighting. The floor is very shiny and looks wet from a distance.