Measuring standards of gloss for polished concrete through technology

Measuring the gloss level
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.

GLOSS LEVEL TABLE

LEVELGRITSHEEN LEVELMINIMUM NO. OF ABRASIVE PASSESAPPEARANCEGLOSS READING

Below 100 None to very low 4Flat. Floor has little if any reflectivity a 200 to 400 Low to medium Satin or matte appearance with or without slight diffused reflection. 40-50 3 800 and higher Medium to high Semi-polished. Objects being reflected are not quite sharp and crisp but can be easily identified. 50-60 4800 and higher High 70 Highly polished. Objects being reflected are sharp and crisp, with mirror-like clarity.60-80

Aggregate exposure
Aggregate exposures range from “cream,” with very little exposure (Class A), to large aggregate exposure up to ¼ inch (Class D). Because there is very little cut depth, a cream exposure will not remove existing blemishes or surface imperfections in the concrete. A Class D aggregate exposure is very attractive, but requires more aggressive grinding, which can increase the cost of the project and expose pits or divots in the concrete that will need to be filled. Note that varying degrees of sand and aggregate exposure, not to mention small pits and divots in the surface, can significantly influence gloss readings.

AGGREGATE EXPOSURE TABLE

CLASSNAMEAPPROXIMATE SURFACE CUT DEPTHAPPEARANCE A Cream Very little Little aggregate exposure. B Fine aggregate (salt and pepper finish)1/16 inch Fine aggregate exposure with little or no medium aggregate at random locations. C Medium aggregate 1/8-inch Medium aggregate exposure with little or no large aggregate exposure at random locations. D Large aggregate1/4 inch Large aggregate with little or no fine aggregate exposure.