Ask facility maintenance managers how glossy their floors are and you will get as many answers as there are ways to wax and polish floors. This is because everyone sees gloss differently.

But now there is a way to standardize gloss measurements.

Whether you are maintaining vinyl, marble or any other shiny surface, a gloss meter can help you check the quality of your finishes and set standards.

In order to understand gloss, you must first know about some of the principles of optics. When light falls on the surface of a tile, a portion of the light is absorbed and a portion of it bounces off. The light that bounces off is called reflected light and can be classified in two different ways:

1. Specular reflection: This is the light that is reflected at the same angle as incoming light. It is sometimes called mirror image.

2. Dispersed reflection: This is the light that is reflected in various directions.

Reflection is a combination of the two classes of reflected light.

On highly polished surfaces such as marble, granite, glass and porcelain, the ratio of specular light is high and dispersed light is low. This is what is called high gloss.

Surfaces such as vinyl tile, honed marble, or etched glass have a low ratio of specular reflection which results in low gloss. This is sometimes referred to as a "matt finish,".

Gloss is defined as the intensity of light reflected in the mirror image direction (specular). The best way to actually measure light intensity is to use a photodetector, a device used for detecting and measuring the intensity of radiant energy through photoelectric action. A gloss meter contains a photodetector.

Gloss meter operation

A gloss meter has a photodetector and light source. The light is directed at the tile surface at a specified angle and then reflected off the surface and back to the photodetector. The angles at which the light is reflected and received are critical. There are five different angles that can be specified: 20, 45, 60, 75 and 85 degrees. Most gloss meters use the 60-degree angle because of its ability to measure both high and low gloss levels.

The numerical value obtained is the result of reflected light bouncing back to the photodetector. The photodetector is attached to an amplifier-rectifier and transformed into a signal that is proportional to the gloss. The signal is then converted into a digital readout which can then be measured.

The number obtained on the gloss meter is linked to the reflective quality of the tile being measured.

Gloss readings

On marble and stone the gloss reading can be an asset.

Measurements can be taken as the stone is honed and brought to a polish. The gloss meter also can be used as a tool to determine when the surface is ready for the next polishing step, or as a diagnostic tool for determining aging and defects on the surface. Gloss readings on marble can vary significantly. Several readings should be taken to get an average.

Most vinyl floor tile is cleaned, stripped and waxed frequently. When this occurs the gloss meter becomes an important tool to ensure uniformity. A visual inspection makes it hard to establish standards. To make effective and precise measurements, a gloss meter should be used.

Monitoring practices

Gloss meters should be used on a daily basis to monitor your maintenance practices. To use your gloss meter, remove the protective cap, place the meter on the tile and press a button. It is best to take 10 readings per 500 square feet.

Also try to take a reading in the same spot every time and pay special attention to high traffic areas. After you have taken daily readings for one month you will have established good base readings that should become the standard.

The newly established standard can alert you to when the floor needs to be stripped or, in the case of stone, when refinishing is needed. When gloss readings fall off or become too low, you know the surface is losing gloss.

Sometimes a gloss meter can act as a marketing tool. If you are a contractor, when you walk into a customer's building and start taking gloss readings, you turn a simple maintenance or restoration evaluation into a scientific test. This conveys to the customer that you know what you are doing.

Frederick M. Hueston is president and owner of The National Training Center for Stone & Masonry Trades, Winter Park, FL.

For more information on this article, please go to www.facility-maintenance.com and use the following keywords in an article search: gloss meter, floor finish, photodetector, specular reflection, dispersed reflection.