Glossed in Translation

Glossed in translation

Gloss is a qualitative term used to describe the luster of paint films.  As with all visible matter; light, texture, gloss & color all play a role in what the viewer sees.  Gloss levels are as much a part of a paint film as are color and resin.  Though gloss is not a color, the same color is viewed differently as gloss levels change.  Gloss refers to the intensity of reflected light, independent of color.  When broken down quantitatively, gloss is measured in units ranging from 0 (dull) to 100 (mirror-like) when measured from an angle of 60° from perpendicular for all films, low gloss films often site a second viewing angle of 85°.

At a gloss for words

Instead of citing gloss units when describing paints, manufacturers have chosen terms including "matte", "flat", "eggshell", "satin", "pearl", "semi-gloss", "gloss", and "high-gloss" that refer to gloss measurements between a given range.   These terms are then used when describing a product.

• Make special note of the overlapping terms.  One manufacturer’s “satin” product may be lower in gloss than another manufacturer’s “eggshell” because of the range alloted in terminology.  This makes product comparison via the paint label alone subject to misinterpretation.  To be certain, reference the product data sheet provided by the manufacturer, as it will list the actual units measured.

How could you be so dull?

If you look at a paint film up-close, you will realize that surface roughness leads to duller films.  This surface roughness is created by pigment and fillers distributed in the paint film that collect near the surface.  Low gloss coatings have less resin at the surface than necessary to completely encapsulate the pigment, as a result this pigment will cause light to diffuse, thereby reducing its intensity.  This explains why flat coatings are not scrubbable - any disturbance to the surface of the film will cause a shifting in the loose pigment particles; much like rubbing your hand along a velvet or suede textile.  High gloss coatings have an abundance of resin at the surface to encapsulate all pigment and filler, providing a film which can be washed and scrubbed without experiencing a change in appearance. 

PVC (Pigment/Volume Concentration) is the measurement of pigment and filler particles in a given volume of paint.  As the PVC is increased by the paint formulator, the gloss reading decreases accordingly.  Each paint film has a CPVC (Critical Pigment Volume Concentration) - this is the point in which the paint film is actually porous and the integrity of the film is compromised.  Most “low quality” paints have PVC levels which are at or above the CPVC - there are exceptions in which high quality paints also have high PVC levels.  Wood stains are above the CPVC, that’s why they require a varnish over them.