Architects: Paint Colorants and Problems with Tints








Paints are generally available as white, tint, and deep and accent bases that can be tinted to various shades and depths by the use of liquid colorants. The level of opaque pigment (in most cases titanium dioxide) is varied to balance the value (degree of darkness or lightness) of the color. The maximum amount of colorant that is added to each base is dictated by the final color required, type and opacity of the particular colorant, and the level of opaque pigment in the base.

Average Compositions:

Base Opaque Pigment* Max Tint
White 2.0 - 3.0 lbs/gal 4 oz
Tint 1.75 - 2.25 lbs./gal 4 oz
Deep 1.0 - 1.5 lbs/gal 8 oz
Ultra Deep 0.3 - 0.5 lbs/gal 10-12 oz
Accent N/A 14 oz
*Note Opaque pigment level varies with manufacturer and paint type.

Many paint manufacturers only supply white, tint and accent bases in their paint lines. This assists in managing inventories and stock in the warehouse and stores.

Problems with Tinted Paints

For the most part, paints using small amounts of universal colorants show no major differences in their physical properties. However, where large amounts are used, properties such as curing time, early and total water resistance, abrasion resistance, resistance to cleaners, burnishing (polishing) and uniformity, are affected negatively.

Universal colorants are materials containing a color pigment dispersed in a blend of surfactants and a liquid (most often a glycol). The level of pigment is dependent on the type, color strength and pigment surface area. Finer (i.e. high surface area) pigments, such as lampblack, are used in lower concentrations than larger (i.e. low surface area) pigments such as red iron oxide. The balance of the material is comprised of surfactants, glycol and in some cases, an extender pigment. The weakness comes from the properties of the surfactants and of the glycol which effectively stay in the paint film longer maintaining water solubility and softness in the dry film.

Exterior paints, containing high levels of universal colorants, can be prone to 'wash-out' from dew or rain for longer periods of time than 'non tints' or low level tints. Another unique problem that can arise is the appearance of surfactant bleed, which appears as a clear or yellowish material on the surface of the paint and can run down onto adjoining surfaces. Although waterborne coatings show the most problems, alkyd types can also be affected. Alkyds most often show lowered gloss levels, and some softness in the film for longer than normal.

Paints made with the color pigments added at the manufacturing stage (although often limited in range of color) offer the benefit of being less sensitive to moist conditions than a strongly tinted base. These should be considered when painting exterior surfaces, particularly those exposed to constant damp conditions, or when application is to take place in questionable weather.

See also What Went Wrong - "Too Much Color?"

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