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KTA-TATOR, INC.
Corporate Headquarters
115 Technology Drive
Pittsburgh, PA 15275
Phone: 412.788.1300
Fax: 412.788.1306
E-mail: info@kta.com

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1-800-KTA-GAGE
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KTA Challenge #11
Answer - Condensation


Photograph 1 - Challenge microphotograph at 50x	Photograph 2 - Condensation on a surface

Challenge 11 (Photograph 1) is a digital microphotograph (50x) of condensation on a surface. The circular area in the center of each droplet is due to the reflection of light. The condensation is more easily recognized in Photograph 2.

Condensation occurs when the temperature of a surface is cooler than the dew point of the surrounding air. When these conditions occur, moisture in the air condenses on the surface. In some cases it is very noticeable such as when condensation forms on the inside of a poorly insulated window on a cold morning. In other cases, it is not readily detected under casual observation, but this "invisible" condensation is of great concern to the painting industry. Condensation on a surface at the time the work is being performed can affect the quality of cleaning, the adhesion of the film, film continuity, and curing.

In order to avoid painting over condensation, in addition to examining the surface visually, most coatings specifications require the use of instrumentation to determine the dew point and surface temperature. Instruments for determining the dew point and relative humidity range from inexpensive sling psychrometers, to more expensive direct read out units. Surface temperature can be determined in a number of ways as well, ranging from inexpensive contact thermometers to more sophisticated and more expensive thermocouples and non-contact thermometers.

Painting specifications typically require that the surface temperature be at least 5ºF above the dew point to guard against the formation of condensation.

All of the instruments needed for determining ambient conditions are available from KTA. KTA can also determine if condensation on a surface prior to curing of the film will effect coating performance.

This one was more difficult than anticipated with only 15% of the responses indicating it was condensation on a surface. Incorrect responses included coating being applied over moisture, moisture coming through the coating, air bubbles in the film, fisheyes, amine blush, solvent entrapment, outgassing, floor grout coating, incompatible silicone or wax particles, resin particles in a waterborne coating, and many guesses associated with blistering. The winner by random drawing is Malcolm Summers of Deborah Services Thailand, Ltd.