Spot test of wood surface temperatures

Preliminary spot test of the temperatures of bare wood, latex paint, and lime based whitewash (CACO3)

5/17/06 by Anthony Watts, Chico, CA

Click thumbnail pictures for larger ones

Test setup in full sun. Three slats of 1x4 pine, 2 feet long each, bare wood in the center as a control, latex on the left, whitewash on the right.

Methodology: Whitewash was mixed after conferring with Chemist Richard Godbey of the Chemical Lime Company in Henderson NV and after reading a paper he authored on the history and home creation of whitewash which you can read here http://www.lime.org/BLG/Mold.pdf (PDF)

Pictures: Materials, Mixing Whitewash, applying whitewash coat 1, coat 4 after 24 hour curing

Slats were all cut from same plank, chosen to be as knot free as possible, cut to exact same size, 2 ' long, and spaced equidistant on the frame.

Measurements were taken 3 times with IR thermometer shown below, at1:50 PM, 2:10PM, and 2:20 PM PST to be sure results were repeatable. What you see below is the 2:20PM spot test.
 

Device used to measure surface Temperature, A Fluke model 561 HVAC Pro IR thermometer, handheld with laser dot sighting of measurement target

Temperature of bare wood, this represented average of several scans. The temperature was 102.6 degrees F

Temperature of Latex Painted wood, the leftmost slat temperature 88.2F

Temperature of Whitewashed wood, the rightmost slat temperature 82.5F

Summary:

Temperature difference between bare wood and Latex painted wood was about 14 degrees F

Temperature difference between bare wood and whitewash painted wood was 20 degrees F

Temperature difference between latex painted wood and whitewash painted wood was 5 degrees F

Next Test: time series temperature over several days measured by NIST calibrated data logging thermometers compared to ambient aspirated air temperature.