Thermopel

Center*Star Additive Heat Resistant Paint

Posted on February 21, 2012 by Thermopel Paints

Center*Star, Inc. has developed an additive that, when added to paint, results in significant reduction in thermal conductivity. The additive was originally used as an admixture in the development of durable, spall resistant, concrete for use on F35 landing strips. The heat reduction characteristics of the concrete led to the hypothesis that the additive could also be used in other applications.

The additive was blended with commercially available paints and tested using a variety of protocols. Based on these initial tests it was determined that up to five percent of additive could be blended with paint with no noticeable effect on the finished surface. At dosages greater than five percent (by total weight) some variation in surface texture was observed.

Initial testing involved temperature comparisons of identical metal panels painted with a readily available acrylic primer. The paint was roller applied. One panel was coated with only the paint, and another was coated with the paint plus five percent additive. Heat was introduced using a radiant heat lamp.

The test results showed that the additive was capable of reducing the transmitted heat so additional testing was conducted using a higher heat source.

MAPP gas was used as the heat source for high temperature testing. MAPP gas has a rated temperature of 5300 degrees. Although not conforming to any ASTM or ISO heat testing protocol, MAPP gas has the advantage of being relatively inexpensive and produces temperatures far in excess of that required for ISO 1182 testing.

One disadvantage of MAPP gas is that the hydrogen component can cause brittleness or crystallization. That is the primary reason it is not used for welding.

The heat test was conducted on cast iron water meter covers. The thickness of these plates was 0.25″. Both coated and uncoated specimens were tested. The coated plate had a 70 mil layer of Induron® Aquanaut acrylic primer with 5% (by weight) of Center*Star additive.

During the test, temperature readings were obtained using an infrared thermometer. The “high limit” capability of this device was 1400 degrees and during the test this surface temperature was exceeded. A reasonable assumption would be that temperatures of 2500-3000 degrees were attained on the test surface.

Temperature readings were recorded at 30 second intervals until the backside temperature of the test specimens stabilized. The total test time was 5 minutes 30 seconds.

The following chart graphs the time vs. temperature readings for both the coated and
uncoated cast iron specimens.

As shown by this graph, the heat transmission of the bare metal plate was significant. At the end of the test the backside temperature was over 600 degrees and was still rising. The temperature of the coated specimen reached equilibrium at about 3-1/2 minutes. The maximum temperature recorded was slightly over 200 degrees which is more than 400 degrees less than the uncoated plate.

Encouraged by these results, the Center*Star team decided to purchase more sophisticated monitoring and heat source equipment. It was decided to use a commercial knife making forge as the source for a controlled, constant temperature heat source. The temperature of this forge could be closely regulated by adjusting the two propane burners used as the heat source.

Laboratory quality temperature probes, thermal logging instrumentation, and computer software replaced the hand held infrared temperature monitors used in earlier experiments. With this equipment, we could be assured of having accurate data to evaluate the effectiveness of the Center*Star additive.

Using the advanced instrumentation, testing was continued with both metal plate panels and solid core specimens. These tests were designed to closely approximate the conditions under which ISO 1182 and SOLAS/IMO A60 laboratory trials are conducted.

Since these initial forge tests, modifications and improvements have been made to the testing apparatus to reduce inconsistencies and provide better data. Testing continues on a daily basis but enough information has already been gathered to prove that the Center*Star additive can consistently reduce heat transmission.

A representative graph of our latest test data is shown below.

The anomalies in the data chart lines were caused by excessive wind gusts during the tests. The forge has since been modified to prevent outside air disturbance. As shown by this data, the additive enhanced paint reduces radiant heat throughout the temperature spectrum but it seems to perform even better at higher temperatures. At the end of the test shown above, the temperature reduction was 23 percent.

Conclusions

Paint with the Center*Star additive can produce a significant reduction in thermal conductivity. The additive is easily blended in all paints and does not impair the finished surface characteristics.

Recommendations

• Continue testing using a variety of substrate materials, paints, and thicknesses.
• Determine the most appropriate base paint for the required application, considering the level of protection needed and associated costs.
• Conduct formal testing through an internationally recognized testing organization capable of testing to ASTM, ISO, SOLAS, AND IMO standards.

Want to know more about the application of your Thermopel paint? For fast and friendly customer service, contact our Support department at Induron Protective Coatings:

1.800.324.9584