Once upon a time, the use of paint was limited to two specific purposes: paint existed either as protection for a substrate or as decoration.   In recent decades, new additives and mixtures have yielded paint that is capable of not just protection or decoration, but that also has function all its own.

Last week’s Chemistry Corner focused on paint that actually cleans itself.  This week we will be discussing paint that changes color with temperature variance.   While paint that changes color is useful for aesthetic purposes, it also serves as a useful tool in the workplace where decoration is not its core purpose.

Image Courtesy of Electronics-Labs.com

Paint that changes color with a change in temperature is known as thermochromic paint. Thermochromic paint is produced either by using liquid crystals or leuco dyes to manipulate the paint’s appearance as a result of outside variables.  Thermochromic paint originated in the 1970’s, but new uses are being found every day.  This innovation in paint chemistry is used on everything from tea-kettles to baby bottles.   Over the years, breakthroughs have been made that allow for scientists and chemists to create paints that appear to be very specific colors within very specific temperature ranges, as opposed to simply changing from one color to another at an unspecified inflection point.    The applications of such technology are near endless.

For example, this type of paint is used on cars to give off a custom look as the car appears to change color depending on the temperature of the air around it.  Some custom car outfitters offer customers the chance to have their break pads appear black when they are cold , transforming them into a  bright red or orange hue when the pads are heated up through use.  In the video below, paint color is manipulated by the addition of warm water to a Nissan painted with thermochromic color-changing paint.

While the visual effect is appealing to some, the practical application of such paint is significantly more important.   For example, pipes in a refinery can be painted with paint that is blue when under a certain temperature, but changes to red at higher temperatures.   Such paint can indicate an unsafe fluid temperature level and directly result in improved efficiency for the refinery  and improved safety for the on-site workforce.  Thermochromic color-changing paint can also be used to signal when a tea-kettle is hot enough to use or when a  specific type of drink has been cooled.

Image Courtesy of Hali Pigment

For the professional painter, thermochromic paint offers not only new opportunities  but also significant challenges as well.  Testing thermochromic paint with standard drawdown cards or paint swatches can be challenging, as the test temperature must be regulated. Furthermore, coating thickness must be measured based on specific quantifiable readings instead of visual validation of color, gloss, and clarity, since thermochromic paint does not exhibit the same static visual properties as standard paint.   Using color-changing paint in a commercial or industrial setting requires increased diligence by the paint supplier and the painter to make sure the correct paint is applied at the proper thickness to produce the desired result.

Scientists work daily to increase the usefulness and functionality of paint.  Different additives and mixtures produce new products with myriad uses for the paint professional and consumer as well.   Click here to learn more about the additives offered by BYK and the amazing new innovations in paint chemistry available right now.