How to Make Color-Changing Paint at Different Temperatures
Things You Will Need
Acrylic Medium (see craft stores)
Thermochromic Pigment Paste/Powder (available online)
Bear in mind that traditional color-mixing rules apply; if, for example, yellow pigment is added to blue paint, the resulting paint will be green when heat is applied.
When buying pigment, either in paste or powder form, shop around on the Internet. There are several different suppliers offering different varieties of paint at different prices. There are metallic paints available that are slightly more expensive, and primary colors will always be cheaper.
Be aware that acrylic paint is exceptionally hard to remove from clothing and other materials. It is suggested that you wear protective clothing and mix your paint outdoors. Remember also that you are dealing with chemical compounds as well as paint, so wear gloves and ensure you are working in a well-ventilated area.
Paint that changes color at different temperatures is known as thermochromic paint. The color change occurs as the compound structure of pigment molecules within the paint react to the increased temperature, which means that the paint absorbs or reflects light differently. With most pigments, this color change occurs at temperatures above 81º F and returns to normal when cooled. There are two methods of creating thermochromic paint, one involves the use of liquid crystals, and the other uses leuco dyes combined with chemical compounds. As thermochromic paint is a relatively new invention requiring in-depth scientific knowledge, the best way to make it is to purchase pre-made compounds and combine them with paint.
Combine desired amount of acrylic paint with acrylic medium in mixing bucket, approximately one part of medium to 10 parts acrylic should suffice. Stir to achieve a smooth consistency.
Mix in thermochromic paste/powder and stir--initially add just a small amount (5 ml of paste/1 tsp powder).
Paint a test sample on a piece of scrap material: allow it to dry.
Heat test sample to over 81º F using a hairdryer; check the temperature with a thermometer.
If the desired color change is not achieved, add more paste/powder to mixture; stir and repeat process.
Once your test sample displays the correct color change, proceed to paint the designated object. Paint one coat, without allowing painted areas to dry before the remainder is completed; otherwise the color change will be uneven.