Accurate Paint Colors Using Ultra Precision Scales

By Author: Mel Joelle
Total Articles: 4328
Comment this article

You bought that brand new Ford Mustang because you really liked the Candy Apple Red color on that car in the lot. On the opposite side of the country, someone else bought another Mustang in the same color. If you were to park the two cars next to each other on the Interstate rest stop, your eye would not be able to distinguish any difference between the colors of the two automobiles. In fact, every single Candy Apple Red car of that model year would be identical in color.

Such precision matching of color is not at all an easy task. The human eye is an exquisitely precise optical instrument. It has the capability of differentiating between even very small differences in color, shade, hue and brilliance. The automotive paint must be manufactured with incredible consistency to achieve this result.

Paints include many different components. The purpose of the paint will dictate some of those ingredients. One type of component that contributes greatly to the final color of the paint are the pigments used. There may be natural pigments that include different types of talc, silica, calcium carbonate and clay. Some of those ...
... same types may be manufactured, instead of natural, to enhance some of their properties. Other types of pigments are used to provide protection from sunlight or other environmental conditions. Fillers are added to adjust the thickness and volume of the paint, allowing different types of methods to be used during the painting process.

Binders are added to the paint for proper adhesion to the surface that will be painted. Generally, the binder will be some type of a resin, such as polyester, epoxy, oil, acrylic or polyurethane. Solvents and other additives round out the list of paint ingredients.

Each and every one of these ingredients must be mixed in a very precise ratio to achieve the desired consistent result. Although it may seem that the best method for dispensing each item would be by volume, it becomes quickly apparent that this is virtually impossible. Some of the ingredients may be very viscous liquids. Others may be powders or slurries, making volume measurements inaccurate. Weight must be used instead.

Certain paint ingredients are just a very, very small percentage of the overall volume, but they have an inordinate effect on the final product. This can certainly be the case of pigments. In considering the final color of Candy Apple Red, one can understand that the amount of red pigment must be measured with very high precision. Therefore, the industrial scales used for this purpose must have a large enough capacity to weigh the entire batch of paint, but must also have extremely high resolution in order to be able to accurately weigh the pigments and other micro ingredients. Depending on the volume of the batch of paint, the digital scales used may be bench scales, or drum scales or platform scales.

Most electronic scales are not suitable for this purpose. The most common industrial scale technology is based on the use of strain gage load cells. While these are fairly inexpensive, they have limited levels of accuracy. A standard bench scale or platform scale with a capacity of 100 lb may have a resolution of .02 lb. The best industrial units available may increase this resolution to .01 lb. When the total amount of a certain color pigment may only be in the range of 1 or 2 lb, it is evident that these scales will not be appropriate.

A new technology in industrial scales is offered by Arlyn Scales in their line of Ultra Precision Scales providing Surface Acoustic Wave, or SAW Scales. These electronic scales utilize a semiconductor transducer to provide up to twenty times the resolution of strain gage scales. The SAW Scale with a capacity of 100 lb provides a resolution of 0.001 lb. There is now enough accuracy to accurately add each of the ingredients into the paint. These paint scales are available with capacities ranging from 5 lb up to 200 lb. A larger, platform scale version of this technology is also available with capacities starting at 200 lb and ranging up to 500 lb.

An additional feature of the entire line of SAW Scales is the very high overload specification. While other electronic scales may be damaged if a paint bucket is dropped onto the scale platform, the Ultra Precision Scales offer a maximum overload of 500% of the capacity of the scale.
Click here to read the rest of ultra precision scales. If you enjoyed this article, you also might like our other stories about paint and ultra precision scales.