Thickness and color testing equipment helps maintain aesthetic quality, protects products and assists in lowering cost and waste. Associate Editor Diana Mirel discusses new technology for testing equipment.

High-tech quality-control equipment can help companies maximize coating usage and boost their bottom lines. In the past, costly and complex color and thickness testing equipment primarily catered to larger companies with bigger budgets. However, in the past five to 10 years, quality-control testing equipment has decreased in price while advancing technologically, which makes purchasing the equipment more practical and affordable for smaller companies on tighter budgets.

“Gauges are very affordable now,” says James Fusco, technical coordinator at Paul N. Gardner Co. (Pompano Beach, FL). “Mom-and-pop paint and body shops around the corner can afford testing equipment now.”

In these tight economic times, competition forces companies to design the highest-quality product for the least amount of money, and performing thickness and color tests are effective ways to test quality inexpensively.

“Thickness testing equipment can save powder coaters 10 to 30% on their annual powder consumption because thickness gauges cut down rework,” says Joseph Walker, vice president of Elcometer (Rochester Hills, MI).

This equipment performs precise, accurate measurements of film thickness and color quality to help businesses efficiently coat their products and meet customers’ specifications.

Thickness control

Customer demand for testing equipment has remained strong in the coatings industry.

“Since the economy started to slow down, our sales representatives’ phones have been ringing off the hook,” Walker says.

Thickness testing devices measure film thickness to ensure that the company is not using too much or too little coating for the product. Aside from wasting material and money, applying coating too thick can cause cracking, chipping and discoloration. Ultimately, if the coating cracks or chips, it can become contaminated by dirt and other pollution that can get under the coating. On the other hand, if the coating is too thin, the paint will wear easily and allow corrosion.

Technology advancements have been the key to the growing availability of thickness testing equipment. These improvements have helped manufacturers produce devices that are smaller and more portable, rugged and simple to use. Thickness gauges have also dropped in price because the materials used to produce them are more abundant. The same materials are mass produced for use in cell phones, palm pilots and computers.

“The gauges have become more powerful tools with technology that records data, stores multiple readings and sets the gauge to measure a number of different areas on one part,” Fusco says. “Data can be downloaded from an infrared port with a wireless remote into a PC, organized into a spreadsheet and sent to a wireless printer through an infrared signal.”

Thickness for large quantities

Wagner Systems (Carol Stream, IL) designed the Laser Thermoscope for companies that coat large quantities of products and use a large amount of powder—one million pounds of powder or more per year. The Laser Thermoscope is a closed-loop system that uses a laser to read the mil thickness of powder in its dry state and relays that information back to the controller. The controller then automatically determines if the thickness is within specification. If the powder is too thick or too thin, the machine instantly begins adjusting the powder flow 0.1 cubic meter at a time until the thickness is within spec.

“If a company is spraying one million pounds of powder per year and applying twice as much as it should be, its cost is twice as much,” says Tom Matthey, vice president of marketing at Wagner Systems. “That’s why it is critical to control mil thickness quickly. The Laser Thermoscope is at the exit end of the booth, so the amount of powder being deposited can be adjusted very quickly before the products are cured on the line for 45 minutes to one hour.”

Wagner added a touch screen to the controls to make the third generation of the Laser Thermoscope more user friendly. Appliance, shelving and other flat-stock manufacturers have had the best results with this machine because flat stock has a higher transfer efficiency than curved products, such as tubes, according to Matthey. The Laser Thermoscope also measures the product in nine different areas to ensure consistency.

“Powder savings are the biggest benefit of this machine,” Matthey says. “But it’s not for everyone; it is for large powder users. We have had reports of companies saving $12,000 or more a month in powder. The machine can pay for itself in a matter of months.”

Noncontact thickness measurements

Measuring thickness before the coating is cured to determine the amount of overflow can provide precise measurements. “When powder goes into an oven, the powder melts and becomes similar to a liquid paint, and it flows over,” Walker says. “It is difficult to tell to what thickness powder will melt because it is still in powder form before it is cured.”

Elcometer developed the Elcometer 550 Non-Contact Uncured Powder Thickness gauge to predict how thick the powder will be when it’s cured. This gauge uses an ultrasonic measuring technique that uses sound waves to measure thickness.

“Ultrasonic measurement is difficult because sound is diffused through air,” Walker says. “But, we figured out a way to concentrate that sonic beam so customers can predict the cure-out of the powder.”

Although technological advancements like noncontact systems continue to make thickness-testing equipment more sophisticated, the device is still simple to use. “An average person in a production environment must be able to effectively use the tool without obtaining an advanced degree in physics,” Walker says. “For example, the person who operates the Elcometer 550 on the production line only has to push one button to get a measurement even though the equipment is very sophisticated. The user’s input into the physical measurement of a product should be kept to a bare minimum.”

Nonmetallic substrates

Technology for measuring thickness on a nonmetallic substrate is still relatively new, and companies continue working to find an effective way to determine thickness on fiberglass, wood, concrete and plastic. Paul N. Gardner Co. designed the PosiTector 100 to measure single- or multiple-layer coating thickness on various substrates.

“A nonmetallic-substrate thickness gauge uses ultrasonic technology that pushes sound through the paint so that it echoes off the substrate,” Fusco says.

This technology can take one reading and determine how thick each layer of the coating is for as many as five individual layers. The gauge can be used on plastic, wood and concrete. Because there are numerous uses for the PosiTector 100, the instrument can be used on-site, on a factory floor or in a lab environment.

Other companies are also investing research and development efforts into measuring thickness on nonmetallic substrates, particularly on plastic. “Measuring thickness on plastic is really difficult because the physical properties of plastics and paints are virtually identical,” Walker says. “Oftentimes, people end up running test panels with aluminum strips over them, and then they paint over the strips and use an aluminum gauge to measure thickness.”

Color control

Thickness testing is also important because coatings that are too thick or too thin can often lead to color mistakes. For example, if the primer is too thick, it will crack, and the cracks could affect the shade and brightness of the color coat. Thus, color testing has become a standard quality control test along the same lines as thickness testing. Although color equipment used to be complicated and expensive, technology has pushed the price of color instruments down.

“In the past five to 10 years, we have seen an expansion of the number of companies investing in color-testing instruments,” says Jim DeGroff, president of ColorTec (Clinton, NJ). “Anyone who manufactures and assembles painted parts needs color-testing equipment. Right now, we’re in a more competitive world because of the economy. So, the company with the best quality at a competitive price is going to win.”

Color is often considered an indication of quality, so it is imperative that color is consistent and aesthetically pleasing. “If the color doesn’t match, the coater needs to change the formulation, and he’ll have to either respray or repaint the part,” Fusco says. “That can get expensive quickly. Testing color consistency and monitoring activity prior to coating the part can save a lot money.”

In most cases, companies invest in color equipment because their customers require very specific colors or have complaints about inconsistent color, which can mean lost business. Color instruments provide manufacturers with a numeric measurement that they can compare to their customers’ set color specifications.

“An instrument provides a number to evaluate,” DeGroff says. “A buyer could say, ‘This color isn’t good,’ and the seller could say, ‘Of course it is.’ This debate could turn into an argument if there is no objective evidence. The numbers derived from a color instrument can act like a referee or at least as a starting point for discussion.”

The equipment creates a database of the coaters’ color expectations, color that is actually being produced by the manufacturer and color that is delivered on a finished product after curing. Data can be saved to constantly monitor the quality of production.

Rugged equipment

ColorTec designed its spectrophotometers to measure more quickly and precisely. Light emitting diodes (LED) are the light source for ColorTec’s color-measurement instruments. Originally, LED instruments were used as colorimeters, which are straight color-measurement instruments.

“Spectrophotometers provide more data and perform a more precise sampling in the visual spectrum than colorimeters,” DeGroff says.

Along with expanding the technology of color-testing equipment, ColorTec’s LED line was designed to perform in a rugged environment. “Customers want a rugged, easy-to-use instrument,” DeGroff says. “If you can’t drop it on the floor without worrying about it breaking, it really isn’t suitable for a plant environment.”

ColorTec’s LED instruments incorporate an optical device the size of a dime and are designed to be stand-alone, battery-operated devices. When an instrument is connected to a PC, it can gather data in the field, save the measurement and download the data. The on-board computer logic was designed to make accurate measurements, tag or mark measurements for further identification or get a pass/fail color test instantly. The LED instruments hold as many as 500 measurements and come with an RS232 interface, and all of the data can be printed out from a PC.

Into the field

The increasing availability of lightweight, portable equipment has been another change in color technology. Companies are more apt to buy color instrumentation if it is portable and easy-to-use.

“The instrumentation today is small enough that it can be taken into the field pretty easily,” Fusco says. “You can measure products on an assembly line, and if a customer has a problem with his parts, the instrument can be taken to the customer’s site.”

One portable instrument on the market now is the Spectro-Color gauge by Paul N. Gardner Co. This instrument was designed to produce repeatable measurements for measuring liquids, solids, pastes and powders.

This instrument is also designed to maintain accuracy, even in the most rugged environments. The gauge has a plastic housing feature that protects the precision lens system from dusty environments. In the past, color equipment required clean rooms for the sensitive optics; equipment now is designed to be more versatile.

Dark colors

Light colors reflect light easily, which makes measuring them easier than measuring blacks. Thus, equipment to measure blacks must be extremely sensitive to pick up the slight reflection from black. HunterLab (Reston, VA) developed a low-cost, high-tech instrument called the ColorQuest XE, which can perform many of the functions of HunterLab’s top-end product and has a high sensitivity to measuring carbon black.

“It is tough to measure carbon black because there is hardly any light coming off the color,” says Hal Good, director of marketing services. “You are trying to measure the light on black, and blacks do have some reflection because there is no perfect black.”

If an absolute black were to be measured, the black would absorb all of the light.

“An instrument that is used to measure blacks must have a high sensitivity and a very low noise level so that it can detect any amount of light that is reflected,” Good says.

Economics

Thickness and color testing have grown more important in today’s coatings industry because of the necessity of stricter quality control testing and the growth of sophisticated technology. As the economy slows down, companies are increasingly forced to produce higher quality product at a competitive price to stay in business. Thickness and color testing are useful ways to save money and increase quality.

“When the economy was stronger, companies were concerned with getting the product out the door and didn’t care as much about film thickness,” Matthey says. “Now, there is less pressure to get products out the door because demand isn’t as great, and people have to watch their costs.”