Why Consistent Coating Thickness Is Important

Of the many quality
assurance tools that a coating services supplier should have on hand, coating
thickness gauges are one of the most important for maintaining
high-quality coatings that both perform properly and meet external standards.
Another substantial benefit is cost savings, as keeping coatings consistently within
specifications can reduce material and labor waste. And you should consider
whether the time savings of a tester
that measures continuously at 140 times per minute is worth the investment
to prove your coatings are consistent.

Coating thickness gauges (aka paint meters or mil gauges) are used
to measure dry film thickness without leaving marks on your parts. These are a “non-destructive
testers” with great repeatability in measurements. Dry film thickness is
probably the most critical measurement in the coatings industry because every
coating has thickness range specifications. A coating thickness gauge provides
vital information that can confirm the expected life of the substrate, the
coating properties’ performance, the coating appearance, customer expectations,
and the job’s compliance with international standards.

Managing
Coating Expectations

Many jobs in the Military and Aerospace segments require
verification of the work that you are performing. Suitable coating thickness gauges
are certified by the all the applicable ASTM Standard test methodologies, which
allows you to compete in markets that are sensitive to these specifications. Thickness
testers can also compile the measurements you take and deliver a formal report
that can be shared with the end user.

Most quality shops lay out pass/fail expectations of their customers before
accepting their order, and more end users these days are requiring proof of
testing. Coating thickness gauges demonstrate to your customers that the
coatings were applied to the thickness they requested. This will help you
eliminate rejects and take your customer satisfaction to new levels.

Incorporating thickness measurement into your everyday processes also
saves on material costs. Monitoring coating thickness will drive your coaters
to better control thickness and eliminate excessive wasted coating. As an
example, if you purchase $10,000 in coatings a year and improve your thickness
control by .5 mils, you would save $2,552 a year.

Save Money with Better Technique

By using these simple techniques, you’ll be able to cut out the
waste as well as achieve a better, more consistent finish for your Teflon™
industrial coatings.

1. Plan of Attack: Have a plan before pulling the trigger. Plan to attack trouble
   spots and difficult to reach areas first.
2. Spray
   Distance: The spray distance is based on the spray equipment,
   coating, complexity of the part, and spray environment. By keeping the gun at
   the same distance from the part the entire time you’re spraying, you can
   improve the consistency of the film thickness over the whole part. Increasing
   the gun distance increases the pattern fan size, and the coating thickness
   decreases as it is distributed over a larger area.
3. Gun Angle: Maintain
   controlled gun angle to the part. Yaw and pitch spray angles will result in a
   non-uniform spray pattern distribution, causing inconsistent film thicknesses.
4. Spray Pass
   Overlap: Each spray pass should overlap 50% to 75% of the previous
   pass. Overlapping below 50% results in “striping,” or variations in the film
   thickness. The more you increase the overlap, the thicker the coating, so
   overlapping above 75% requires more spray passes and more coating.
5. Spray Pass
   Speed: Adjust the spray gun speed to achieve consistent films.
   Before pulling the trigger, consider the coating flow rate and the target wet
   film thickness. Adjust the equipment before spraying to find a flow rate that
   lets the applicator move at a controllable, comfortable speed. Spraying too
   fast can lead to decreased film thickness, and sometimes extra coats will be
   needed to make up the deficit.
6. Trigger
   Control: Maintaining a consistent trigger pull on each spray pass directly
   impacts the flow rate, spray pattern size, and transfer efficiency. Start
   triggering immediately before the lead edge of the part and release the trigger
   immediately following the lag edge. Fully pulling the trigger provides constant
   flow rate control. The fluid knob on your spray gun can be adjusted to restrict
   the trigger travel distance so you can always pull the trigger all the way.
   Partial triggering, however, can be very useful for blending and touching up.
7. Edge
   Banding: Partially pull the trigger to spray a light coat around the
   edges of the part. Then spray the center of the part, blending the edges into
   the first coat. Banding can increase transfer efficiency and increase film
   thickness on the edges. This technique ensures the edges get coated completely
   while maintaining consistent film thicknesses.

If you’re looking for more tips on keeping your Teflon™ coating
services at the highest quality consistently, read our other blogs on “Basic Quality
Testing” and “Advanced Quality
Testing.”