I got a call from one of my customers telling me that on three recent dates he had gotten a particular color of pigmented lacquer from me and that when they were all sprayed out on the same job and put side by side, they didn’t match.

I hopped in the car to go collect samples so that I could get moving on addressing his problem. After all, the project was in the finishing shop now and it needed to get in and out so as not to cause problems for him.

My next step was to mix the one remaining gallon that he gave back to me and spray out a sample on a checkerboard spray-out card. That would give me a sample to put next to his work to compare dry mil thickness and color. I also keep dry samples of all custom colors that we make and attach them to the formula sheet for that color. That way, I have a reference if and when I go back to check my work.

Dry mil thickness and opacity are important in pigmented coatings (paint-grade work). Often the “color coat” is not as opaque as we think it is. The end result will be that the “background” can be seen through the color coat. That will change the color of the finished product and negatively alter the specified color.

The finished door that my client gave me measured 5+ mils in all the places that I tested. His control sample, the one that his client approved, was 1 – 2 mils less. The control sample was whiter in appearance than all the other samples. A completed door that he gave me and my spray-out were yellower. Hmmm…

Let’s cut to the chase. I was now faced with re-matching to the control sample.

The approved sample didn’t match the fan deck paint chip. The reason for that may well be a lack of dry mils on top of the primer. How do I know that? Because of my spray-out on the checkerboard spray-out card. I know how many coats it took to bury the black squares. Please remember that if I can see the black squares, I can also see the white squares. If I can see either, then I will not be looking at a true rendition of the color.

I have a great tool at my disposal that’s really handy. It’s an ultrasonic dry mil thickness measuring device. Take lots of money along if you want to go buy one. They are very expensive but also very useful in cases such as this. I can measure coating thickness and know within 0.1 mil. It takes all the guess work out of these issues. It took more than 3 mils to bury the checkerboard.

None the less, my client’s client had signed off on a control sample that didn’t match the fan deck chip that I originally matched against. I adjusted my formula and shot more gallons for our client. He had to re-spray the whole job.

Until next time…spray on!