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Powder Coat and Commercial Paint Specifications on Drawings

2007

We have a bit of a documentation issue with paint and powder coat specifications.
We make industrial conveyor belt ovens.
The parts for these ovens can be made by several different suppliers and paint or powder coated with several different types of paint or powder coat.
How can we generically specify the paint or powder coat to be used so that it will not matter what vendor we purchase the panels from?
We currently specify the paint spec for each type of paint or powder coat that each different supplier uses. This causes some documentation problems if a new vendor with a different type of paint or powder coat is used. this could mean updating many drawings just for a new vendor.
How can we make a broad or general requirement for paint.
Color should match and properties should be comparable.
How is this typically done?
Any suggestions?

Thanks for your help!

Nick Harkeem
mfg eng - Billerica, Massachusetts

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The purpose of a spec is to tell people what they must do, not to cover what they did, Nick. You seem to want to use your spec more like an ingredients list on a box of cereal than as instruction on what the vendor must do. It's fine to leave flexibility, but you need to pick a small number of alternatives and the vendor must comply with one of them. If you don't have particular known needs, your vendors probably have specifications which they would be happy to give you to "write themselves in". Take one or two of those and strike out the words that seem too proprietary. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

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2007

Thank you this is exactly what I was getting at.
But what properties are generally specified for paint and powder coat. Like I said the main thing is the color and gloss. There seems to be all kinds of ways to specify the color. The gloss appears to be standard for the specs I've seen by specifying a number of units on a 60 degree gloss meter. But the color can be very vague. I've seen some standards like RAL but it seems that there are more non-standard colors. Is there a way to find the closest standard color to our paint chips? Then we can reference this standard color on our drawing. But which standard or standards are more universal in the paint and powder coat industry? This is where we have no expertise and some of the paint suppliers I've called have not been much help.

Nick Harkeem
BTU - Billerica, Massachusetts

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Dear Nick,
I think that you have already grasped the need to be the driver and not the driven. You appear to have some knowledge of gloss and the problems of specifying colour. To start, you must decide that liquid paint is going to be a no, no. Therefore, we are going all powder, yes! What gloss level - it should not be too matt or too glossy -- I would suggest a nice compromise would be 70-75% gloss @ 60°. Colour, experience shows us that purchasing any specific colour from several different sources can lead to problems. A guaranteed way of a perfect colour match from all your PC applicators is to free issue them with powder, i.e. you purchase a quantity of powder to your specification (resin type, gloss, colour etc) -- I would suggest a Polyester powder because it has good heat resistance. Your specification should inform the coater that the powder must be cured for 10-12 minutes at 200° C metal temp. Testing the powder finish should include, colour (has it turned yellow due to over baking?), cross hatch (adhesion), gloss (over/under bake). I do not think you need to go any further than these tests -- do not forget that you must test the items against your spec on delivery of coated items from your supplier to make sure all is well.

Terry Hickling
Birmingham, United Kingdom
2007