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A few questions about making best use of old powder coating powders

2007

Dear Friend:
I'm grateful if you help me about these questions:
1- What is the explanation for the color change with particle size distribution for a powder coating?
2- What mix is the best of virgin and recovered powder for not changing powder coating?
3- What kind of particle size distribution do you recommend to me for mixing two products of different colors in order to obtain the third color? Example: yellow and green. This question is because we have in stock some colors from a long time ago, and we want to obtain different colors.

Thanks a lot

Margarita Arango R
Reseach and development powder coating - Medellìn, Colombia

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Dear Margarita,

I am not sure if you are a user or mfgr.. However, some users do mix reclaim in proportions of 10-50% - it is what comes out of the oven is the answer, at what proportion is the coated work acceptable. Particle size in a powder varies from small amounts of sub micron to small amounts of particles over 100 microns. Mixing powder of two different colours is unlike liquid paint (white & black = grey) mixing powder results in a speckled effect we tend to call a salt and pepper finish.

Terry Hickling
Birmingham, United Kingdom
2007