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Ask the Expert Question-and-Answer Archive

by Ron Joseph

March, 2005

Making Different Colors of Polyurethane

Q. I am in the midst of painting a sailboat and the color selections I am seeking I cannot find with the various marine paint companies. Can I mix two different color marine poly urethanes together for a top coat that I am looking for? I am looking for a ruby red or wine red, can I attain this color by mixing black with bright red? Thank you for your advice.

A. I don't have a definitive answer for you since I don't know the formulations of the black and red polyurethanes. It is possible that you can mix the two colors, but you will need to do some experimentation first.

Suppose the mixing ratio of the black with the curing agent is 2:1 and the mixing ratio for the red is also 2:1, then first mix the red and black components to give you the desired color, then mix the new mixture in the same ratio 2:1 with the curing agent.

To insure that you have not compromised (lowered the performance of) the coating, apply the new formulation (A) to a substrate similar to what is on your sailboat. Do the same for the red only (B), and for the black only (C). Watch the drying and curing time of A, B and C to confirm that they are all approximately the same. Insure that you achieve the same hardness for all three mixtures. Immerse the coating in water for several days and check their adhesion to the substrate, their hardnesses, etc. If all three mixtures perform essentially the same, then you can be reasonably

sure that (A) will work .. but there are no guarantees.

Good luck,

Best wishes,

Ron Joseph

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