Panel Preparation

Ask an Expert From: Products Finishing, ,

Posted on: 2/1/2005

Question: Your answer to P.R. in the January, 2005 Painting Clinic, regarding panel preparation seems, at least to me, incomplete.

Question:

Your answer to P.R. in the January, 2005 Painting Clinic, regarding panel preparation seems, at least to me, incomplete. PR asked how various members “can be on the same page” regarding surface preparation. You answered that the panels must be primed without suggesting a primer. Do any of the members have spray equipment? Perhaps they can use a primer from a spray can. First, I would suggest that one person primes all of the panels so that they are relatively uniform as far as film build. Varying film thicknesses may affect the gloss of the finish coat. Film thickness could also affect the color as it appears to the eye.

You mention that the steel panels should be primed. I agree as far as corrosion is concerned but, my experience is that adhesion to clean steel is far better than adhesion to aluminum—unprimed aluminum.

When I read your phrase “Don’t try this at home kids” I was really surprised that you said that they could proceed with various members finishing panels at home. I can only see problems and hazards if this is done by inexperienced persons at home. Perhaps your answer should have been as follows:

1. Clean steel and aluminum panels thoroughly with a paint solvent, such as mineral spirits.
2. Spray paint the steel and aluminum panels with a zinc primer. There are primers in spray cans that can be used. It is suggested that one person do the priming so as to have uniformity.
3. Apply the color coat to one side of the panels to a dry film thickness of 1.5 mils.

Again it is suggested that one person apply the colors to ensure some uniformity in application. Do not try to force dry these panels in an oven at home.

I just can’t see various persons doing a good job. I also can’t see how various persons can achieve a uniform wet film thickness. One person can get the “feel” of the spraying and correct his mistakes as he goes along.

Of course proper ventilation is required. Any source of combustion should not be near where the coating is applied. I am assuming that solvent type materials will be used. Waterborne materials can be used if the colors and glosses lend themselves to this type of material. S. B.

Answer:

Thank you for writing, S.B. I recognize your concern, since we were both in the “painting business.” Everything you say is true. In our former industrial lives, your recommendations would be perfect. The key statement in the January, 2005 Painting Clinic was, “...since most people don’t have access to industrial and laboratory painting equipment...” The question as published didn’t go into details about the painting skills of the committee members. However, P. R. assured me they are all accomplished modelers. He further stated they are all familiar with paints and painting. Some of them do custom painting of model railroading equipment. Although I agree with you and share you concerns, panel preparation by one person, would be impossible because of time and cost constraints. Although most of the committee members involved are located East of the Mississippi, the cost of transshipping test panels would be prohibitive for a volunteer organization.

When I had a real job, I would have had P. R. send all the wet samples to me. As a public service, I would have primed the panels and applied the various topcoats at the Westinghouse Research Labs (on my lunch hour of course). Unfortunately, my paint lab and the Research Labs with all its equipment has evaporated.

 



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