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Q: I am currently refurbishing a bronze plaque in an outdoor setting. I used a vinegar, salt, and flour paste mixture to remove the corrosion. I have satined the highlights and would like to protect the plaque from the weather until I can lacquer it in the spring. We are located in upstate New York, so the winter weather can be severe, it is already to cold for the lacquer.

It sounds as if you simply want to apply a temporary protective coating to the plaque until the weather changes. If so, you might want to go to the Tectyl website  and select a temporary protective that will get you through Veterans Day and into the Spring. The Tectyl products are both solvent based and waterborne. Some are thick, greasy coatings, others form a solid thin film. Some must be removed with solvents, others can be removed with hot water. Some are colored, while others are clear.

I suggest you call someone in their tech service department who can immediately select a product suitable for your application.

When the weather turns and you are ready to apply the permanent coating, you will first need to remove the temporary protective and then apply your lacquer.

Date asked: 02 November 2009

Q: We are experiencing primer and paint adhesion problems from our supply base on parts that receive an aerospace anodized coating and either a primer or enamel topcoat. We are having trouble determining if the adhesion failures are caused from a faulty anodize coating or if it is a primer/topcoat issue. Is there any way to determine which factor is causing the failures? Any advice would be greatly appreciated.

This problem probably requires you to have the adhesion between the organic coatings and the anodized aluminum evaluated in a laboratory.

One method I suggest is to apply the primer and/or topcoat to some standard conversion coated Q-panels and evaluate the adhesion. If adhesion is good, your adhesion problem is likely not caused by the primer and/or topcoat.

How do you pretreat the anodized aluminum? Do you apply a conversion coating to the substrate, or is it possible that there are contaminants on the substrate? It is possible that you don't have enough "tooth" on the aluminum to provide adequate adhesion. Is this a new problem, or have you be having it for a long time?

If you have the capability to perform the tests in your own facility, then do so. If not, I do have a lab in which I can perform such tests.

If there is a contaminant on the anodized aluminum, I would be able to analyze it using an electron microscope in conjunction with (energy dispersive X-ray spectroscopy.)

Date asked: 28 October 2009

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