Posted by Dennis on Tuesday, November 05, 2002 at 1:58AM :
In Reply to: Re: If I spraypaint over rust... posted by chewie on Tuesday, November 05, 2002 at 0:36AM :
I am not fond of rust converters since they are supposed to change the rust oxide to a primer suitable enough on which to put a new paint job. The problem is that the converter does not always go completely through the rust thereby allowing seepage of air and moisture through the porous black primer that you will see on top of the metal. Oxidation continues on and within a few months you will notice more rust bubbles in the same place. If you live in a dry climate this might not be much of a problem. However, if the converter did not penetrate thoroughly the rusted base could pop off if extreme vibration (think - power wagon offroad) occurs to the vehicle.
I recommend Master Series Rust Sealer. It is a moisture cured urethane filled with finely ground aluminum powder. The powder layers on and fills pits while the urethane prevents breathing of air or moisture through the rust sealer. Top coat it with your choice of primers. This rust sealer literally suspends oxidation.
Make sure that you knock off all of the scale with a wire brush before you paint.
It is similar to POR-15 but I believe it is superior. Foam rubber brush is all you need for application. This is the paint they put on interstate bridges. In that application they sandblast existing rust and spray this paint on.
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