Help me choose my paint

Question:

I have a 1979 and a 1980 MGB that I am restoring and would like to know what type of paint is best for the repainting job. What gives the best result and what is the difference between types of paint? Also, what types of paint came on these cars from the factory back in 1979 and 1980?

Answer:

Your MGs originally were painted with acrylic enamel. To answer your question about types of paint, basically lacquer paint dries, but it does not cure. Curing is a chemical process that happens within the paint. Lacquer off-gasses and dries very hard, but it is more prone to shattering if hit by a rock or bit of debris. Enamel cures and changes in the process, and that takes a bit of time, but it is softer and more flexible than lacquer.

Acrylic is a plastic that is used to make paints more durable. Nevertheless, because it just dries, lacquer will literally melt and wash off with a lacquer-thinner-soaked rag. Enamel is somewhat vulnerable to such treatment as well unless it is molecularly cross-linked using a hardener. But both of these technologies are to a great extent obsolete today.

A base coat-clear coat two-step system is generally used these days, and in some states such as California, the base coat must be waterborne in order to cut down on the VOCs (volatile organic compounds) emitted during the painting process. The color coat is then sprayed with a clear coat that contains isocyanates, which are deadly to breathe. You need to know this if you are contemplating painting your own car using this system. Truth is, these modern systems are best left to pros who wear a complete hazmat-type suit, have an independent air supply and use a properly equipped spray booth.

One other factor to consider is that unless you strip the car to bare metal, your new paint job will only be as good as what is under it. And paint that is too thick will crack due to temperature changes. Paint often gets too thick in valleys and recesses, and is usually thinnest on the tops of fenders and hoods. If you can afford it, I would strip the car to bare metal and remove any trim and rubber gaskets and have it painted professionally. The seals most likely need replacing at this point anyway.

This 1961 Bentley has a coolant leak so small that you can’t see it but you can smell the antifreeze.