Paint or Not to Paint!

[BLB27]

Should the inside perimeter around the quarter and rear windows be painted on my 1927 coupe? The locations are shown in the attached photos.

Use a prime coat or a prime and top coat?

[Jerry VanOoteghem]

You'll never regret painting it, even if unnecessary. But, if there's the slightest chance those surfaces may be visible after it's all done, you'll kick yourself for not painting them when you had the chance. Plus, the paint will seal them from the weather and possibly prevent future rusting.

I would also paint the interior wood and metal surfaces with Rust-o-leum flat black to seal & protect as well.

[Joe Bell]

I would paint any thing and every thing that way you seal the wood and metals from water.

[BLB27]

Joe, Thanks. I will do it! Photos will come.

[TXGOAT2]

If at all possible, place the car in a warm, closed space with a dehumidifier for several days prior to painting. Go over the car and tighten joints in the woodwork when the car is good and dry. Then do the painting/sealing, making every effort to completely seal wood parts, paying careful attention to end grain and joints.

[BLB27]

When I am using Rust-Oleum prime on the metal, I also use it on the wood adjacent to the metal. Should I use a wood paint on the wood?

[TXGOAT2]

I'm not sure about the wood/metal paint question. I do know that anywhere where steel is in contact with wood will be a focus of decay if water is present. I would make a special effort to get paint or sealant to seep into areas and joints where wood and metal meet, and where screws or nails or tacks are used in wood. Thinning the paint would be helpful.

[Wayne Sheldon]

Regardless of how it was done originally? Remember, originally the cars were built with an expectation that they would remain viable transportation for a decade or maybe two at the absolute outside. Average life expectancy for a model T in the model T days was less than seven years. Today? We would like to think our surviving model Ts and other antique automobiles once restored should stick around for another century (it might be a foolish expectation, but still?).
For that reason, anywhere wood and metal meet should be very well sealed to prevent future corrosion caused by moisture in the wood. As much as is reasonably possible, very thin enamel should be flowed in between wood and steel that are already attached. Tipping the body to aid the flowing of paint can help.

Arguably, areas of wood not against steel might should not be sealed and/or painted. Paints and most sealants have a bad habit of splitting and pealing over the years. And humidity moisture has a nasty habit of finding its way in in spite of wood having been sealed. So unless you have a fool-proof product? Often, it is better to leave areas not against the steel left open which allows humidity moisture to evaporate out during dry seasons.
Yes, that is a heavily disputed opinion. But I spent thirty years chasing water ingress in communication systems cables and wires. If you cannot seal it one hundred percent!? Water WILL find its way in, and then the sealant keeps it in!

[TXGOAT2]

A thin coat of a sealant that would remain flexible would be the ideal for wood. As mentioned, paint or other coating that cracks or peels will allow moisture in, and then the remaing coating will tend to keep moisture in the wood. A penetrating sealant, like thinned down paint, is best. I don't know why contact with steel promotes wood rot, but it does. Sealing the wood prevents it.