Acid Etch Primer and Threads

[Ray Massa]

As a new builder just starting on an M26, I have been painting with UPOL primer, great stuff. Just wondering if I should mask off internal threads on aluminum pieces. I do mask external threads. Asking because I am thinking that when the screw does into the thread they will be dissimilar metals and don't want a corroding problem.

Thanks.

[Robert E Morey]

Ray for threads, its more an issue of paint/primer build up on threads making them more difficult to assemble. I mask both internal and external threads just to keep paint out. It would be nice if both surfaces could be painted, but then they are way more difficult to thread together.

Dissimilar metals is not ideal - but that's how the kits are made (steel axle - aluminum arms). I give both a good coat of primer and paint once assembled together, which slows moisture intrusion and hence corrosion. If you run em through water and the steel parts get wet - eventually the threads will rust - no way around it.
Hope that helps,
Bob

[Ray Massa]

Thank you Bob. Makes sense. I figured as much but thought I was overthinking this.
Much appreciated.

[Jerry Carducci]

Just a note regarding metal to metal interfaces. I've been aware and concerned about galvanic corrosion for quite some time
although except in conditions not normally found in or around our models this sort of corrosion has been rare to non existent.
Being in the SF bay area we're never that far away from the ocean and effects of it. I've seen what salt spray and moisture can do. Aluminum and brass together out in this environment and unprotected is not long for this world.

That said some of my larger models are 45+ years old and I've never seen corrosion between different metals in any of them and they are goodly mises
of cast and rolled aluminum, steel, brass and copper. Since I came to the hobby by way of ICE powered models which are inherently more messy I never painted the inside of my models and never screw threads. Now it's true I don't keep my models in humid conditions if I can help it but they're no strangers to mud or water.

I'll never say don't use good primer but threaded components I don't generally paint.

Jerry

[Ray Massa]

Thanks for the comments Jerry. As I mentioned in my original posting, maybe I am overthinking this, and overly worrying about this. But that is based mostly on what I have read on the forum and seemed to be of a concern to some. I probably would not have thought about it much otherwise to the extent I have been. I have been masking threads in all cases as Bob has mentioned doing. I am good with that and will not worry about it any longer! Thanks again for taking the time to reply.

-Ray