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Q&As since 1989
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Painting marine compasses and boat/ship bronze & brass
MARINE COMPASSES
All About Marine Compasses and Their Adjustment
by A. Pickles (1990)
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Finding the Error of the Marine Compass on Board Ship
by Benjamin Franklin Greene (1875 -- in public domain)
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The Marine Compass: (paper presented to United States Naval Institute at Annapolis
by Benjamin Franklin Greene (1874)
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Q. I do marine compass repair. Many marine compasses have a bronze "top ring" which seals the oil chamber. Frequently the top rings are tarnished or chipped --> they need repainting with a gloss black enamel. I've had much trouble getting a paint/primer to bond tightly to the bronze.
Things tried:
1) Krylon with and without primer
2) Hardhat with and without primer
3) Etching the clean bronze with ferric chloride
4) High % zinc primer
In all cases the problem occurs in the countersunk screw holes when the SS mach screws are torqued to proper ft-lbs. The paint tears away from the holes and surrounding surface. Much frustration! Here's hoping for some wisdom.
Note: I am NOT painting a bronze color - rather I need to paint black ONTO bronze.
Thanks in advance.
Robert S.Petersoncompass repair - Elgin, Illinois
2004
Brass Black Metal Finish
on
eBay
or
Amazon
(affil links)
A. Try an oxide solution. Birchwood Casey Company has a Black gel that you paint on with a brush [Brass Black on eBay or Amazon] . It turns the compass black with a process such as gun bluing. You need to rough the surface up a bit with a sand blaster or sandpaper to allow the oxide to bite.
Rich Darby- Danville, Illinois
2005
A. I also repair compasses. That material is usually not bronze but naval brass (High zinc content). We continue to use Krylon with a primer. The key seems to be curing time. We do not get the problem if we allow a 24-hour cure before inserting fasteners. I have also used a dab of petrolatum in the holes on some jobs.
Bill Haimes- Everett, Washington
July 16, 2009
Q. I'm not a professional finisher, but I do have a big boat with lots of bronze and I hate verdigris so it's a curse.
When polished I want bronze to stay polished and when painted I want it to stay painted - neither of which is easy.
First thing, nothing will stick to bronze tarnish - it has to be removed and I think preferably to at least a low polish state.
I don't believe any primers (etch or otherwise) will help, your finish coating has to go directly onto the metal.
For a black coating to handle mechanical stress, I think your choices boil down to: epoxy paint, powder coating, or electroplating with black chrome.
For a clear finish "Wattyl Paints" supply an aerosol spray specifically for copper that works on Bronze - (5 years in full sun before it starts to tarnish under the coating) - being a very hard coating, it may work as a primer under black paint - But I'd still use epoxy.
Thought of polishing the Bronze ring? very nautical look and the tarnishing problem will be tomorrow's problem for somebody else.
good luck
- Brisbane Australia
June 7, 2009
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