While a bit expensive, a POR-15 paint job will last close to forever
www.por15.comYou will need the
- Metal Ready (phosphate surface etch)
- POR15 base coat (Clear is the best for moisture resistance)
- Self etch primer in a spray can (to let the black top-coat bond permenantly to the clear base-coat)
- Two-Part "Hardnose" top coat (in Black)
Clean barrel with lots of soap and water, followed by 70%-100% Isopropyl Alcohol. Let barrel dry completely before proceeding. You are removing dirt, grease, oil. Don't panic about a bit of thin surface rust. In fact, surface rust gives the POR15 something to stick to and they actually recommend letting freshly abraided surfaces sit a few days after degreasing to "age" a bit.
Brush it on, don't spray it on (unless you have proper breathing equipment - requirements are on the web site. Without it, the spray will cure when it contacts the moisture in your lungs and can kill you). They didn't have paint sprayers untill the early 1930's or so, so any paint job done on a BP cannon would have been brushed anyway. The POR15 flows nicely, so brush marks will not be a problem..
Use 3 very thin coats of both POR15 and also the Hardnose. Do it on a dry day. The POR15 is moisture cured, so thick coats combined with humid days can cause rapid cure reactions and form bubbles. If it bubbles a bit here and there, you can sand the bubbles down (with some effort) and apply the next coat.
Don't use a plastic cup to hold the mixed Hardnose (or the POR15 for that matter) as it will eat thru the bottom of the plastic cup in about 5 minutes (been there, done that). A clean metal can is better choice.
This stuff is amazing. If you paint something with it, the paint is going to be there for a long, long time. That includes your own skin by the way (once again... been there, done that).
Rick