Your take on rust converter paint

[Ralph Bauer]

Thinking about removing the large, coarse rust with a wirebrush, maybe drill wire brushes but not sand an old combine down to the shiny metal, because the metal is already pretty thin. Seen so called rust converter/primer that (chemically?) convert rust in a useable primer like coat which one can then paint with a topcoat. Not looking for restauration quality, but rather to preserve the old pull behind combine which I plan on using in beans, maybe a little barley, wheat. Would leave it as is, but more than 80% is rust, thinning the metal. Will shed her when not in use.
Thoughts, ideas, feedback? Thanks in advance! Ralph.

 

[36 Coupe]

Rust converters are usually latex based so they will freeze.I dont use them when freezing weather starts.I did a lot of work on my pickup truck chassis.Road salt had done a lot of damage.I used my angle grinder with a cup brush to knock off the loose rust.Used all the rust converter I had on hand and put on a coat of zinc oxide primer.Been painting farm equipment for 60 years and find zinc oxide primer holds up best.Aluminum paint makes good primer on rust metal.Holes in sheet metal are best patched with fiberglass cloth and boat resin.Marine suppliers have the best prices.You can finish up with bondo for a pretty surface.I use oil base paint from the farm store for finish coats.A 4 inch angle grinder with a cup wire brush will do better than drill wire brushes.These brushes do shed wire so I use a full face mask or goggles.My angle grinder sharpens sickles, grinds rivets,cuts light metal.I have an old Black & Decker that has done a lot of work.Dont go for the cheap ones, they wont stand up.The spark stream will mark glass.

 

[showcrop]

You may be asking a little too much of rust converter, if I understand you to be saying that you are looking to remove only the large loose pieces of rust and convert most of the rust into something solid. I used to use the latex stuff that 36 coupe refers to but found that rust would still extend under it. I have had sheet metal with some rust pits on it professionally prepped and painted only to have rust bubbling up through it 3-6 years later where the pits had been. Rust converter will convert only the rust that it can contact and it can penetrate only so much. If you want it to last any amount of time you need to clean it up shiny as 36 coupe says then use phosphoric acid wash to convert the rust in the tiny pits and scratches. Then prime with epoxy primer.

 

[Rod (NH)]

Take a look at <a href="http://www.por15.com/POR-15/productinfo/1GB/">POR 15</a>. It's a moisture-cured urethane so you certainly don't want to spray it without a supplied-air respirator but it brushes extremely well. Not cheap though.