Spraying rust converter

[Charlie M]

This isn't about a tractor but painting an old locomotive is the same process. We are going to do a cosmetic restoration of an old steam engine at the rail road museum where I volunteer. We are going to pay to have it sand blasted but my thought on putting on a finish is to hit it first with a rust converter. Is there any problem if the material is sprayed on instead of brushed or rolled or any other technique? At home I brush it on but that is for something small like a wheel and this locomotive has a lot of area to cover, including some unusually surfaces. Anybody got an idea how much coverage you can get from a gallon. I'm thinking something like this locomotive will use 2-3 gallons. Its a small shop size locomotive.

 

[RedGreenGuy]

This isn't about a tractor but painting an old locomotive is the same process. We are going to do a cosmetic restoration of an old steam engine at the rail road museum where I volunteer. We are going to pay to have it sand blasted but my thought on putting on a finish is to hit it first with a rust converter. Is there any problem if the material is sprayed on instead of brushed or rolled or any other technique? At home I brush it on but that is for something small like a wheel and this locomotive has a lot of area to cover, including some unusually surfaces. Anybody got an idea how much coverage you can get from a gallon. I'm thinking something like this locomotive will use 2-3 gallons. Its a small shop size locomotive.

I spritz spray Eastwoods "After Blast." But always wipe it down afterwards because its thine and runs. Lots of wiping on a locomotive.

 

[sms]

I think most I know of are spayable. Check manufacturers recommendations.

 

[used red MN]

What degree of sand blast are you planning on, white(bare) metal? If so rust converter may not be the best coating to follow up that prep. From a rust converter website. “Good surface preparation will enable the Rust Converter to work effectively… The object of this step is to get any loose or flaking rust off as it does not provide a stable surface. The point is not to remove all the rust (this defeats the purpose of Rust Converter) as Rust Converter chemically bonds to the rust and seals it in.”
That is from a website I will link. I don’t know anything about their products. It just came up in a search when I was looking for better wording for the info above. I would probably suggest a quality primer. You might try asking this down in the “Paint and Body Work” forum and see if another recommendation comes up.
The rust store website

 

[Timmycornpicker]

This isn't about a tractor but painting an old locomotive is the same process. We are going to do a cosmetic restoration of an old steam engine at the rail road museum where I volunteer. We are going to pay to have it sand blasted but my thought on putting on a finish is to hit it first with a rust converter. Is there any problem if the material is sprayed on instead of brushed or rolled or any other technique? At home I brush it on but that is for something small like a wheel and this locomotive has a lot of area to cover, including some unusually surfaces. Anybody got an idea how much coverage you can get from a gallon. I'm thinking something like this locomotive will use 2-3 gallons. Its a small shop size locomotive.

Don't apply rust converter on clean, shiny metal after sandblasting. It won't do anything. What I would do is look for areas of deeper rust after blasting and spot treat those areas. Then prime and paint. As far as application goes, I've sprayed it on but noticed that I sometimes have to come back for an additional treatment vs. a one-and-done brush application.

 

[Janicholson]

Don't apply rust converter on clean, shiny metal after sandblasting. It won't do anything. What I would do is look for areas of deeper rust after blasting and spot treat those areas. Then prime and paint. As far as application goes, I've sprayed it on but noticed that I sometimes have to come back for an additional treatment vs. a one-and-done brush application.

I agree. The chemistry is intended to bind rust, not bare metal. Prime and exterior grade epoxy, or automotive enamel is best. Make sure the primer is compatible with the paint. Though it can be applied to blasted material, it may not be stable without rust to convert. Jim

 

[Charlie M]

I've got the contractor coming tomorrow to give me a quote for sand blasting and will know more after that. At the moment I'm planning a budget for the board and will include rust converter even if later we don't go that route. I'd be surprised if they get an 80 old piece of machinery down to shiny metal but we will find out.

 

[Timmycornpicker]

I've got the contractor coming tomorrow to give me a quote for sand blasting and will know more after that. At the moment I'm planning a budget for the board and will include rust converter even if later we don't go that route. I'd be surprised if they get an 80 old piece of machinery down to shiny metal but we will find out.

The local tourist line contracted an ex-CNJ commuter coach to be sandblasted once. Shot a lot of holes in the sides that had to be cut out and repaired. But they were expecting that on a 90-year old passenger car.

 

[Oregon Tractor Jack]

I just put Ospho converter in a regular spray bottle. It will pretty well trash the sprayer after a couple of weeks. The acid eats the o-rings. As mentioned you have to wipe and rinse after the rust has turned black. If you don't there is a white powder left on the surfaces and paint will not stick to it.

OTJ

 

[Charlie M]

Maybe I should ask this question - what's you're thoughts on rust converter chemicals vs primer labeled for rusty metal. Is that a better way to go after sand blasting?

 

[Janicholson]

Maybe I should ask this question - what's you're thoughts on rust converter chemicals vs primer labeled for rusty metal. Is that a better way to go after sand blasting?

Rust needs to be dealt with either by light sanding/wire brush to remove scale and loose flakes, or cleaned to bare metal/sand blasted. Once cleaned up the still rusty stuff must be converted, while the bare metal must be primed. Painting on converter covering light tight rust only then priming with overlap onto that is OK. Jim

 

[Ray,IN]

I spritz spray Eastwoods "After Blast." But always wipe it down afterwards because its thine and runs. Lots of wiping on a locomotive.

I agree with RedGreenGuy. After sandblasting don't waste time getting it coated, surface rust sets in very quickly.

 

[Tgrasher]

There's really no good way to paint rusty metal but rust converters do work where all rust can not be removed. Following with red oxide primer coats, the metal is sealed better against further rust. Even clean cast metal needs red oxide primer for a good base.

 

[da.bees]

I have more concern about possible health than whether spray works as well as brush. I've been pleased with Rust oleum rusty metal primer following sand blast. If an item is rusty at the onset, you will likly have flash rust between blasting and priming so converter or rust treatment primer should be used. I wouldn't apply lacquer or 2-part paint over Rust oleum. To prevent flash rust some auto body paint systems call for quick wipe with weak solution of converter on spots where metal is exposed during sanding.

 

[showcrop]

I have been using a lot of rust converter for probably over thirty years. Some worked well, others, that were supposed to be single step, not so well. One that worked very well was RustMort by SEM. Brush on; brush some more: rinse off. Then I discovered that phosphoric acid works every bit as well. a little goes a long way. and spraying it on works very well, but it is best to to agitate it with a brush where ever there are pits, even after blasting them. As Timmycornpicker posted you can get white residue if you spray it on bare clean metal. To avoid that I put small parts in a five gallon bucket of hot water for a few minutes, They will air dry just fine with little to no flash rust after. Large panels, after agitating the pitted areas with the brush, I pressure wash with hot water to flush off any excess. I have also found that flash rust after the water spray can be avoided by wiping with a cloth soaked in alcohol. I had a situation where I tried a primer for rusty metal to seal against rust, but after two years rust in a few pits bubbled up the paint from underneath. A friend had a lot of pits two years after treating an MG Midget with a one step rust converter. You can't short cut. You need to have the surface warm. It is perfectly OK to spray it on. A quart goes a long way. I used less than a quart on my very rusty Datsun roadster in 2015-2016, and nary a single rust bubble yet. You need to agitate it in any area where there are pits, then spray the excess off aggressively with hot water. I recommend a quick wipe with alcohol in completely rust free areas. The phosphoric acid is available in gallons at restaurant supply stores as limescale remover, and at dairy supply stores as milk stone remover. I would avoid using much pressure when spraying and wear a mask in case you get fine droplets.