OSPHO brand rust "converter".

[JohnEd]

This stuff converts rust to some black kind stuff that is veryhard and doesn't seem to start rusting again very quickly.  Iron phosphate I think was mentioned.  I wire brush the rust or get it sandblasted and then I treat it with Ospho and then I paint it.  Works great and lasts a long long time.  Scratches that rust seem to be impeded in their progress.  Phosphoric acid ain't all that space agr or rocket science but I won't argue with success.  A ship Chandlery introduced it to me.  The fishing fleet boats use it on everything.  It even will prep galvanized so paint will stick.  Aluminum etch....not sure.

Any body have a opinion???

John

[4104GA]

I have used a lot of OSPHO and have found it to really stop rust on steel.  Just paint over it

[johns4104s]

John,

As the UK is just an Island with salt water in the air, fog,rain, sleet and snow. Someone developed a paint on material in diffrent colors called hammerite. You dont wire brush the rust off, you just paint it over the rust. making the rust part of the repair. They sell it here in the US. I used on my 25 years ago on my 4104 were they rust below the bumper.. It looks like a painted it on yesterday.

John

[JohnEd]

thanks John.  I have heard of it but never tried it.  Next time for sure.

John

[bevans6]

It's a phosphoric acid compound, turns rust to a stable compound.  I use it as a spray to treat steel prior to painting with POR-15.  I wash off whatever gets converted.  It can be used to clean aluminium as well, or to prep it for paint.  Coke's active ingredient is also a phosphoric acid compound and it is an excellent rust remover as well, just attracts ants.


Wikipedia:

"Rust removal

Phosphoric acid may be used as a "rust converter", by direct application to rusted iron, steel tools, or surfaces. The phosphoric acid converts reddish-brown iron(III) oxide (rust) to black ferric phosphate, FePO4.

"Rust converter" is sometimes a greenish liquid suitable for dipping (in the same sort of acid bath as is used for pickling metal), but it is more often formulated as a gel, commonly called naval jelly. It is sometimes sold under other names, such as "rust remover" or "rust killer". As a thick gel, it may be applied to sloping, vertical, or even overhead surfaces.

After treatment, the black ferric-phosphate coating can be scrubbed off, leaving a fresh metal surface. Multiple applications of phosphoric acid may be required to remove all rust. The black phosphate coating can also be left in place, where it will provide moderate further corrosion resistance. (Such protection is also provided by the superficially similar Parkerizing and blued electrochemical conversion coating processes.) "

[bryanhes]

bevans6,

If you are using a "rust converter" before applying the POR 15 it may affect the bonding. POR 15 does not recommend it. It is meant to go directly on the rusted or seasoned metal unless you are using the POR 15 Metal Ready product to prep first. POR 15 prefers to adhere to surfaces with "tooth" rather than smooth or glossy surfaces.

I have used it many times in classic car restoration. I would usually just knock off the loose rust with a wire brush and make sure there are no grease or oil on the surface.


Bryan

[FloridaCliff]

John,

I have used it for a long time.

Works great!

I get off the bulk of the loose rust, then spray.

Cliff

[bevans6]

I was led to believe by the Canadian distributor that POR-15 Metal Ready is mostly a phosphoric acid compound.  The MSDS says it is, anyway, regardless of what their marketing material might imply.  In any case, I use the POR-15 Metal Ready as my rust converter.  And to treat new material, just like the instructions say...  I find it works well.  I use the Marine Clean too.  

http://www.por15canada.com/msds/metalready.htm

Brian

[Songman]

I've been using a product called Rust Grip. I've never used the others but I have heard horror stories about POR15. Rust Grip is supposed to be industrial use. I used it on the pan of a VW Bug I am building for my daughter. It was very easy to use. It even changes color to let you know it is right. I have a buddy who is a distributor so can get good deals on it.
http://www.eaglecoatings.net/content/rustgrip.htm

I also used the SuperTherm product that is mention on that link. Industrial strength insulation and vibration dampening. The VW was my first use of either of these. Next I am going to use them on an old Jeep truck I am restoring. Hopefully by then I will have figured out how good it will be for buses.

[Jeremy]

Bodyshops used to use pure phosphoric acid for wiping over metal prior to painting, but I don't think it's possible to buy it nowadays due to safety regulations - however, as has been pointed out, all the various proprietary rust treatments are phosphoric acid-based. The one I use is called 'Krust' and is produced by Hammerite. I love it because it is really thin and it will find it's way down into all the nooks and crannies of a component that your wire brush could never reach. It looks just like milk when you appliy it, and you can really soak the rusty component with it - then by the next day the component has a hard, black finish which can be filled / primed / painted any way you want.

I'm not a particular fan of Hammerite paint because it is quite expensive and it leaves a fairly unattractive finish that cannot be painted over - it's fine for things where appearance doesn't matter though. There is a spray version called 'Smoothrite' which gives a better finish, but it still cannot be painted over

Jeremy

[bryanhes]

Brian,

I have never used the metal ready prep. I always used the POR 15 after a good wire brushing, then painted over whatever I was working with. Most of the time it was slightly rusted floorpan or trunkpan. I would try to to both sides to totally seal the metal.

I was just reading it off the can. I don't know if the Metal Ready is a phosphoric acid. It does not say anything about it on my can. Just not to put it on a smooth or glossy surface because it may not adhere.

I guess as long as what we are all using works, thats all that matters right 

Bryan

[fortyniner]

Ive also heard about OSPHO but I thought it attacked aluminum. Is that not the case? Sure would be nice to kill rust in those hard to reach areas without harming aluminum attached to it.

[bevans6]

Google phosphoric acid and aluminium and read your fill.  You're find that it does attack aluminum but in a way some find beneficial.  It cleans the heck out of it, takes off the oxidized outer layer, and chemically brightens it.  People with those aluminium tool boxes and running boards use it to make them look bright and shiny.  I use it when I have to paint aluminium, it gives the paint at least a shot at sticking. 

Aluminium oxidizes almost instantly and forms a very thin layer of coating that protects the inner aluminium.  Anodizing is a kind of controlled oxidization on aluminium that forms a very hard protective layer over the base aluminium that can be dyed many bright colours.

[Dreamscape]

I used Rust Mort, probably outa the same vat! It turns the rust black and hard as nails. Just blow off the dust and slap it on!

[johns4104s]

Jeremy,

The hameritr you can get here in the US comes in many colors.

John