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Ospho resists and retards rust while providing a sound base for paint. Recommended for use under oil base paint or primer. One gallon of Ospho covers 600 sq. feet. It dries overnight, makes a lasting bond between rusted metal and paint. (Note: Ospho is not actually a paint.) Contains phosphoric acid.
$17.26
$37.39
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Rusted Metals: It's important to note that Ospho is a rust inhibitor coating and not paint. Before applying, use a wire brush or wire wheel to remove loose paint, rust scales, dirt, oil, and anything else accumulated on the surface. After doing this, apply a coat of Ospho and let it dry (overnight). Once the surface is dry, you can paint over it.
How does it work?
Ospho transforms rust to iron phosphate, an inert substance. You will know its doing its job when the metal turns black. This means the chemical change has occurred. Very heavy rust can require two coats. Sometimes, a dry, grayish white powdery film develops. Simply brush off before painting.
Bare or New Metal: Make sure new metal is clean and free of oils or grease before applying Ospho. After drying overnight, the surface is ready for paint.
Galvanized Metal Treat galvanized metals differently, depending on how important appearance is. If appearance is important, apply a singe coat of Ospho and let stand for 30 minutes or until metal is etched. Flush with water or wipe to a smooth finish. Once dry, the surface is ready for paint.
If appearance doesn't matter, disregard the above. Simply apply a single coat, let dry overnight, brush off powdery residue, and paint.
Painting Over Ospho
Painting treated surfaces tends to yield more durable finishes, as moisture and oxygen are effectively sealed away from the metal. Unlike thick paints, Ospho is as thin as water, going on easily and providing much more coverage (about 600 sq ft per gallon).
This metal treatment works best with oil based paints and primers. Be sure to test before using with epoxy or latex paints. Suitable for use indoors or out.
Additional Instructions, Recommendations & Tips:
For best results, do not apply Ospho below 36 degrees F. Also, excessive moisture or humidity may cause longer drying times and increase powdery residue buildup.
BRAND:
Ospho
Type:
Rust Converter
Questions & Answers about Ospho Metal Treatment:
2013-04-08CHRISTOPHE CALLIAS asked: what about if i apply Ospho outdoor and it start to rain before the 24 hour drying period?
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2013-04-12WILLIAM WORKMAN: I doubt it will affect anything. Ospho is supposed to be washed off of new metal (with water) after 30 minutes. Old, rusty metal just needs to be dry (directions say overnight), I've applied it in sunlight, and been able to paint the same day.
It is not a paint, it chemically etches rust, making it inert, so you can paint over it.
2013-04-12ROBERT MAERSCH: From my experience, it will create a white powdery surface on the metal. A wire brush would clean that up nicely. I also recommend wiping the entire surface down with lacquer thinner before paint regardless of the rain or normal application. This seems to get rid of the slight film that ospho leaves behind. Apply some primer as soon as you can after the wiping down or you will start getting a rust skin on the raw metal. The treated rust turns black from the conversion.
2013-04-12RALPH TAYLOR: You may problems, you will get hard white powder that will have to be removed before you prime/paint.
As the primer/paint will not adhere to those areas.
2013-04-15RICHARD ROZANSKI: Ospho only acts as a corrosion remover while still wet. Any rainfall would serve to dilute any active Ospho from the part and reduce its effectiveness. Ospho will not prevent recurrence of corrosion, although it does help. You must topcoat bare metal to prevent corrosion from reoccurring. Be sure to scuff the parts before painting to avoid adhesion problems. For steel parts, I use Dupont 215S primer before top coating with an enamel paint.
2013-03-22A shopper asked: Is ospho better then a rust converter?
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2013-03-25JAMES RIFE: I think Ospho IS a rust converter. The phosphoric acid reacts with the iron oxide (rust) and forms a very hard blackish surface that is easy to then paint over or whatever you desire. It's watery thin and easy to brush or spray on, and it penetrates crevices etc. I've found it to kill rust dead!
2013-03-25JAMES MUSKAL: We have used Ospho successfully for a number of years on marine diesel engines. There is a chemical transformation. We haven't compared to other similar products.
2013-03-25ERIC ROSENTHAL: Ospho will remove rust and etch the surface so paint will adhere. Rust converters are usually just tannic acid based and will change the color of the rust without removing it. I would go with the Ospho over the converter
2013-03-26JOHN MENDELSOHN: I circulated 1:1 Ospho through heat exchanger on boat to clean and protect. Presumably there is no rust as the HE is copper-based.
J
2013-03-26MARK HESS: IT is a rust converter, changing rust to Iron phosphate. Where there is rust, after applying Ospho the surface of the steel will turn black. My experience with Ospho has been favorable. I used Ospho to prep a dozen 6 inch steel beams for painting. The beams had extensive surface rust. Not being able to sand blast the beams, I first knocked off much of the rust with a wire brush in a grinder before treating with Ospho. Two years later, the paint is still tight and looking just fine.
2012-12-31LINDA GARZA asked: can ospho be used in very humid weather ?
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2013-01-03LEE MORRISON: I don't know if Ospho can be used in humid weather - I followed the directions and the product worked fine.
2013-01-03ALLEN HIBBERT: Yes you can. I use it in Ohio with humidity between 60 to 90%.
2013-01-04KENNETH THOMPSON: when I use ospho treatment I spray it on the metal and scruh it in with steel and let it sit until it starts to dry and then I wash it off with water. That leaves me a very good surface to paint and seals the rusted area. Hope this helps. Kenny
2013-01-05HELEN FORTNER: Hi Linda
I live in Oregon where the weather is humid 9 months out of 12 and have never noticed a difference in the functionality of this product which WORKS AMAZINGLY WELL at removing rust and restoring the original surface. Hope that helps.
Helen
2012-12-11BOYCE LEFVENDAHL asked: Can I use Ospho in a pump up sprayer? Looking to treat a the underside of a truck I just bought from up north.
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2012-12-11Kevin V: You can use it in a pump sprayer. Just make sure you cover with plastic what you don't want to cover with the ospho.
2012-11-19A shopper asked: can i use this on a painted surface with rust spots appearing ?
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2012-11-19TERRENCE BOHN C/O AZTECH TECHNOLOGIES: You coulod try it, but I wouldn't recommend that. I'd imagine that the rust you can't see will be protected from the Ospho by the paint. My understanding is that this is made to be a prep for bare metal.
2012-11-19ALLEN HIBBERT: Yes you can. It will create a paintable surface.
2012-11-20KENNETH THOMPSON: I have done this, but it will soften the paint. Usually if I do this I am going to repaint anyway. I would not recommend it if you are not going to refinish. Good luck.
2012-11-20DOUGLAS JOUBERT: Not sure what is painted, wood, metal? I used it on a steel trailer hitch that was painted but had rust on the bolts and the welded joints. It cleaned up the rust real good but I didn't paint it and the rust came back. Used Ospho a second time and then after rinsing, cleaning, and drying I did paint it and it has lasted over a year.
2012-11-20FRANK HUNT: I used it directly on a heavily rusted but paint-free cast iron keel, so I'm not sure. I can't read the label because I no longer have the bottle. It did well for me but I found out the hard way that you have to paint over it soon (read the directions closely!) or the rust will come back through. When I couldn't get OSPHO I found Purple Power De-Ruster to be an acceptable substitute. For small areas I never want to mess with again, I use Rustoleum Rust Reformer.
2012-11-20FRANCES BURGESON: I have only used ospho on two surfaces- one being the rusted floorboards of an automobile, the second being the rusted screws holding the gutters to the house. The gutters themselves were not rursted only the screw head. They were brushed with ospho before the gutters were painted. This does not really answer your question but it is my only experience with the product.
2012-11-25MATTHEW COYLE: I would scrape the paint surrounding the rust spots to make sure that rust hasn't gotten under the paint. Loose paint, loose rust must be removed. I would also do a test patch to make sure the Ospho doesn't harm or discolor the paint.
2012-10-04SAM SMITH asked: Is it okay to use this on a high temp surface? I want to use on a motorcycle header and muffler and then prime and paint with VHT (high temp paint)?
2012-09-26A shopper asked: Can this be used under an aliphatic urethane?
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2012-09-28JOSEPH E. SULLENGER: I don't know. I flunked chemistry. What I have been told is that the main ingredient in Ospho is phosphoric acid which turns rust into iron oxide and essentially stops the rust.
2012-09-04S H asked: Galvanized Roof treated with OSPHO what type of paint is best? and why? I have a 40+ year metal building, heavily rusted galvanized roof, â??mostlyâ?? rusted. Once I have prep all panels and applied the OSPHO to the rust, what type of paint will stick best to the OSPHO and aged galvanized? I have heard oil base is not a good choice for galvanized steel, because with adequate drying time, the oil base paints can scratch off easily. One source told me to use Primer Rust Inhibitor (Primer Industrial Pro-Cryl Universal Acrylic Primer). Then on top of the primer to top coat it with DTM gloss paint (100% acrylic coating) However, any advice would be appreciated greatly. Thank you, SHandlin
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2012-09-05KENNETH THOMPSON: I'm sory to say I cannot help. I have only used it on auto and covered it with primer and basecoat and clearcoat. It work well like that.
2012-08-29MILT BAKER asked: I want to treat a rusty anchor with Ospho then coat it with Rustoleum "Cold Galvanizing Compound" which is 93% pure zinc, according to the label.
Anyone tried this? Any special prep between the Ospho (and letting it dry overnight) and spraying on the cold galvanizing compound?
I plan to spray on several coats of galvanizing compound according to instructions.
Milt B
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2012-08-29JAMES RIFE: I used to do exactly what you are planning on welded structures for use in a deep sea environment. Works great. No pre-paint prep required. Just make sure the Ospho has completely reacted with the existing rust and is completely dry and hard. Given the abrasion a typical anchor goes through in use, I'm not sure how long the spray galvanizing will last, but the combination of Ospho and zinc paint should inhibit new rust pretty well.
2012-08-29LONNIE VARNEY: Milt,
I've used Ospho with wonderful results. I've treated rusty auto frames. I use an air powered needle scaler to remove the heavy rust then a wire brush. I put Ospho in a pump spray bottle and soak it down, let it dry overnight, and wash off any residue. Again let it dry, prime and paint as usual and they've turned out excellent. I love the stuff. I'll be buying more, soon.
Lonnie
2012-08-29MATTHEW COYLE: I would strongly recommend washing down the anchor with soap and fresh water to ensure there are no salt deposits or other forms of contamination present. I found that I could spray on the Ospho using a hand held spray bottle for saturation coating and that two coats applied over two days are better than one. I tried the Ospho/cold galvanizing combination on my boat lift just last week. Too early to know whether it actually works but the Rustoleum appears to have held onto the Ospho so far.
2012-08-29BRUCE MACDONALD: Ospho is excellent for neutralizing rust. Haven't actually used it on an anchor, but I've used it in many other places on my steel boat. I've never found it necessary to let it dry overnight., though it certainly wouldn't hurt. Usually an hour or two is enough. The spray-on cold galvanizing compound is a quick fix but not very durable (and especially not on an anchor if you use it at all). You'll have much better results with Pettit Rustlok, which looks like galvanizing but bonds much better than the spray-on stuff. Brush on a couple of coats, as per the instructions. It will wear off with use too, but I guarantee better results than with any spray-on or Rustoleum product.
2012-08-29RICHARD BAUMGART: Hello Milt,
I am a believer in OSPHO. I have never been a fan of the galvanizing compound. OSPHO is a fantastic rust inhibitor. I have used a 2 part red lead epoxy over a double coat of OSPHO on a steel hull bilge. The finish coat was an oil base white. 3 years later,there is not a spec of brown rust. OSPHO does not say the epoxy undercoat is always a good idea but in my case it has worked quite well.
Just a 5 minute job,
Capt. Rich
2012-08-24STEVE WIESE asked: If I am removing old paint and primer from a car should I treat the raw metal with Ospho before I add any filler like Bondo?
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2012-08-24ALLEN HIBBERT: I have never applied Bondo over OSPHO before but I it does a very fine job of getting into the pores and then if you scratch the surface to add to the bonding capabilities I think you will be fine the pores will then be protected.
2012-08-25JACKY MEDLIN: if there is rust present, treat with Ospho for great results
2012-08-26RICK JONES: Steve,
If you are not going to repair the raw metal right away, I would treat the area with Ospho. You want the surface as clean as possible before you apply any bondo. Hope this helps with your project.
I have been using Ospho for years and I have not found a better rust killer, paint primer yet.
3/7/2013
5.0
Ospho rust killer
By Ken
from Coin, Ia.
About Me Casual Do-It-Yourselfer
Pros
Kills Rust And Keeps It F
Cons
Best Uses
Large Areas
Small Areas
Comments about Ospho Metal Treatment:
I use this product for a rust killer in old cars that I restore.
1/18/2013
5.0
I'll be placing another order soon.
By Scott
from San Jose, Ca
About Me Avid Do-It-Yourselfer
Pros
Works great
Cons
None so far
Best Uses
Rust Removal
Comments about Ospho Metal Treatment:
I restore old automobiles and this product is excellent for rust removal and metal prep.
11/22/2012
5.0
The best cleaner for steel and teak
By Jack
from Gilford NH
About Me Professional
Pros
Easy To Clean
Even Paint Distribution
Lightweight
Perfect For Cleaning Teak
Cons
Best Uses
Comments about Ospho Metal Treatment:
I used Ospho for over 22 years of maintaining cruising sailboats in the British Virgin Islands. Absolutely the best for maintaining the engine and all steel parts, including those which stained or rusted under load. While cleaning the support frame for teak swim platform I found it cleaned the teak platform better than anything else.
11/20/2012
5.0
Ospho saved my old galvanized gutters
By Phil the fix it guy
from Atlanta, GA
About Me Avid Do-It-Yourselfer
Pros
Easy To Clean
Even Paint Distribution
Cons
Best Uses
Kills Rust Saves Metal
Comments about Ospho Metal Treatment:
I am currently preparing the battery area of my sports car's engine compartment with Ospho. It is great and solves many elaborate issues that come from sanding and killing semi-invasive rust caused by battery acid. Also, about 10 years ago, I used Ospho to etch the inside of my 45 year old galvanized gutters. They had small holes in them and were very rusted. I used Ospho to kill the rust after using a wire brush, and then lined the gutters with plastic-based roof sealant and plastic mesh strips. Saved me close to $1000 for new guter sat the time and it lasted for years.
8/23/2012
5.0
it is AWESOME
By Bud
from Othello, Wa
About Me Avid Do-It-Yourselfer
Pros
Cons
Best Uses
Comments about Ospho Metal Treatment:
I used OSPHO on the underside of my 53 Dodge truck, what a great product! Overnight it turned from rusty red to dark black. I gave it a couple days and then topcoated with a 2 part spray on bedliner. Looks like new!!
5/22/2012
4.0
Excellent product
By mark
from virginia
About Me Avid Do-It-Yourselfer
Pros
Works well on rusty metal
Cons
Best Uses
Large Areas
Small Areas
Comments about Ospho Metal Treatment:
My brother in-law originally told me about Ospho. I sent him a bottle because he can't find it any longer.
6/29/2011
(1 of 2 customers found this review helpful)
5.0
I would buy this product again and again
By Rich but not wealthy
from Mt Juliet , Tn
Comments about Ospho Metal Treatment:
This is the greatest product for rust I have used it for rebuilding VERY rusty horse trailers in Fl. What great results. Hard to find in some areas.
6/28/2011
5.0
STUFF FROM OUTTA SPACE
By KAP
from NYNY
About Me Professional
Pros
Does the Job
Easy To Clean
Cons
SO HARD TO FIND YEA JT
Best Uses
Comments about Ospho Metal Treatment:
BESIDES BOAT USE, IT HAS HIGH VALUE FOR HOME AND AUTO PROJECTS. REALLY DON'T FEEL COMPLETE UNLESS THERE'S A BOTTLE OF OSPHO IN MY TOOL CHEST.
4/13/2011
5.0
Works as well as they claim
By Tech
from Columbus, Ohio
About Me Professional
Pros
Easy To Clean
Cons
Best Uses
Large Areas
Comments about Ospho Metal Treatment:
Used this on an outside afterburner that we have issues with rust. Product worked as they claimed. If you have a unit that heats and cools creating a haven for rust try this and you will be pleased.
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