How To: Make Rust Disappear

By Scott Sidler June 19, 2017

how to make rust disappearRust sucks. Let’s not sugar coat it. Nobody wants to have rust on their metal tools or steel windows. It’s wood rot but on a different surface and it will slowly eat away the metal things you treasure most. But what if there was a way to make rust disappear? Sure it will come back if you don’t take steps to prevent it, but if you already have something that is seriously suffering from rust what can you do?

I’ve been fighting rust for years in the historic preservation business. Sometimes with great success and sometimes with huge fails. And since I like to pretend I’m some kind of crash test dummy for preservation I have been doing some testing in my shop to see how I can stomp on the head of rust and claim victory once and for all.

I’ll show you a couple of different options today. Some of them cost only a few bucks and others will cost about the same as your new Tesla. But all of them are rust destroyers in the truest sense. They each have their place for different projects and materials so it will depend which works bet for you. We’ll start with the simplest first.

Ospho

osphoOspho is a readily available liquid you can find at most any paint or hardware store. It is mainly phosphoric acid (yes the same thing in Coca-Cola) which when it comes into contact with rust (iron oxide) it chemically converts it into iron phosphate which is completely inert. Once the rust has been converted it can be primed and painted or otherwise sealed.

Ospho is caustic so you’ll want to make sure have eye protection and plastic gloves on when handling it. Also wash any spills off your skin promptly. Application is simple usually just using a disposable chip brush does the job and then wiping off any excess puddles after an hour or so of working time.

This works well for steel windows and other larger metal projects, but a lot of the time you’re looking to have the rust removed not simply transformed, right? Well, there is a way to use Ospho to completely remove any trace of rust.

The Ospho Bath

Pour enough Ospho into a plastic bucket (not metal) that is deep enough to completely submerge your rusted piece under the surface. Go watch a movie and come back. After a couple hours (depending on the severity of the rust the Ospho will have moved past converting the rust to iron phosphate and will have eaten it away and caused it to slough off. Any remaining rust can usually be cleaned off with some steel wool and mineral spirits.

Take a look at the old glazing point driver I restored with this technique. This required no scraping, sanding, or any physical labor other than wiping the surface clean at the end of a 4 hr soak in Ospho.

Sand Blasting

Sand blasting gets a bad rap in historic preservation circles, but that’s mainly because people use it the wrong way on the wrong surfaces. Used properly sand blasting is one of the best ways to clean and protect old metal. If you have rusted steel or iron then taking those pieces to a sand blaster can be just what the doctor ordered.

Softer metals like bronze or copper are usually not good candidates for sand blasting, but for steel and iron the process thoroughly cleans the metal of any rust, dirt and other contaminants. The other advantage of sandblasting is that it creates a uniformly rough surface on the metal which is a much better surface for primer and paint to adhere to rather than a super slick metal. This can greatly improve the adhesion and therefore lifespan of your paint.

You can get your own blasting equipment and try sandblasting things yourself, but in my experience it’s not worth the expense or hassle. Find a local sandblaster and drop it off with them because the cost is usually pretty cheap.

Lasers

Much better than Dr. Evil’s sharks with lasers on their heads, this laser can obliterate rust or paint on top of any metal. Using 1000W of laser power it creates so much heat that whatever you aim it at turns directly from solid to plasma or vapor. It is literally like those old sci-fi guns that vaporize things!

How’s it work? The system uses short pulses of laser light. When aimed at a metal surface, “the dirt layer and any oxides underneath will absorb the energy and evaporate.” The metal underneath will not absorb the laser energy, leaving nothing but a clean surface ready for welding or painting.

How much does it cost? Glad you asked Warren Buffet. You can pick one of these handy 1000W lasers up for only $480,000 or you can also get one of the little 20W lasers for only $80,000! Maybe it’s not for the rest of us, but maybe my kids will be able to afford one.

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So, now that you know how to make rust disappear you may want to follow up by checking my previous post How To: Stop Rust For Good. Between these two articles you’ll be armed for the battle of your life until you get to heaven where you can safely store up your treasures because there rust and moth do not destroy.

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