Updated: Nov 24, 2020
Ed is a do-it-yourselfer who is happy to share some of his ideas and experiences in this monthly column.
This month: A – B – C – Destroy the rust!
Sooner or later, each of us faces that daunting task of what to do with a metal fixture, a handle, some hardware, or most anything that is ferrous and has yielded to time and moisture. Rust is a formidable foe, and usually wins the battle. It may be the reason why a nice, unique furnishing or item is discarded and replaced with a modern replica, often of lower quality and made of cheaper material. This month, I will discuss one way to remove rust and revitalize something that you may have otherwise tossed into the trash, and I’ll use a very rusty pipe wrench as the example. (I wanted to save this wrench because it is large, old, and of much higher quality than many of today’s tools…)
Here’s what the wrench looked like when I discovered it in an old, wet basement:
I used a derusting method that I’m a big believer in — using a car battery charger, a solution, and some sacrificial metal. Essentially, it works by passing an electrical current through the solution, and in the process, the rust is removed from the rusty item, but the sacrificial item is destroyed. Interested?
You will need a plastic container large enough to fit the rusty item into, plus the item that will sacrifice itself. You can use a paint tray, plastic bucket, wallpaper wetting tub, a plastic garbage can, or whatever you have on hand. Set your item on it.
The sacrificial metal should be about the same size or mass as the item you’re working on if possible. For a door hinge, maybe a railroad spike — for the pipe wrench, I used a piece of angle iron. In other words, don’t expect to de rust a car bumper using an 8-penny nail. The sacrificial part can be iron or steel, but should not be galvanized or aluminum.
Place the sacrificial part in the plastic container. It should be as close to, BUT NOT TOUCHING, your rusty part. You can put pieces of a milk jug or a sponge between them to keep things separate if need be. If your sacrificial metal is bendable, you can even shape it to surround your rusty part. Things work best when the sacrificial metal is close to the rust.
Next, you’ll need to make up a solution through which current will easily pass. I like to use about a tablespoon of washing soda per gallon of water. “Baking” soda doesn’t work quite as well, but may do in a pinch. You’ll need to mix up enough to submerge your rusty item as well as the sacrificial metal. You can use warm water if you want, to help the soda dissolve better.
Ideally, some part of the sacrificial part should extend high enough so that when you pour in the solution, a small part of the sacrificial metal extends above the surface. That gives you a place to clamp on the POSITIVE side of your battery charger. If this is not the case, you should attach a heavy wire to the sacrificial metal so that you can attach the POSITIVE charger lead onto it, out of the solution. (If you don’t do this, the submerged clamp end of your charger will also act as a sacrificial metal, and it, too, will be destroyed…)
Clamp the NEGATIVE side of the battery charger onto your rusty part. Polarity is crucial, so double-check things. Remember, the sacrificial item will be destroyed in the process of saving your rusty part, so don’t use anything of value. Now, turn on the current. Usually, a 2-4 amp draw will work well enough to do its magic. Don’t try this with house current — only an automotive-type battery charger!
The solution will start to “bubble” soon, and shortly thereafter, will look pretty ugly. That’s good, and really has no effect on how things are working. If the part just needs a little rust removal, a few hours will work wonders. I left my rusty wrench in the solution for several days, topping it off as needed to be sure everything was properly submerged, and checking that the battery charger positive clamp had not become submerged. You can’t over-do things. The process only removes rust, not the good metal, so don’t worry about “leaving things for too long”.
When you’re ready to check things, unplug the charger and pull out your part. It will likely have a black coating, but the rust should be gone, or wipe right off. You can then rub most of the black off with a rag, dry it well, and then apply a protective finish of your choice, like gun oil, rust-preventing paint, or one of the high-tech rust “converters” that will protect against future rusting. The spent solution isn’t toxic or harmful, so you can just dispose of it. It may stain, however, so don’t toss it onto your nice blacktop driveway! Throw away your sacrificial metal part, and you’re done!
Here’s how the wrench turned out, after removal from solution, a quick wire-brushing, and coating with a protective finish.