Cleaning Cast Iron

Iron is used around the home in many places, both ornamental and functional; gates, fireplace grates, irons and tongs, railings, balconies, stairways, cooking utensils, scrollwork, radiators, stoves and locks. All of these get dirty from time to time and need the occasional cleaning. With a few simple tools and cleaning compounds you can have your ironwork looking clean and new again.

Iron, like other metals, is prone to rusting. The term rust actually refers to iron oxides formed by the reaction of iron and oxygen in the presence of moist air or water, leading to corrosion of the metal. That’s why your ironwork’s biggest enemy is rust; it can completely disintegrate a piece of iron over a long period of time, and in the short run, causes flaking and pitting visible on the surface. The first part of cleaning iron in your home is removal of all rust.

Rust Removers

Although a solution of water and soap can remove rust, given enough scrubbing, it is easier to use one of the special rust remover formulations that are available in hardware and auto stores. These are typically based on phosphoric acid and come in liquid or gel form. The phosphoric acid converts the iron oxides on the surface of the iron into iron phosphate, which can then be removed easily by scrubbing.

A wire brush, sandpaper or steel wool can be used for scrubbing. The manufacturers instructions should be carefully followed. If the ironwork being cleaned is antique or otherwise valuable, check to make sure the rust remover will not damage or corrode the metal beneath the rust.

Homemade rust removers can be made by mixing equal parts borax and lemon juice, or by using white vinegar undiluted. The specialty cleaner product CLR can also be used to clean some rust. I have also heard of people using a solution of 1 part muriatic acid to 10 parts water, although I think this would be a little too strong for ornamental ironwork.

Rust Cleaning Steps

First, get any loose clumps of rust, flaking paint and dirt by using a wire brush to scrub flat and curved surfaces, corners and crevices. Steel wool or silicone carbide sandpaper can be used on flat surfaces as well for this.

Next, thoroughly clean the object with rust remover, following the instructions on the product label. Smaller objects can be placed in a container and covered with liquid rust remover. Clean away residual compounds left from the rust remover and rinse the iron in clean water. Dry immediately after rinsing; rust will reform if you leave the iron wet.

If the iron is to remain unfinished and bare, apply a light coat of oil to it; mineral oil or if it is a cooking utensil, canola oil works well.

To retouch painted iron, make sure all rust has been removed and the surface is clean and dry. Apply one or two coats of anti-rust primer to start. You may need to abrade the bare metal with light sanding to enable the primer to adhere; refer to the manufacturers recommendation on the label. Allow primer to dry and paint with two or three layers of top-coating.

The majority of ironwork is either black or white painted, so there shouldn’t be too much difficulty matching paint colors. An oil-based enamel paint is the best type to use on ironwork, being more durable and washable. Apply the paint in thin layers, particularly on curved surfaces and scrollwork, since uneven paint can make the ironwork look even worse.