Let’s review the basics.
Restore, Repair, or Replace?
Before removing rust from an old power tool, it’s important to assess it for problems indicating the need for repair, as well as deal-breaker issues that make it more practical to replace it entirely. Chances are that if you purchased the tool new, you know it’s history, but if you’re considering buying a used tool, a comprehensive assessment is even more important.
Here’s a general safety checklist:
• Inspect the tool for cracks in the cabinet or housing
• Check for damaged switches or safety guards
• Make sure rusted blade attachments are solid and can hold a blade securely
• Examine the cord for damage from the point of entry to the tool to the plug
• Check the plug for cracks and missing, bent or broken prongs
• Assess if the tool is double insulated and properly grounded with a three-prong plug
• Look for black streaks near vents that indicate the motor may have overheated
Any of these issues could result in electrical shock. Worn cords can be replaced and old two-prong plugs can be retrofitted with safer three-prong styles, but tools with cracked housings, poor insulation, damaged safety guards and potentially bad motors aren’t worth the risk.
Choosing Rust Removal Products
If there’s too much rust to remove by hand with sandpaper or a wire brush, commercial rust removing solutions or DIY formulas can help peel away layers.
Light rust isn’t hard to deal with. Try applying penetrating oil like Liquid Wrench® or Kroil® to loosen the tool enough to let you tackle the rest with a scouring pad or steel wool.
For moderate rust, you can try repeated applications of oil and elbow grease, but a rotary tool with a sanding wheel or wire brush will be faster and more effective.
Moderate to heavy rust needs a stronger product. Consider commercial products including Boeshield’s Rust Free®, Evapo-Rust ®, or Kleen-Strip® have a good track record.
Before buying a product, however, it’s possible you already have the ingredients to make a home-made rust removing spray.
The most popular mixtures are:
• 1 tablespoon of oxalic acid in 1 quart of water
• 1 part muriatic acid to four parts water
If you’re chemical-sensitive or just want to take the safest, most natural route possible, try these DIY rust removing solutions:
• 1 part baking soda to 1 part white vinegar
• 1 tablespoon of baking soda and 1 tablespoon of lemon juice mixed into a paste
• Straight Cola — the carbonation plus phosphoric acid are a proven rust-removing duo
Chemicals to Avoid
Petroleum products like kerosene — a popular home rust remover for hand tools — and silicone spray can damage electrical components, so avoid them if you can’t adequately products those parts.
Preparation
Unplug the tool and remove any attached heads, blades, chucks, or bits. If a piece can’t be removed because of a rusted bolt or similar attachment, spray it down with a penetrating oil and let it sit overnight. Tapping on bolts and screws lightly with a hammer after oiling creates tiny openings that help the product seep in.
If it’s still stuck, it’s technically possible to disassemble the tool and cut the attachment off, but in most cases, there’s damage to the surrounding structure that will make it unsafe to reattach. In this case, it’s time to explore a new tool.
Since most rust-busting solutions are acidic and can cause both water damage and corrosion, simple precautions like wrapping cords in plastic and covering switches with tape only take a few minutes and prevent accidental damage. To protect interior components when working close to the head of tool like a drill or sander, make a drape out of a plastic bag. Slip the tool in up to your working area, and then tape it shut. If you can’t keep the interior of the tool moisture-free, consider forgoing chemicals and just use elbow grease.
Finally, drape the floor and adjoining surfaces with drop cloths to protect them from chemical splatter. Assemble safety equipment including goggles, gloves and a mask or face shield, and you’re ready to get to work.
Basic Process for a Rust Removal Solution
It’s important to follow the manufacturer’s instructions for use of commercial products. The following process is general and may need to take into account product-specific recommendations.
1. Remove loose rust with coarse sandpaper or a wire brush. An old paint brush helps clean out nooks and crannies.
2. Clean the surface with soap and water to remove unwanted oils or chemical residues and dry it thoroughly.
3. Apply the rust-removal product of your choice as directed.
4. When the product is done working, scrub the remaining rust away.
5. As you work toward bare metal, move from using wire brushes and coarse sandpaper to finer sandpaper or steel wool to avoid gouging the surface in a way that could compromise how the tool works.
6. When you’re done, coat the surface with rust-inhibiting oil or spray.
Preventing Rusty Power Tools
Everyone’s forgotten a tool in the rain now and then, but rust happens most often during routine storage. Here are some tips to keep your power tools rust-free:
• Dry tools after use
• Spray sensitive tools regularly with a rust inhibitor
• Use moisture removing gel packs or canisters in tool boxes and closets
• Run a dehumidifier in humid climates
• Store power tools indoors
• Bag tools in plastic for long-term storage
Removing rust from metal can be labor intensive, but it’s not complicated. Power tools are an investment, so why replace them when you can restore them?