Rust Busters

To a woodworker, rust is a four-letter word. Unless you live in the dry climates of the Southwest, you must always be vigilant against the red menace. With at least nine products marketed to woodworkers as rust removers and preventatives, we decided to see how well they work, and uncover which products deserve a spot in your shop. Before we could remove rust, though, we needed to create a consistent coat of it on two tablesaw extension wings. We sanded the wings to remove any previously applied rust protectants, then divided the surfaces into equal-size areas for each remover. We built the “wet box,” shown at left, and pumped moisture-laden air into the sealed box for 24 hours. After letting the rust stand for a day, we tested each of the removers and combination products (those designed to both remove rust and prevent its return) shown in the chart on the next page. During this test, we noticed that some of the freshly cleaned surfaces began to haze over with orange rust within minutes. This so-called “flash rust” proves why removing rust isn’t enough; in most cases, you need to apply a protectant right away.

To accelerate the formation of rust, we built this “wet box” and connected it to a cold-air vaporizer. The box’s clear acrylic lid allowed us to observe the progress of the test, while a drain hose allowed excess moisture to trickle away.

Proving the protectants

To test the effectiveness of rust protectants, we sanded, cleaned, and sectioned off another pair of cast-iron tablesaw wings, and then applied the products according to the manufacturer’s instructions. Next, we put the test pieces into the wet box, pumping moisture in continuously, noting when rust began to form and when the test area was completely rusted over. The series of photos, below, show the outcome and the clear difference in rust-prevention products. Remember that our tests accelerated rust formation far beyond what you can expect in even the most rust-prone areas of the country. (Much of the time in the wet box, water was actually standing on the test surfaces.) Even the protectants that failed in a few minutes in these conditions should last much longer under normal circumstances.

We applied a different rust protectant to each of the eight sections of these tablesaw extension wings and put them into the wet box. At this point, the wings have been treated but subjected only to normal humidity conditions.
Flash rust already covers three of four sections of the back wing, and has started creeping across the center two sections of the front wing.

Except for the section treated with Boeshield T-9 (right foreground), all sections have completely rusted over.

None of the products we tested did away with heavy rust with only one application. So for cleaning a large, heavily oxidized surface, such as a jointer table or tablesaw top, your first step should be to sand away as much as you can, then clean it with Empire TopSaver or Boeshield Rust Free. Both products proved easy to use with little mess. TopSaver also did well in the protection test, so it’s our top choice for a combination product. For small areas of spot rust, we found ourselves going back to the Klingspor Sandflex Blocks. The rust ring caused by an errant soda can on a humid day came off quickly with these abrasive blocks, then vacuumed away. There’s only one choice for protectant as far as we’re concerned: Boeshield T-9. After 24 hours in the wet box, the wing section treated with T-9 was almost as clean as when it went in. We were curious to see how long it would take for this area to rust over, as the others did in a day, so we continued to pump moisture into the box. After 380 hours in this extreme environment, rust finally overtook the T-9 protected area. ¿

Written by Dave Campbell with Dean Fiene

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