Protecting or Rehab-ing Metal Surfaces and Tools

Corrosion is a worldwide scourge, and nowhere does it hit harder than the bare metal surfaces of the expensive tools filling your woodshop. Everything from the cast iron top of a table saw to the delicate edges of planes and chisels will eventually fall victim to the relentless assault of the elements. Fortunately, it’s not a losing battle. Armed with a little knowledge and a few modern chemicals, you can make an informed decision and protect your investment.

Comments on Commonly Used Components:

The most widely known aerosol solvent in the world is WD-40. Developed in 1953 by the Rocket Chemical Company, it took engineers 40 iterations to create the ideal Water Displacement formula – thus the name was born. Over the years, people have used WD-40 for every imaginable task, including rust prevention. As beloved a product as WD-40 is, it also comes with a hidden danger. In the late ’90’s, the formula changed. While the older recipe could safely be sprayed around and even into electric motors, the new flavor includes an acid that will eat away the varnish on the windings and kill the motor. Aerosol being a rather random way to apply something, WD-40 now stays well away from anything remotely electrical in my shop.

Paste wax is a super-slick barrier sealant, as anyone who’s ever skated across a hardwood floor in their socks can attest. On the floor, it adds a protective layer to absorb the grunge we track across it. If you’ve ever had to strip a floor for re-waxing, you know first hand just how filthy that coating gets, and by extension, how well the wax is doing its job. Waxing metal is a completely different issue. A coat of wax on your car protects the paint. On the other hand, a coat of wax on bare metal does nothing but make the surface slicker. It offers no inherent protection from the molecular assault of a chemical reaction – which is what rust is – and in fact, will seal corrosion against the metal, thus causing the very thing it’s intended to prevent. Be careful to note that we’re talking about absolutely bare metal. Metal that’s painted is not bare. Metal that’s chrome (or otherwise) plated is not bare. And finally, metal that has been treated with some sort of protectant is not bare. This may be obvious, or it may sound like some sort of semantic game, but it’s not. If you understand the steps, then the solution makes sense. If all you have is a solution, then you’re left guessing at the reasoning that got you there.

Without intervening steps, barrier sealants can be counterproductive to what we’re trying to accomplish. Barrier sealants of any type can trap moisture between the sealant and the underlying metal. By way of example, if you put a coat of paint over a rusty or dirty surface, that’s what you wind up with: paint over grunge over metal. There is nothing inherent in paint which is going to clean or “fix” the underlying surface.

The How and the Why:

Insuring that your metal tools are ready for action is a two step process:

1 surface preparation

2 surface protection.

The first objective is to get the surface as clean as possible. Once that happens, then you have a known quantity – “clean” being known because as an individual, you know how clean you made the thing – and therefore a reliable base from which to start your protection efforts.

Because it’s the very first step, the most important rung on the ladder of protection is surface prep. Ideally, you want to start with the barest possible metal you can. If you are fortunate enough to have access to an abrasive blasting setup, this is the ultimate cleaner. Glass beads, plastic, and crushed walnut media are the best choices since they do not alter the surface dimensions of the piece. Never use sand or steel media. Sand will actually remove the surface of the object being treated (even if it’s only minutely), and use without proper respiratory protection will cause pneumosilicosis, a fibrous hardening of the lungs that leads to painful death. The process of abrasive blasting with steel beads is known as shot peening, since the impact revises the grain structure of the metal and has a hardening effect on the surface.

The most important thing to keep in mind about abrasive blasting is that it completely opens the pores of the metal surface that’s being treated. It is perfectly clean (aside from dust residue from the media) and vulnerable to absolutely everything. The normal amount of oil found on your hands will leave indelible fingerprints that will take more blasting to get rid of. By opening the surface of the metal in this fashion, you entirely ensure that the layer of protectant you are soon to apply will bond and penetrate on the lowest possible level. A side effect of bead blasting is the removal of tooling marks and a lovely light grey surface (the metal starts out white until it’s oiled). For those who treasure the mirror shine on their tools and tables, the soft matte finish will come as a painful shock.

If you have rust issues and you’re not in a position to scour your tools pneumatically, then you’re left with a host of more cumbersome alternatives. Corrosion is tenacious, and once it takes hold, it’s difficult to get rid of. There are various chemical agents, such as Naval Jelly, but depending on which you choose, they can have an adverse cosmetic effect, staining the finish of the metal. Most often, a wire wheel (or cup) chucked up in a drill or hand-held grinder is all you need to get back to bare metal. It’s infinitely more efficient than having to scrub away with a Scotch-Brite pad. Sandpaper is alternately too aggressive, or not aggressive enough, and is generally unsuitable for anything other than knocking off a light accumulation of surface rust. Once a surface has become pitted with rust, all sandpaper will do is reshape the surface.

Barring abrasive media, the most effective way of cleaning metal is some form of industrial solvent. There are many, and everyone has their own individual preference – including myself. Assuming that you want to go and find your own flavor, we’ll pause for a clarification of terms: “industrial” means something used by the cleaning industry, or by an industry which requires things to be clean before working with them. Unlike the marketing hyperbole found on consumer products, “industrial” is not a synonym for “strong”. In an era of frivolous lawsuits and uninformed (or downright stupid) users, products intended for use by the general public have been watered down to make them as non-threatening or non-destructive as possible and yet still (barely) capable of accomplishing their intended purpose. I have a bottle of organic aerosol fly spray that’s labeled “safe as a food additive” and I sincerely hope I never see it in action on The Food Network. Professional products are hampered by no such niceties. They are designed to do specific tasks – which means they can be dangerous – and they serve their purpose with wild abandon. You can pretty well guarantee that anything found in a store frequented by the general public (hardware, grocery, or super stores) will not be robust enough, no matter what the label says.

If you’ve been living in a cave for the past few years, you’ll be blissfully unaware of the trend of making all manner of things – everything from cleaning products to barbecue lighter fluid – from citrus byproducts. d-Limonene (pronounced “de-lime-o-neen”) is the major ingredient in the oil extracted from citrus rind. It’s powerful, has a nice fresh-squeezed scent, and is eco-friendly. Citrus-based cleaners come in a variety of strengths, even in industrial product lines. Having tested a number of these solvents, I’ve been surprised to find just how widely their effectiveness can vary. By far, the most impressive citrus degreaser I’ve used is Harvard Chemicals’ De-Sov-All. With a concentration of (only) 45% d-limonene, De-Sov-All chews through industrial packing wax like a herd of piranha. Recently, they’ve released an even stronger product called Conquer – a solution of 100% d-limonene with some emulsifiers thrown in. I have every intention of trying this stuff out, but I’ll need to buy more tools to adequately test its effectiveness. (Shucks.)

So why this obsession with industrial solvents? Simple – I am a tool user, in the most fundamental sense of the term, and I see absolutely no reason why I should waste my time digging a hole with a toothpick when I have access to a backhoe. No matter where they’re made, new tools are usually coated in cosmoline or some other sort of protective goo. If they’re made overseas and have to endure a long boat ride to market, this layer of protection can be quite a bit more resilient than a light coat of oil. As it happened, the table top and extension wings on my Grizzly 1023SL came drizzled in a liberal coating of something I’d never seen before: a slightly tacky-feeling wax-like substance.

While unpacking the boxes, we engaged in a brief and decidedly non-scientific test. We dumped a puddle of De-Sov-All about the size of a coaster on the top [fig 1]. A few inches away, we poured an equal amount of Greased Lightning’s Orange Blast [fig 2]. (This came from the local Big Lots, and should not be confused with an identically named, and equally ineffective solvent made by Superior Products. NB: The Orange Blast cleaner from Superior did absolute wonders when thrown into the shampooer.) As you can see from the pictures, the difference in effectiveness was dramatic. The industrial cleaner wiped away to bare metal. The drug store version softened the coating, but it would take a good deal of scrubbing and numerous applications to achieve the same results. So much for the effectiveness of consumer-grade solvents.

When it came time to get serious, the entire top was sprayed down with De-Sov-All and left to stand for about ten minutes [figs 3, 4]. The time interval had more to do with the fact that I had other things to do, rather than out of necessity. To save on paper towels – the waxy crud is fairly bulky – a plastic paint scraper was used to trowel off the waste. Another coat of degreaser was applied, and this time, the residue was removed with paper towels [fig 5]. To test and demonstrate the effectiveness of the cleaner, a third coat was sprayed on. This time, a clean white shop towel was used to wipe down the surface [fig 6]. You can see both the towel and the results in the last picture.

All in all, the process was quick and pain-free. The most difficult part was getting into the recessed cuts of the T-shaped miter slot. A wire toothbrush would have been perfect, but all I had handy was paper towels. As you can imagine, they didn’t stand up well to being jammed into a tight, sharp cornered recess. Total time, including goofing off and taking pictures – about twenty minutes. Total effort – minimal at best.

Being in something of a hurry, I decided to stop the cleaning process with the citrus degreaser. To get an absolutely clean surface – remember we’re talking about shop clean not surgically clean – you could wipe the surface down with metal prep agent from your local auto body supply shop. This solvent is used to remove any trace oils (as from fingers), dust, etc. that might ruin an otherwise quality paint job. It is the final step of cleaning before paint is laid down. It’s not a cleaning product, in the conventional sense. It’s not cheap, but its work is absolute.

Surface Protection:

Now that we’ve stripped the metal bare, the next step is to protect our vulnerable surface from the elements – the sooner, the better, since its vulnerability is comparable to that of a lamb tottering its way across the Serengeti. Water displacing solvents, as a general category, work by insinuating themselves between moisture and the underlying metal. How they manage to do that, and what else they do after they get there is determined by the sophisticated recipe of the product. As with the cleaners, there are a variety of products, each possessed of varying degrees of effectiveness.

In my experience as a “shopkeeper” – and this echoes similar comments from pilots, sailors, and other diverse users I’ve known – Corrosion Technologies’ CorrosionX falls into the rather broad category of “invaluable”. Developed for NASA and the military, and used extensively in marine applications, CX is a unique and largely niche product that should be part of every woodworker’s shop. (To give an idea of how thoroughly it’s been tested and qualified, the aviation flavor of CorrosionX meets the Department of Defense standard (Mil-C-81309E, Type II) for application to airframes.)

CorrosionX forms a molecular bond with the metal, spreading to a minimum thickness of .0003″ in much the same fashion that oil disperses and stretches over the surface of water, displacing moisture and contaminants in the process. It’s freaky to watch, but it does actually work as advertised. We sprayed a bit of CX onto the grooved edge of an 8″ pulley – about 2″ of coverage – and then forgot about it. In less than a week, that little spot managed to creep about halfway around the circumference.

CX comes in two forms: an aerosol and a liquid. Though I started off using the aerosol – that’s all I could get locally – I think I’d prefer to work with the liquid. Aerosol may be ideal for getting into tight areas like screw holes and such, but applying it to a large flat surface is somewhat problematic. CX lays down fairly thick, so you wind up having to wipe it around with a cloth, and there seems to be quite a bit of excess (waste) with the aerosol. After the initial application, the natural dispersing tendency will take care of the rest.

Having taken the proper steps to prepare and protect my tools, I’m confident that they will remain in excellent condition. The only additional thing I might consider doing, is to throw on a couple coats of furniture grade (i.e. no silicone) paste wax. It provides a nice, slick surface for sliding wood around – and besides, old habits die hard.


De-Sov-All can be found in janitorial supply shops and online.

If you have problems locating CorrosionX, it is available through the manufacturer’s website:

The EPA’s IRIS database has technical information on d-Limonene (CASRN 5989-27-5).


1 Initial De-Sov-All test spot: a small puddle left to stand, then wiped off with a papertowel. [Photo by author.]

2 De-Sov-All test repeated with Orange Blast: poured on, left to stand, then wiped off. Marks from the plastic scraper can also be seen. The difference between the performance of the two products is substantial. [Photo by author.]

3 Table saw top well-coated with De-Sov-All. [Photo by author.]

4 Detail of surface during the soaking process. [Photo by author.]

5 Surface of top after troweling off the residue with a plastic scraper. The scraper was used more like a squeegee than for its chisel-like ability. [Photo by author.]

6 The final wipe. The towel is shown work-side up to show how little material was left after the second wipe-down. [Photo by author.]