Preservation, cleaning, and restoration of blades – historical and otherwise

This is a guest article by Adam Severa. Originally, Adam posted this to Facebook, and I asked if I could host it on my blog to help preserve the article for posterity and for more easy reference and access in the future. He kindly agreed, and gave the article a little editing before sending it over to me for hosting on the blog.

I’m going to preface this article with a disclaimer: I’ve restored and repaired a fair number of vintage and modern knives and blades over the years, but I make no claims to be a restoration professional by any means. What follows is based upon my personal experiences and observations – you should always consult an actual professional if there is a chance your blade has historical or personal significance.

Now that that’s out of the way, chances are you have a blade in front of you. Maybe it’s a sword, feder, knife, or some other previously pristine sharp object that isn’t so pristine anymore. You want to do something with it, but you’re not sure what. The purpose of this article is to explain what comes next and the differences between preservation, cleaning and restoration.

The goal, when approaching any potentially valuable, family heirloom type blade is to PRESERVE it in it’s existing condition. All that discoloration on the blades, the wear marks, the blade with the bit of the tip missing… those are what we call patina, and it’s presence can (and does) add provenance and value to a knife or sword. Serious collectors would rather have an old Case or S.C.C. pocket knife with a cracked handle, a tipped blade or maybe even a missing blade than one some monkey with a sander tried to make shiny again. Think of preservation as stasis. You want the blade to look the same in 100 years as it does right now – not new, not deteriorated, the same.

That being said, “Dirt Ain’t Patina” and doesn’t add anything. You first need to CLEAN the blade to see if there is any potential damage or problems that need addressed. Keep in mind here that “clean” does not mean shiny and new. Clean just means removing surface dirt and contaminants. I have come across hundreds of blades that could have been valuable until someone “cleaned” them by taking sandpaper to it and removed everything that isn’t bare metal.

To clean a vintage blade (either to preserve it going forward, or to assess it’s condition) use the following:

• Mineral oil and a soft cloth – Mineral oil will clean off surface grime, sticker residue and things of that nature. It can’t hurt anything on the knife and will actually do wonders for old stacked leather handles. “Elbow Grease” only, no power tools or anything.
• You can use a wooden toothpick to get down into backsprings, pivots and small recessed areas. the wood on a toothpick is soft enough that it won’t scratch or damage the knife. Great at getting “gunk” out of a recess, including that green slime that inevitably forms when nickel silver, steel and brass interact.
• Compressed Air – Self explanatory. Once you dislodge gunk, you gotta get it out of the knife. Compressed air is good at that. A little extra tip that can help remove old grit and rust particles that build up inside mechanisms when I knife has been stored without oil in the pivot is to flush the area with mineral oil, then use the air to force the oil and all it’s accumulated debris out of mechanism.

Once you have a clean specimen, you need to determine if you want to PRESERVE it. If you do:

• I highly recommend Renaissance Wax,or RenWax for short. It’s a microcrystalline wax designed for use on nearly all materials by the British Museum. It will protect surfaces from the everyday “rigors” of sitting in a display case or safe. I have also heard (but not personally used) Walker Wax is a fine product. Collectors I regard highly swear by it. The application of either is the same. A little goes a long way, rub on, wipe off with a soft cloth.

If you have decided that Preservation isn’t enough, or there is some active rust or material that threatens to further damage the blade, then you need to look at some RESTORATION. Restoration aims to make the blade look new again and it’s almost always a subtractive process, in that material is removed by polishing, abrading or grinding. The following list is a progression of suggestions from least destructive, to the most:

• Pencil lead – Take a #2 pencil and heavily color on the active rust (the red or orange stuff). The lead is soft enough to remove some of the rust and not damage the steel itself. Wipe it down with Mineral oil when done. May take a few passes. Active rust can destroy a blade, so this is almost always something that needs to be addressed. The “Pencil” method is a trick I learned from an old collector. It’s the least invasive way to deal with rust.
• Flitz (or Simichrome) and a soft cloth – These are very mild abrasives, they won’t do much to the steel, but can be detrimental to handle materials should they get on them. It will remove tarnish, some surface patina and discoloration. This is really the first step beyond preservation into restoration.
• Rust Eraser – These are usually silicon carbide grit embedded in a rubber block. They come in a number of “grits”, so use the finest grit that works for you. They will “scrub” off patina and light rust. They will change how the finish of your blade looks.
• Steel wool – This comes in various grades of abrasiveness. Using it will remove discoloration and some mild surface corrosion. This WILL change how the finish of the blade looks. Because of the “fluffy” nature, it’s difficult to be precise with. Some people like how steel wool finishes look, I for one don’t. It looks like amateur hour.
• 3M ScotchBrite pad (fine) – A woven abrasive. It will remove surface corrosion and discoloration. Changes how the blade finish looks. It’s a bit more structurally stable than steel wool, so If you do it correctly (i.e. run it down the blade all the same direction, back to front) and you’re careful about getting it right up tight against guards or bolsters, this can look decent, almost like a satin finish.
• Automotive sandpaper – Used in progressively finer grits (start with 400, 600, 800, 1000, 1500, 2000) you can remove just about any surface problem. Use a hard backed sanding block so you don’t round off the grind lines. Like with the 3M stuff, sand only in one direction so you’re not imparting random scratches to the surface. Once you’re above 800 grit, start using some water along with the paper. This “wet sanding” will help keep the paper from clogging up. Some people go to 800 grit and decide they like the “handrubbed” look. If you go all the way to 2000 Grit, then you use something like Simichrome or flitz, it’ll look decent (not a mirror finish, but close). You can buy Micromesh abrasives all the way up to 12000 grit which are as close as you will get to a polished finish without power.

Any method you choose, it’s all about taking your time and being consistent. No power tools, please. Dremel tools are notoriously difficult to use to get anything resembling a decent polished finish, power sanders will ruin the blade temper faster than you can react, and a buffer is hands down the most dangerous tool you could use in a shop (as in could, and has, killed even professional knifemakers, See the tragic case of Gordon Dempsey).

That all being said, if you’re not familiar or comfortable working on something, then there’s no shame in seeking professional help with it. There are some people out there that are willing to take on restoration jobs, but you need to have a firm understanding of what these folk’s time is worth to them. You can spend more on a professional restoration than the value of the knife to begin with.

Also remember that anytime you do anything to a knife, aside from preserve it, you change the value, many times not for the better.