Preventing Rust

I have to admit that part of this post is motivated by animus toward the “friendly” presenters who recommend obnoxiously expensive “nano” rust preventive measures toward the “friends” that they are making videos for. Let’s be honest, at least if you are cynical like me, they are making videos *at* people, not for them. You can skip the rest of the discussion that follows other than perhaps canceling the idea that maybe I just don’t have a very damp shop – and go down to the next header if you’d like. My discussion of humidity and circumstances follow because I’ve fielded at least half a dozen comments that “your methods wouldn’t work here”. Unless you’re getting a mist of salt water in the air, that’s not the case.

There is nothing difficult, expensive or time consuming about preventing rust on tools in the shop, and probably also not for metal surfaces on stationary tools. I used to have stationary tools – a jointer, a bandsaw and a table saw, and once in a great while early on, they would get a dot of rust. Let’s get something I guess set and clarified from the start – my shop is extremely humid in the summer. It is halfway below ground and it is not heated or cooled beyond whatever it gets from the ground and the surrounding house. Typical dewpoints in PA where I live are mid 60s to mid 70s, and on the hottest of days, my shop will reach 80 degrees. I *really like* this setup because whether it’s 95F outside or 0F outside, my shop will be in a narrower range -about 30-80F. You can work by hand in that range. But it does result in high shop humidity. At the moment, my shop is 86% humidity according to the digital hygrometer. I often hear people claim that they live somewhere hot and it’s 95 degrees and close to 100% humidity. Actually putting the dewpoint and temperature in a calculator should dispel that nonsense. RH is an interesting figure – when it gets really hot, it’s not common for it to be at or above 60% (95 with a 75 degree dewpoint is typical in the south – that’s an RH of about 53%). Really high relative humidity generally occurs when you take high dewpoint air and stuff it in an environment where the temperature quite so high. It’s 86% humidity in my shop because the shop is partially underground.

At any rate, like many, i started with a set of power tools and then mostly premium hand tools, and I ground the layer of patina right off of a lot of other tools. I spent a *lot* of time doing stuff like rubbing rust off of clean fresh cast and wringing my hands. It was a complete waste.

Here is My Recipe for Rust Prevention

• First, the lowest level of effort – Oilstones (wipe with high quality mineral oil if you insist on waterstones). I moved to oilstones a few years ago for a simple reason. They are faster to use. They don’t cut faster, but they’re faster to use and include much less screwing around. Once I did that, chisels and plane irons ceased rusting. period. If you are using oilstones, you can get the bulk of the honing oil off of tools such that it won’t mark tools easily, but it will take a lot of effort to remove every single little bit of oil protecting a tool surface. This is a good thing. You wipe oil off of the tool, it doesn’t mark wood, but you still have a layer of protection.
• Second, I use wax – on anything that I don’t want to constantly coat with oil. Paraffin on plane soles sort of covers those, and a Johnson Wax (RIP!) can or Briwax or whatever else for stuff you want dry, and then a 50/50 mix of beeswax and hydrotreated mineral oil makes a spreadable non-drying wax. Hydrotreated mineral oil is the stuff sold for all kinds of things – including as a honing oil. Could be bovine/equine supply, commercial kitchen cutting machinery, sewing machines, whatever it may be. These two types of waxes make a very persistent coating that will tolerate anything other than water laying on tools due to your absent mindedness. This is something you should avoid in the first place.
• For the worst, Light cut blonde or super blonde shellac – for anything that you find rust on, anyway, a very light cut of shellac – like 1 pound, can be wiped on. Just rub it into the surface of the metal – if you already have wax or oil on cast or steel, it won’t care – it’ll stick to the metal and then itself and if anything, push the oil to the top (exactly what happens in a french polish). The result should be almost invisible, and if you ever want to take it off, rub with an alcohol soaked rag, and it’s gone. If you put any shellac on metal and still have rust, something is amiss.

Wax your saws when you use them when they get in a bind. If you have new saws that you’re not sure about timing on use, use a light coat of paste wax – just wipe it on and wipe it off. You’re not finishing furniture.

One more comment about the oil and the comment “hydrotreated”. Hydrotreated mineral oils for cutting equipment, or if thicker, hydrotreated mineral gear oils, have had volatiles refined out of them. They will be clear unless someone colors them, they’ll have no odor (unlike some stinky honing oils) and if you put them in a container exposed to air, they won’t change over time, at least not in your lifetime. The princely sum for a hydrotreated commercial kitchen supply oil is all of about $18 for a gallon. If you get stuck shipping something, you might end up buying food grade mineral oil from amazon or somewhere else for about $10 more.

If you see a mineral oil by the gallon and you’re not sure – if it’s clear and for food use, it’s probably hydrotreated. You can google the SDS and confirm.

Too, the lack of volatile contaminants in hydrotreated oil doesn’t just keep it from stinking. It keeps it from drying, and means there will be no extra film like you might get from WD40 or something of that sort.

And that gallon of oil will find uses in a whole bunch of different things. French polishing, the oil and wax beeswax mix mentioned above, in an oilstone bath, and so on. It will take a very long time to use it. Of the things mentioned above, it’s the only extra purchase that I made to actually deal with rust, and my first gallon is almost used over 15 years, due to several things (like changing oil in an IM-313 oil bath) – but if just used for rust preventives, you’ll never use it all. That puts you $15 out of pocket. I’ll keep my gripe about commercial paste waxes to myself other than to mention that when I started, a pound can of Johnson’s was $5.95 and had a little bit of carnauba in it. The carnauba went away, then Johnson’s went away, and we’re left with paraffin wax-only garbage in a lot of cases for three times the price. Waxes that have 5 or 6% carnauba like blue label mowhawk wax fall into the category of a product that has almost no manufacturing cost, but those appear to retail now for $30+ tax or more.

If you have full fast changes in temperature…

….and a dirt floor in your shop or something of the like, what I’ve mentioned above will still work. If you find that you have something persistent that still causes problems, then the problem tools can reside in a box that shifts temperature less quickly. Temperature swings in my shop are moderated by being part of the way underground, but my tools have all been handled so much with oily hands from sharpening, or waxed in use, that there really isn’t anything that rusts unless I see water laying on whatever it may be out of laziness and just let it go. Since water is handy for grinding with a power belt grinder, it happens.

You shouldn’t be subject to people who want to market nonsense to you, but they’ll always be the most persistent. I’ve got cans of dry lube, bike chain lube, mutton tallow, and who knows what else – all in the original attempt to keep things lubricated. I can’t vouch for the tallow -the beeswax mix obsoleted it, but it could probably be made into a soap.

I really despise videos and other parroting of such about nano or graphene rust control or whatever the next flavor of the moment may be. My opinion is that all of that stuff is intended to give you the perception of value by a bunch of cliquey talk. One of the relatively famous guru youtubers made a pitch for it in the past ($70 for one ounce of the coating, without even getting into the nonsense “pre cleaning spray” and slippery after coating), and found rust on a saw that was put into storage. Using the discussion of the rust to come back and pitch it again. The video comes with the obligatory “sponsored video” upper left hand corner tag. It’s up to you to guess whether or not the second video was made because “it just worked so well”, or because there’s an underlying agreement that required more than one video.

It’s too bad this stuff isn’t called out a little bit more loudly. If the video maker would’ve applied 15 cents worth of thin cut super blonde shellac and returned later with an alcohol soaked rag to remove it, there would be no rust.