The Low Down on Rust | Best way to remove rust from tools

If you have tools, you’ve encountered rust! Here’s the low down on what’s causing your beloved tools to rust, the best way to remove rust from tools, and the best way to prevent them from prematurely rusting in the first place.

You pop out to the shed, pick up your favourite chisel and see shocking red stains across the previously shiny metal.

You reach for your beautifully repaired hand plane and see perfect replicas of your fingerprints in a rusty shade of orange – marring the once polished sides of the sole.

Your trusty adjustable wrench no longer moves with ease because the shifter is gummed up with those dastardly, dusty, and grainy flakes of red.

Any of this sound familiar?

Rust is something every owner of tools will struggle with at some point, but there are ways to lessen the struggle and save ourselves from some of the frustration!

How does rust form?

When we say “rust” what we are actually referring to is an “iron oxide.” Iron oxide occurs when iron is exposed to both oxygen and moisture. This exposure starts an electrochemical process which changes the material at a molecular level – essentially the metal fuses with oxygen molecules and creates the new material – Fe2O3.

Iron oxide weakens the bonds of the metal – which is why when rust is bad enough, you can literally break a once solid iron bar with your bare hands.

Rust on iron

An interesting side note: When iron oxide is created it takes up more volume than the original iron, which causes it to expand or “puff out” on the original piece. If you’ve ever seen cracked concrete that has metal rebar exposed, it likely occurred because of the expansion of the metal as it rusted. This is called “oxide jacking.”

How long does rust take to occur?

The first thing that comes to mind for many of us when we observe a heavily rusted item is “wow, that must be old.” This is why it is surprising the first time you return to your workshop and see a brand new tool already working its way towards looking like you picked it out of a box of your great-uncle’s old tools.

But, the reality is rust doesn’t take a long time to form. If you leave your cast iron table saw top unprotected with a piece of green wood on it overnight, you can expect to come back the next morning and see a thin layer of rust already formed! (oops… again)

A great video from the Canadian Conservation Institute shows how quickly flash rusting can occur when exposing a simple iron putty scraper to moisture over a period of 4 hours.

Two types of rust that I watch for

In the case of my tools, and antique restoration, there are two types of rust corrosion that I usually look for to distinguish how much I can expect to be able to restore the tool to usable order.

The first is surface rust. This is the orange, dusty rust that can easily be brushed or scoured off with minimal effort. While some discolouration of the metal beneath the rust often occurs after surface rust is cleaned away, it rarely affects the strength of the underlying metal to a high degree.

Surface rust on iron

Unfortunately, the only way to know for sure if it is surface rust is to brush it down to the bare metal.

The second type of corrosion is the more nefarious type – pitting. Pitting is a concentrated type of corrosion that forms holes or ‘pits’ in the metal.

To really understand the process that causes pitting, let’s go back to what causes rust in the first place and dig a little deeper.

In order for rust to develop it requires an anode (for us, a piece of iron that gives up its electrons), an electrolyte that can move the electrons (water, humid air, etc), and a cathode (another piece of iron that accepts the electrons.)

In the case of pitting, the corrosion is caused by a lack of oxygen in a particular area of the metal, which causes this area to give up its electrons more readily (an aspect referred to as anodic), and the surrounding areas, which have a bit more oxygen, are readily accepting of these electrons (cathodic). Since rust already requires the above exchange of electrons, this localised form accelerates the progression of the rust in a very concentrated area.

Because pitting occurs in a localised area instead of over the entire surface of the metal and extends deeper into the metal, it is often harder to detect and much more damaging to the integrity of the piece.

The results of rust pitting on a cleaned up plane iron
This photo of my Acorn hand plane iron shows the effect of pitting after all the rust has been cleaned away. Notice all the pockmarks in the metal!

Unfortunately, once pitting has occurred the only thing that can be done to “fix it” is to remove the rust from the holes and then fill them with epoxy or weld.

This isn’t the greatest option for our hand tools – but depending on how special/expensive your tool is you might be apt to try it.

Rust removal strategies

There are many ways to remove rust from your tools – from harsh chemical removers to regular household cleaning products, to more in-depth procedures like electrolysis.

Great: Vinegar

For many of my tool restorations, I have used plain old white vinegar. That’s right, the same stuff you have in your cupboard for salad dressings, or beneath your sink for cleaning is also phenomenal for rust removal.

To use vinegar as a rust remover, I believe the best method is soaking the tools in a tub with pure white vinegar. Some people add salt to the mix, but I have never found this to be any more effective than just vinegar – which means it’s just an added, unnecessary step for me.

I’ve left rusted tools in the vinegar anywhere from a few hours to a couple of months (I got distracted, okay?).

Vinegar used for rust removal on hand plane parts after two months
Two months of vinegary goodness

A couple of months was TOO LONG (oopsy). While the acid in the vinegar softens the rust and makes it easy to remove, it also eats at the metal – so it’s important to check your soaking tools regularly and remove them when the rust is easily scrubbed off with fine steel wool or an abrasive pad.

The metal on a plane iron eaten away by vinegar
You’ll notice the edge of this plane blade has lost a lot of metal from the acid.

After removing the tools from the vinegar and giving them a scrub, it’s important to thoroughly wash them to remove the acid from the vinegar. I’ve given them a good rinse in water as well as a dip and scrub in baking soda/water solution. The water itself works fine, but the added baking soda helps to neutralize any excess acid and the bubbling also works at getting beneath any areas of flaking that were left over.

Before photo of an acorn handplane being treated for rust with vinegar
Before and after photo of my Acorn hand plane after the metal parts went through a vinegar treatment.

After photo of rust removal using vinegar on an acorn handplane

I’ve soaked my tools in vinegar several times and always have good results (except for the above mentioned time when I got distracted and left them for too long) – granted it might take a bit more scrubbing after the fact than the following methods, but it’s cheap and readily available.

Better: Chemical rust remover – Evaporust

There are many chemical rust removers on the market, such as CLR and naval jelly,  but the one I have personally used and observed others using with good results is Evaporust.

There are a load of great things about Evaporust, but my personal favourite is that, unlike the vinegar and many other products, it doesn’t use acid to remove the rust. Therefore, I’m not going to run into the same problem of it attacking the metal itself if I leave it a bit too long. It’s also reusable, which means I can use it for several tool restoration products without worrying about too huge of a cost. And, it’s not as toxic or harsh as many of the other products on the market – I still wear gloves when I use it (because I’m paranoid), but Evaporust itself states that gloves and eye protection are not necessary.  If you’ve ever used other harsh chemical removers before, you know how caustic they can be – so this is a great bonus.

To use it, I simply give my tools a cursory scrub to remove loose flakes of rust and dirt – I mostly do this so that I don’t have to spend time afterward trying to really filter out the liquid before storing it for my next use. I then place the tools in a bucket of the Evaporust, put a lid on, and wait. I’ve never had to wait longer than 24 hours for fantastic results. It does leave a dark residue on the tools, but some quick polishing removes it.

Does the added cost make it worth it over the plain old vinegar? If you’re only doing a few rust removal projects here and there, don’t mind waiting longer for results, and putting a bit more work into scrubing after the soak, then I think the vinegar is more than adequate for your purposes. For me, the Evaporust has saved a lot of time and hand power in my restoration projects.

Best: Electrolysis

I’m convinced that electrolysis is the ultimate rust removal method. While I’ve only gotten to see the results of this procedure twice in person, I am excitedly awaiting the day when I can pick up a battery or charger and am able to use it for all of my rust removal purposes.

The process of electrolysis for rust removal requires passing a small electrical charge through your rusty metal. This charge stimulates an exchange of ions while the tool is submerged in an electrolyte liquid, effectively stimulating the exact opposite chemical reaction seen in rusting.

diagram of electrolysis for rust removal
Please enjoy my artwork

I was initially turned on to this process when I was lamenting some very rusted auto parts that I was dealing with, and my mechanic pal, who had all the necessary materials, told me to come over to see some magic. Jeeze Louise, it was magic. The rust just sloughed right off my headers and oil pan. I was immediately hooked.

You’ll need a car battery charger, a plastic or glass bin or bucket, washing soda, and a strip of metal to attach to the positive electrode.


WARNING:

It’s very important to have a well-ventilated area for your electrolysis procedure, as the process creates hydrogen and oxygen gas, which are highly explosive if ignited. Ensure that no sparks or open flame are anywhere near the setup, and that no spills of water can come into contact with the battery.

Rust Prevention

So, we’ve cleaned all the previous rust off and our tool is shiny and clean and ready to go right? You set it down on the table and turn around for two minutes only to find a thin layer of rust already developing!

After rust removal, the bare surface of the metal is especially vulnerable to flash rust. That’s why it is important to immediately protect it from further rust.

Fully restored Acorn handplane
After fully removing the rest and restoring this beauty, we definitely want to make sure we keep it that way!

We know that the combination of moisture and oxygen with the metal is what causes rust to occur. So, in order to prevent that, adding a protective layer to the metal that stops moisture and oxygen from contacting it is necessary.

My go-to when finishing the rust removal process is to wipe my tools with Camellia oil. I apply the oil on a rag which I store in an old, metal Altoid box – this makes it easy to grab and use whenever I am finished with using my tools. Camellia oil, unlike other machine oils, doesn’t have the tendency to stain the wood that you’re working with, which is a huge plus! After using any of my planes or chisels, I always clean them off and then wipe them down with the oil-soaked rag before storing them.

For my table saw surface, I avoid the use of oil as it easily attracts dust, instead, I thoroughly clean the surface with mineral spirits and then apply a dry, silicone-free spray such as Bostik’s Top- Coat or Boeshield T-9, I’ve used both with good results that tend to last longer than a paste wax. After spraying, I give it a good wipe down with a paper towel and I’m good to go!

Proper storage of your tools is another good rust-preventive strategy. Ideally, your tools would be stored in an area with very little moisture exposure. However, since I live in an area with heavy humidity and no environmental control in my shed, I’ve found the silica-gel packs (those little packs that come in the packages of many products and have “do not eat” written on them)  to be a good way to prevent moisture from getting at your tools if you are storing them in boxes– toss a few in with them and the packs will suck up the moisture in the air.

The silica gel packs lose their effectiveness over time, but I find they work well if being changed out on a semi-regular basis, or after “reviving” the packs by heating them in the oven to dry them out once they have lost their effectiveness. Give it a try!

If storing your tools in the open air, I find the best way to keep them from rusting is to hang them – while trying to keep them from touching any raw wood – raw wood just loves to seep moisture out onto your vulnerable metal tools!

You can kick rust to the curb

Rust is something as a tool user that you will always be trying to keep ahead of.  But, now that you know the strategies to prevent it, and the ways in which it can be removed, you have the power to keep your tools shiny and clean for years to come!

If you’ve found this information helpful, or have any questions or comments on rust removal and prevention, please leave us a comment below!

2 Replies to “The Low Down on Rust | Best way to remove rust from tools”

  1. Some great info here, thank you! I wish I’d known some of this before giving away some beautiful antique tools last year. They were so rusty I thought they were beyond help, but now I see that it might have been possible to restore them to their former glory.

    1. Hey Lee,

      I can certainly empathize with you, as some ten years ago I passed on a box of old tools that I didn’t think were worth hauling around with me anymore. Now I wish I still had them to restore. It’s hard to believe sometimes how much a little elbow grease along with the proper materials can transform an old tool to its former glory!

      Thanks for stopping by!

      Raff

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