Yes, mineral oil can be safely used on hand tools to protect blades and metal parts from rusting. Using a soft rag, apply a very thin film of mineral oil over the metal surface after use. Mineral oil does not go rancid or oxidize.
The best types of mineral oils to use are:
- Any brand of pure mineral oil
- 3-in-1 Oil
- Starret Precision Tool Oil
3-in-One oil is produced by the WD40 company. It contains about 98% low-viscosity mineral oil (also called pale spindle oil), and about 2% citronella oil and a corrosion inhibitor. The name was given to imply that it is a lubricator, a cleaner and a protector in one oil.
Starret Precision Tool Oil, produced by The L.S. Starrett Company, contains about 80% mineral oil. The remaining 20% is withheld on the MSDS (Materials Safety Data Sheet), due to trade secrets.
Not only does mineral oil help with rust prevention, it has a number of other uses in the woodshop.
Additional Uses for Mineral Oil
Since we are talking about tools, mineral oil is great for preserving and protecting exposed wood tool handles (non-varnished). After cleaning your blade, flip the tool around and apply a generous coating of oil to the handle. Let it soak in for 5 – 10 minutes. Rub it briskly and let it rest overnight. Repeat this procedure, as many times as you desire to protect the handles. Mineral oil is a favorite among people who are concerned about toxicity and being in contact with it for prolonged periods.
And speaking of being non-toxic, mineral oil is also food safe. Go ahead, use pure mineral oil (not 3 in 1 or Starret) anywhere food is prepared. You know how babies treat everything as a potential food source? You can finish handmade blocks and baby toys with mineral oil. Then there will be no danger if they decide to try a few bites.
Finally, for whatever type of project you are completing, mineral oil provides a beautiful, natural finish. It helps to repel liquids, juices and food particles.
Some people prefer not to use mineral oil. There are plant derived oils that work very well in the wood shop.
Other Oils Recommended
Camellia oil from the seed of the camellia plant was used for centuries to protect samurai sword blades. Jojoba oil, another plant based oil is also a favorite amongst woodworkers. The benefit of these oils is that they are not as volatile as other oils. They do not spoil as quickly, and some prefer these oils, because they are safer on their skin. Now, a little money saving tip: find these oils where essential oils are sold, rather than at woodworkers’ supply locations.
Whatever oil you choose, the main reason you are using oil is to prevent rust, one of the biggest enemies of hand tools.
How Does Rust Form?
Most tools are a combination of iron (steel) and other metals that make the iron more stable. These combinations of metals make the steel less easily combined with oxygen causing iron oxide (aka rust). But rust can still form when the conditions are just right.
Rust does not need much to get started. It only needs is a bit of water, and some air, specifically carbon dioxide in the air. When the water hits the iron, it grabs a little carbon dioxide and creates a weak acid called carbonic acid. The iron molecules break down, while the acid is being formed. The water molecules break apart into their separate components: hydrogen and oxygen. The freed up oxygen attaches itself to the iron molecules. This creates iron oxide, resulting in what we see as a rusty corrosion.
If you love hand tools, people may give them to you. You may be find them at garage sales. Or you might find them by the side of the road for trash pick up. In many cases, they won’t be in great shape, so your first project with them will be cleaning them.
Cleaning Rust Off of Old Hand Tools
There are two methods for cleaning old hand tools. You can use good old fashioned elbow grease. As a hand tool woodworker, your elbows should be in great shape for that. For stubborn spots, you can also use an orbital sander or a wire wheel on an electric drill.
The second method is soaking them in mild acid, which helps clean tight areas.
In these methods, the common factor is applying a protective coating after the tools are cleaned. Here are the two methods with materials list and step by step instructions:
Method 1 – Elbow Grease
- Latex or nitrile gloves
- Work gloves
- Safety Goggles
- Steel wool, scouring pads, or coarse sandpaper and fine sandpaper
- Dish detergent
- Options for stubborn rust: kerosene, wire wheel attachment, electric drill
- Mineral oil or related products (as discussed above)
Put on your safety goggles and nitrile or rubber gloves. Scrub the tools in water and dish detergent to remove all the loose dirt, oils and grease. (Of course, Dawn dish detergent is great for breaking up oil. We don’t even get a kick back for mentioning it.)
Using the most coarse abrasive material that you have in your arsenal of supplies, scrub until all the rust is gone. Then use finer grit to buff out any marks left by the rust and by the coarse sandpaper. (Don’t forget your work gloves.)
If the rust spots are stubborn, then apply some kerosene. Wait a few minutes and then buff away with a wire wheel attachment on an electric drill.
Buff all the metal with one of the mineral oil products. Then put it away in a clean, dry, dust-free cabinet or tool chest.
Method 2 – Oxalic Acid (mild acid)
- Rubber gloves
- Safety Goggles
- Dish detergent
- Large plastic container
- Oxalic acid (purchased at any home improvement or hardware store)
- Mineral oil or related products (as discussed above)
- Scrub the tools with dish detergent and water to remove grease and dirt. Make it free of any oils, grease and caked on dirt. This allows the acid to have full contact with the rust.
- Put on your goggles and rubber gloves, continuing to wear them to the end. Set up in a well ventilated area, preferably outside or where doors and windows are open. In the large plastic container, add water and oxalic acid with the ratio of 3 Tablespoons of Oxalic acid to each gallon of water.
- Submerge the tools in the water. Make sure the metal portions of the tools are completely covered.
- Soak until the rust is gone. It will take approximately 20 minutes, more or less depending on how corroded they are.
- Rinse well. Dry very thoroughly. Buff with a coat of mineral oil and put away in a clean, dry cabinet or tool chest.
The best way to deal with rust is to not allow it to form in the first place. Once it starts it spreads and grows rapidly. As the iron begins to create course surfaces, there is more area for moisture and dust to accumulate. This creates more favorable conditions for the continuation of corrosion.
Keeping hand tools rust free is of utmost importance, to maintain many years of woodworking. And preventing rust is much easier than removing it, which can be a tedious, and tiresome job.
Preventing Rust on Hand Tools
- Use your hand tools to make a custom designed, wooden tool chest. Moisture is absorbed by the wood and keeps the tools dry. Depending on your space and your tool collection (or “wish list” collection), you can build a full cabinet or chest. Be sure all joints, doors or lid fit well, in order to minimize moisture. And for the same reason, when not in use, always close the lid or doors.
- store tools in a clean, dry, dust-free place. The key words are “dust-free”. Wood dust and standard dust that floats around households tend to absorb water, so dusty tools are prone to rust.
- Collect the silica gel packs that come in almost everything you buy (vitamins, dry food, electronics, shoes, etc). Drop them in your tool cabinet or chest.
- For small items that are not used frequently, seal them in a zip lock bag with a mothball. Oxidation is inhibited by camphor in mothballs.
- For a stationary tool chest or cabinet, you can purchase a goldenrod dehumidifier. The device is simply a small convection heater that will that moderately warm your cabinet. This will keep the surrounding area above dew point, preventing condensation. This, in turn, prevents formation of rust. An added bonus is that it also prevents molds and mildews.
- Keep your shop clean. Yes, just like your mom told you, you have to clean up your messes. Sweep up your sawdust, and dust your tools.
- Never put tools away with dust on them. Don’t use your own breathe to blow the dust off (even little bits of moisture can start rust). Wipe off the dust with an oily cloth.
- After working with your tools, dry them and apply a rust inhibitor, such as mineral oil, as discussed above. This will provide a thin coat of protection between the metal and moisture . It will minimize direct contact with air (remember what we said about carbon dioxide in the air).
- Control the climate of your woodshop with a dehumidifier. These are simple devices that pull surrounding air over a condenser. The moisture turns to water on the condenser and drips into a bucket. Or you can set it up to drain into a slop sink or drain.
As you see much can be done to care for your tools. The old adage still holds true: “An ounce of prevention is worth a pound of cure”. We hope you have learned a lot about the best oils to keep in your shop. As well as using oils for other purposes, and the care and maintenance of your hand tools.