Updated: Nov 10, 2020
After you’ve finished hammering out and shaping your most recent forging experiment, it’s time to “lock it in” by quenching the blade or tool so that it is hard enough to use and last. A quenching oil for blacksmithing could be many things, including dedicated quenching oils or miscellaneous oils you may use for your car or cooking. However, the quenching process can be incredibly delicate so choosing the ideal oil can be the difference between your creation breaking right away or lasting a lifetime.
The Different Oils You Can Use To Quench
The right choice for your quenching oil will depend on your desired hardness and the metal you are working with, so we’ve gathered some recommendations as well as insight into why these quenching oils for blacksmiths may work for you.
Commercial Quenching Oil for Blacksmithing
When it comes to quenching, it’s hard to go wrong with a specialized oil just for that very task. This commercial quenching oil for blacksmithing is made of mineral oil as well as additives that help to speed up or slow down the quenching process depending on the quality you select.
Though this 5-gallon tub comes in medium speed #100, there are multiple levels of quenching depending on your specific needs. If you want something faster for a harder quench, consider dropping to #50 or going up for a slower and softer result.
The negative of this option is that it can be harder to find locally and more expensive because it is made specifically just for quenching rather than multiple uses like the rest of our choices. However, you can buy it on Amazon and if you want one of the better options, consider a commercial quenching oil.
Automatic Transmission Fluid
This automatic transmission fluid from Valvoline can be used to quench steel, though it obviously isn’t made specifically for this use case.
Automatic transmission fluid (or ATF for short) is a type of mineral oil that, in addition to an unusual color, can come with some nasty fumes making it a problem for smaller and enclosed areas. The reason for this is because similar to motor oil, ATF comes with additives to protect the hardware of the vehicles since that’s the main use for the fluid. It can also be thicker than what is ideal for quenching, which may lead to overhardening.
While using ATF for quenching steel does have downsides, one of the best upsides is the price and availability. This product will be much cheaper when compared to more expensive choices such as commercial quenching oils because it can be used in your car or forge.
The UltraPro Mineral Oil from UltraSource is a reliable resource to use as your quenching oil if you don’t want a dedicated commercial grade quenching oil or don’t want to inhale potential ATF fumes. A wonderful upside to choosing to go with mineral oil as your quenching oil is being able to complete the process nearly anywhere – even your home.
Choosing to use something such as motor oil or ATF oils could be less ideal for a home environment due to the combination of smell and additives that can create potentially harmful fumes that you could accidentally inhale. Fortunately, mineral oil is both colorless and primarily odorless and doesn’t have any of the additives that motor oils contain.
When it comes to the speed of the quenching, mineral oil will be a slower quench when compared to other types of oils. This isn’t always a bad thing, but it really depends on the type of steel you plan on quenching. Some types such as 1095 steel require a quicker quenching oil, but other types such as 5160 or 52100 steel will be perfect for mineral oil – just make sure you do your research on your metal before buying for the best results. Or if you have scrap metal and need to figure out if it will harden check out this video.
Mineral oil is one of the cheaper and more available kinds of quenching oil you will come across, it’s possible the reason for this is because it’s used for a vast number of things such as treating wood, moisturizer, and many other things.
Looking for a wonderful smell in your forge? This pure coconut oil made by Golden Barrel is a great choice for your quenching oil, should you decide to go the vegetable oil route. Similar to mineral oil, vegetable oils come with the benefit of not polluting your house with odors and even filling them with nice smells – the smell of coconut in this specific case. However, while these oils are more home-friendly, you will also have to pre-heat it to about 120°F before using it for quenching due to a lower viscosity.
This product specifically is more expensive when compared to other vegetable oils due to it being pure coconut oil that isn’t overly abundant, with many uses such as on skin, in hair products, and cooking with food. However, generally you can expect vegetable oils to be similar to mineral oils and among the cheapest of quenching oils because of their availability in many forms.
Along with being normally greatly priced, you should be able to walk into nearly any general retailer and find a type of vegetable oil suitable for quenching steel, including canola or vegetable oil. It definitely all depends on the type of steel you’re working with, but vegetable oil is the most home-friendly quenching oil because of the lack of any odors or additives, and normally being priced well with maximum availability.
One last Important Tool You Need
Once you’ve got your blade forged and quenched, it’s important to check the hardness of the metal you’ve forged to ensure it is not too brittle from your quenching. This is one of the most common mistakes novices make, and also one of the most disheartening things to experience. To measure this hardness, a special tool comes in handy.
Hardness Test File Set
The TTC 6-Piece Hardness File Set is a beginner-friendly hardness tester that will work on just about anything that comes out of your forge. You simply run the file over the surface of your creation to test it, comparing your results to the included chart. Each colored file corresponds to a specific hardness level that will scratch the material if it is harder, giving you an idea of whether the blade is too hard or too soft so that you can make changes before it is time to temper the metal.
When it comes to choosing the best blacksmith quenching oil, much of the decision comes down to preference. If you ask around, most experienced smiths have their own preferred quenching oils (in addition to metal choices and fuel types) because they work for them. Aside from the potential health risks of inhaling dangerous motor oil fumes, every option we listed should work for a variety of uses, so be sure to consider all types of oils before you choose one.
If I had to pick a specific type of oil to go with, it’s hard to go wrong with any vegetable oils. They are clean-burning, either don’t smell or smell good, and are primarily affordable and available. You can also stock up on them and use any leftovers for cooking, making them a versatile option for the forge or kitchen.
If you are just starting out check out my beginners guide to blacksmith tools
Or if you are just getting into knife making? Look at my guide to all the many steps in forging your first knife.
-THE STAY AT HOME DAD
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