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How To Black Your Knife Blades

How To Black Your Knife Blades

Blackening  your knife blades

Whether you want to help protect your project from corrosion or if you just want your blades to look more tactical  or cool you may want to black out your blades. 

There are several different methods that can be used to darken up your knife blades. I will do my best in this article to cover some of the more common methods for blackening (also commonly referred to as etching) your blades. 

:Note: All products linked are affiliate links as I do not carry these products yet.


Ferric Chloride

Possibly the most common method for etching blades is through the use of a ferric chloride solution. Ferric chloride mixed with distilled water etches most steel including copper making it a very versatile method as well. The process is fairly simple and straight forward.

1. Pour ferric chloride into the chosen container for etching. I personally use a 4" PVC pipe with enclosed end and a cap.

2. Mix distilled water into the ferric chloride to desired ratio. A typical ratio is 3 to 4 to 1 water to ferric solution. The more water, the longer the etch takes but tends to come out softer.

3. Soak your blade in the solution for 45 minutes to 1 1/2 hours and check your etch. 

4. Spray the blade down with windex to neutralize the acid when satisfied.

Ferric Chloride for sale 


Super Blue

Super blue can be used in addition to a ferric chloride bath or as a stand alone bluing agent. It contributes to darkening a blade regardless of which route you take and is easy to find and use making it a popular choice. 

1. Prepare your blade by removing any oils from the making process or handling the blade with alcohol wipes.

2. Using a paper towel, rag, or qtip evenly apply a coating of super blue on all surfaces of the blade that you wish to darken.

3. Allow the super blue coating on the blade to sit at least 30 seconds. 

4. Rinse the blade off in cold water. This will remove the chemical compounds from the blade.

5. Buff the blade lightly with 0000 steel wool to remove any streaking. 

6. Reapply and repeat as necessary to achieve the finish you are going for.

Like some other methods listed here super blue will wear off over time and is not food safe but it can be easily reapplied and is a less expensive, readily available option.

 Super Blue for Sale


Instant Coffee

Instant coffee isn't so much of a etchant as a forced patina on the blade. There are many makers that will use an instant coffee bath to further darken steels to increase the contrast in damascus blades. A downside to this method is that it will wear off faster than some of the other methods listed here. 

I have looked at several methods but will outline what seems to be the best here:

1. Rub the surface of the blade with steel wool while applying moderate pressure. This may contribute micro scratches into the surface allowing the patina to solidify.

2. Mix a full container of any dark roast instant coffee (cheap is good here) with minimal amounts of water while boiling the water. You are going for an oil like consistency.

3. Place your blade into the mixture an allow for it to bathe for 3-4 hours. 

4. Check the patina on the blade and repeat as necessary.

It is important to note that this patina will likely wear off the blade pretty quickly as this is not widely considered to be a true etchant.

Instant Coffee for sale

Vinegar Etch

There are several differing view points on vinegar etching but there are consistent points that most people agree on. 

Step 1-Put a mixture of 1 part water and 1 part vinegar in a saucepan and bring to a near boil. While the water is heating scrub the knife (or knives) with dish soap and wipe dry with a paper towel.
Step 2- Put the knife in the pot, with the point in the bottom corner and the edge facing up, for five minutes.
Step 3- Take the knife out of the pot (using tongs or pliers, of course) and scrub with dish soap.
Step 4- Scrub the knife with 0000 steel wool.
Step 5- Clean the knife off with dish soap (again) and put it back in the pot the same way.
Repeat until it is the correct shade of gray.


Mustard Patina

Mustard can actually give you a pretty decent patina and has been known to create fake hamon's on blades. The patina will wear off in time but it is possibly the cheapest and easiest method in this list.

1. Clean your blade to remove any oils from you hands or from the production process.

2. Apply the mustard to the blade in any design you wish to achieve. When applying make sure to keep a good even consistency and not get it too thin as it will not patina the steel uniformly.

3. Wait15 to 20 minutes and remove the mustard by using warm soapy water. 

I feel it is important to note that you will have your most distinct patina at the edges where you applied the mustard where it interacted with oxygen. Because of this you can use mustard to create some really unique designs and patterns. Like other methods afore mentioned, this patina will wear off with heavy use.


Two options which I will not cover here are Cerakote, and Parkerizing which often require outside resources to achieve but create a much more consistent and durable result in protecting your blades from oxidization.

No matter what method you choose to darken your blades, remember to be safe, have fun, and always forge ahead.


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