A natural patina that is allowed to form over time will always be a better stronger shield, but if you just can't handle the awkward splotchy stage of a fresh patina you can force a patina on your blade in just a few minutes and skip the months of hard work.
If you google this you'll find MANY different ways to do this. Different foods will effect different steels in unique ways, so if you'd like to nerd out on crafting a unique patina google stuff like "patina colors of different apples". It gets nerdy, don't say I didn't warn you.
Our two favorite methods for an easy even baseline patina are vinegar and mustard.
Vinegar
For a vinegar patina, you will need white vinegar, a tall container large enough to dip the whole length of the blade, a pot, and a stove. Vinegar will give you an even and very dark patina. It will also boost the contrast of the layers in the Damascus. Experiment with apple cider vinegar for a slightly different finish.
1. Prepare a container to hold the vinegar. It needs to hold enough vinegar to coat the entire blade. A tall skinny container is best so you need less vinegar to fill up high enough. It goes without saying, it also needs to be big enough to hold your knife blade. The handle can stick out.
2. Test run the amount of vinegar you need by putting your knife in the container and filling up with water right to the heel of the blade. The whole blade needs to be covered but the less the handle has to soak the better. Take the blade out and pour the water into a measuring bowl. This is the amount of vinegar you will need.
3. Heat the vinegar on the stove right until the point that it starts to boil.
4. While the vinegar is heating, get your knife cleaned up with alcohol to make sure all wax, oil, and food residue are completely gone, and tape off your handle with masking tape or painter's tape.
5. Place the knife tip down in your container and pour the vinegar in as it starts to boil.
6. Let the knife sit in the hot vinegar for 5-10 minutes. You are looking for an even, black coating on the whole blade.
7. Once the blade has turned black take the knife out and let it sit on the counter for 2-3 minutes to let the oxygen do its thing.
8. Take the tape off the handle and scrub the knife down with warm soapy water making sure to remove all vinegar. You can sprinkle the knife with baking soda to ensure all reactions stop.
9. Dry the knife completely with a soft towel
10. Give the knife a healthy coat of mineral oil and let it sit out on the counter overnight before using it again.
If you have multiple knives to do you can reuse the vinegar, just make sure to reheat it between knives.
Mustard
For a mustard patina, you'll want to grab some plain ol' yellow mustard. You can experiment with dijon if you live life on the edge. Mustard is a little harder to control than vinegar, but gives you control of the pattern and is a lighter effect on the blade.
1. Clean your knife with alcohol to make sure all wax, oil, and food residue are completely gone.
2. Tape off your handle with masking tape or painter's tape.
3. Grab a clean container that can hold your knife upright from the handle. If you can't find anything that works you can just lay the knife down on a paper towel but you will only be able to do one side at a time.
4. Apply a thin layer of mustard over the whole blade. You need less than you think. If you want a little extra character you can create swirls or any other design you would like. Note that this is a reaction between the acid in the mustard and oxygen so the edges of the mustard will develop the darkest so thicker is not better in this case.
5. Place the knife handle down in a container so the blade is up and getting oxygen around it. If you are using a paper towel only coat one side of the knife at a time. The back side will not get any airflow and just make a mess
6. Let the mustard sit on the blade for 30-60 minutes. Reaction time can vary a lot, so if you don't get the look you are after the first time just repeat the process until it looks just right.
7. Take the tape off the handle and scrub the knife down with warm soapy water making sure to remove all vinegar. You can sprinkle the knife with baking soda to ensure all reactions stop.
9. Dry the knife completely with a soft towel
10. Give the knife a healthy coat of mineral oil and let it sit out on the counter overnight before using it again.
Bonus Method - Instant Coffee
Follow the same steps as the vinegar patina but instead of vinegar use highly concentrated instant coffee in water. It should be concentrated to the point that it gets a little thick. The cheaper the better on coffee, we use good old maxwell house instant coffee. You'll want the blade to sit in the coffee for 2-3 hours before taking it out to clean and oil it. The result is a beautiful dark high-contrast blade, however, it does wear off quicker than the other two methods.
Note that all forced patina methods will equally react to the blades sharpened edge and will likely need to be resharpened after the process.
