The Amateur Crafter: Project 1.1a: Pushing Perfectly Patent-able Prodigiously Pleasant Patinas

I apologize for taking so long to write another article. Just recently I received a hospital bill for just over $1000. As you can probably imagine, I was a bit shocked. I’ve been on the phone in contact with their financial office to try and setup interest-free payment options. This has put several of the projects I had active on hold temporarily until the payment options are setup. Because I’m so cautious, I’ve got enough money saved up to easily deal with a huge bill like that, but it can still sting the wallet. Interest-free payment options would allow me to pay off the bill at a financially easier pace. Plus, doing so would put my projects back on track and allow me to continue. We’ll see.

So let’s have another go at some patinas. I’ve taken some the first “blanks” that some students and I machined on a CNC milling center. These were not shown in previous articles but they were among the earliest knife patterns we cut. The material is 1/8” precision ground O-1 steel. O-1 is oil-hardening steel that’s commonly used in industry where cutting edge retention and deformation resistance is high. Stamping dies and plastic injection molds are often made from O-1. Stamping dies need to be able to keep a good cutting edge and injection molds are subjected to high temperatures (due to melted plastic.) Some knifemakers prefer O-1 steel for their blades due to these properties. 

Since vinegar proved to be a good medium to force a patina on my last pieces, I decided to “kick it up a notch” with the corrosion on the steel by heating up the vinegar. I went to a Dollar Tree store and purchased the cheapest vinegar they had. Also, I bought a new pot to boil the vinegar in because I really don’t feel like using some of my good pots for this. Since I rarely use wire hangers, I bought a small package of those as well. Finally, some 000 extra fine steel wool from the hardware store finished up my supplies. I’ve a few other supplied used in this project but those were older purchases that I had around the shop.

I poured all of the vinegar into the pot and set it to heat up on my stove. Next I “un-twirled” the wire hanger at the hook and cut a section off with a set of wire cutters. I needed the “hook” end to pick-up and lower the blade blank into the medium. 

While the medium was warming up, I took some carburetor cleaner to the blanks and used a Scotch-Brite scouring pad to remove any existing rust and dirt. It’s not necessary to use “carb-cleaner”, a simple cleaning solution that can remove a bit of oil or dirt should be fine. I just happen to have carb-cleaner on hand. The pads can be purchased pretty cheap at most grocery stores or drug stores unless one simply wants to buy them from the hardware store. They’re usually a bit more expensive through the hardware store. So, by the time the medium was ready my blanks were cleaned and ready to go.

Once my blank went into the vinegar I immediately saw an effect. I didn't get any photos of it but basically I saw thousands of micro bubbles begin to pop up all over the steel submerged in the medium. Basically, this was the corrosion happening on the steel. I left the blank in the pot for about 40 minutes before removing to inspect it. And I have to say, I’m quite pleased with the result. The blade looks quite weathered as if it were an old knife that’s seen extensive use. I considered trying to grind an edge to give it a contrast look but I’m going to wait until I can purchase more belts. I may try later with just hand files, if only to see how it would look. 

Compared with the other blank the "cooked" blank appears quite weathered.

The medium level drops as its boiling and this produced a curious set of “ripples” along one side of the blank. The effect was unintended but I like the result.

After the patina I took the blank out and ran it under the faucet in my sink to cool it down. I checked its durability with the steel wool and the patina seems fairly deep into the blank. Then a liberal amount of oil rubbed on with a lint-free cloth to protect the blank from further corrosion. 

The cost of the project was low and I learned a lot from the experience.


32 oz bottle of vinegar - $1
3 qt cooking pot - $7
10 pk coated wire hangers - $1.35
Scotch-Brite scouring pads - $3
Extra fine steel wool - $3
16 oz WD 40 - $3
Total costs - $17 (approx.)

So basically the entire project was done for less than $20. Not bad at all considering the fairly small effort used to keep the cost down. Good thing too since I've been slammed by an unexpected hospital bill. One thing I learned, when boiling the vinegar, be sure to have more than what’s needed. I ran out and I couldn’t add more to the pot. As a result, the medium dropped in level. I should’ve purchased more vinegar but the final result still looks great. Another major point I learned about this process is the quite strong odor the medium produced from boiling. I expected some, but this was stout. Not only was it decidedly not pleasant, it would sting my nostrils and throat if it was breathed in. I think that I will add another equipment purchase to my shop wish list for the future. I’m going to invest into a well-made hot plate and extension cord, so that I can create patinas outside.