This instructable will show you how to do a chemical oxidation on brass, bronze, or any copper alloy for that matter.
Why do it?
In this case the chemical oxidation (sometimes called patina, redox, or distressing; depending on the application) serves two purposes: Give the sax a unique vibrant look and protect the brass from further erosion. The color I was going for was a charcoal gray to black. I believe I was successful!
What you will need:
-Saxophone (or whatever brass/copper/metal you wish to use)
-Small Flat head Screwdriver
-Small Philips Screwdriver
-Fine grit sandpaper (400+)
-Multipurpose household cleaning agent
-Disposable coffee cup
-Rust-Oleum Clear Lacquer
Optional, but it will make your life a heck of a lot easier:
NOTE: if you don't have a sandblaster, you can make one with
Total cost for materials (not including the sax, compressor, compressor parts and stuff I already had): A little over $80 bucks
Step 1: Step 1
I used masking tape and a black marker to hold and label everything. I didn't lose anything, so I must have done something right!
Step 2: Step 2
The formula I used was provided from the Science Company. The formula is as follows
Sodium Thiosulfate... 6.25 gm
Ferric Nitrate... 50 gm
Distilled Water... 1 L
I decided not to use 1 liter of water since I was only experimenting. I used 1 cup. So the formula kept the same ratio, just a smaller amount. Also, I don't have a gram scale, so I used a dry weight conversion of grams to teaspoons.
1 liters = 4.22675284 ; for ease of calculations I rounded to 1 liter = 4.25 cups
1 teaspoon = 5 grams
1 table spoon = 15 grams
So I used 1 cup of (tap) water, 1.45 grams of Sodium Thiosulfate, 11.75 grams of Ferric Nitrate
Heat the water to 120-140°F, 50-60°C. I don't have a thermometer, so I estimated. Water boils at 212 °F (100 °C). I heated to the point where I saw the bubbles at the bottom of the pot (slightly steaming).
Now put on your disposable gloves.
Put the water into the disposable cup. Use the disposable teaspoons to add the Sodium Thiosulfate first, let it dissolve, then add the Ferric Nitrate. If you stirred the water with the spoon, DO NOT stick it in the chemicals! You don't want to contaminate the chemicals with a wet spoon.
Immerse the neck piece for 1 minute. When the neck piece is immersed, it changes to a purplish color after about 45 seconds. The color darkens quickly to the desired black in about 1 minute.
Pull the neck piece out and put it in the rinse cup.
I realized I did not have enough liquid to completely submerge the neck piece. I added about a cup to the solution, which diluted it some, but still got the job done in less than a minute. I also had to submerge the neck piece upside down.
As a side note, I also left a little bit of the lacquer on the neck piece in hopes of it reacting to the chemicals. It did not. This made me realize every bit of lacquer had to be removed, otherwise the brass does not react to the oxidation.
Step 3: Step 3
A side note: I did try to use industrial strength stripper. I used two different kinds and they both failed to remove any lacquer.
I used a 2 foot hose, added a small hole where I inserted the air compressor. The other end went directly into the baking soda.
I tried sand first, which was a bit too harsh since it left little bumps, and a bit too wet. So I decided to use baking soda which worked beautifully. As a warning, the baking soda gets EVERYWHERE so do it outside.
Once it was sanded, I rinsed it off in warm water and pat dried.
Step 4: Step 4
I made the mistake of not buying enough chemicals for the amount of water I needed, so I diluted the mix. I ended up using a little over 4 liters of water, with only enough chemicals for 2 liters. This simply meant it took longer than the one minute immersion. Actual time was a couple hours!
Heat the water in a pot then pour into the tub. Add the chemicals.
Even with the diluting, I still did not have enough liquid to submerge the saxophone. My solution to this was to tilt the tub and do half at a time.
The positive side of this is the slowly reacting oxidation yielded a beautiful color transition. The color transition was from a bright copper, to purple, to blue, to brown color, to gray, then finally to black. I contemplated pulling it out when it was blue. The pictures don't do it any justice.
Once that side was done, I flipped it and submerged the bell. If you look closely you can see where the mix did not completely cover the sax.
After both sides are complete, rinse the sax with warm water and let air dry. I hung mine upside down over night using a coat hanger.
A final note, since it took much longer to react, I did pull the saxophone out in the middle of the process. I carefully poured the mix back into the pot and warmed again. I threw the pot away once I was done.
Step 5: Step 5
There was a brown stripe on area where the saxophone was not completely submerged. I liked the way this accident looked, so with the scouring side of a sponge I scrubbed the stripe. I then rinsed again.
The next step is to start lacquering the sax. I used the Rust-Oleum spray on clear lacquer. The first coat was tested on the neck piece. Satisfied with the results, I used a ladder and a coat hanger to hang the saxophone to make lacquering easier.
Step 6: Step 6
After several coats, I hung the horn right side up to make sure I lacquered every inch thoroughly.
Total coats where about 5-7 on both the horn and the neck piece, which used up one can.
Not in any of the pictures are the thumb piece (not the plastic part), screw, and neck screw which where also sanded, dipped, and lacquered.
Step 7: Step 7
Clean keys with water and Multipurpose household cleaning agent. DO NOT get any on the pads, since the cleaning agent may ruin them.
Carefully assemble the saxophone back the way you started. Again I started with the neck piece to see what it looked like.
Step 8: Done!
I included a before picture again.