Introduction: SALT AND WATER ETCHING
!!READ ALL THE INSTRUCTIONS AND SAFETY TIPS BEFORE STARTING!!
This is a simple and fast etching, also known as electrolytic etching, that is made without the use of polluting or poisonous chemicals: only water and salt, and energy.
Any comments or tips are welcome, as I'm just started and still learning, there may be better and safer way to do this project. This is just the way I learned in a jewelry class.
Step 1: WHAT YOU NEED
I will write more different supply you can use at the end of the instructable, like a tattoo machine, instead of the batteries (a way more earth friendly and efficient way to do the etching).
-a copper piece to etch;
-a transparent container;
-a flat long piece of copper sheet;
-INSULATED alligator clips;
-battery holder and wire;
-1/8" unshielded steel wire (do not use stainless steel), or carbon rod was also suggested here on instructable, as it is corrosion resistant; I actually learned to use stainless steel in a jewelry class, but I had few comments here about stainless steel not been safe to use. I need to admit that I don't have any knowledge about, so maybe research a little before attempting.
Step 2: SAFETY
I'm not responsible in any ways of damaging to items or people doing this project: use every safety steps known for every chemical or electrical projects.
-Turn ALWAYS off, or unclip, any electric device you are using, before touching anything, the water, any of the items in the bath, or touching any of the part involved in the project;
-Use gloves, not to get in contact with any of the chemicals or parts involved;
-Wear every appropriate safety gear.
-Do not use stainless steel.
-Do not ingest or smoke any of the components of the project :)
Step 3: PREPARE THE ELECTRICITY SUPPLY
This was my first etching attempt, so I used electricity from batteries, as I had them available, but in the future I will definitely only use some other device that doesn't need batteries, as they are pretty polluting (I will talk about at the end of the instructable). You can also use rechargeable batteries.
So take your battery holder, fill it up with D batteries, and add the alligator clips as in the photos at the end of the + and the - wires connected to the battery holder.
Step 4: PREPARE THE DRAWING
Cover the front part of the piece that you want to etch with electrical tape (or duck tape).
With the xacto knife cut away the part that you want to be etched (I just made a random figure to show how to do).
Make sure that the edge of the tape where you don't want the etch to happen are really well adherent to the copper, so any solution will get from the tape and the sheet.
Step 5: ATTACH THE COPPER COMPONENTS
Tape the copper long flat piece to the back of the copper component that you want to etch and make sure it touch it really well.
Cover all the back and the sides with electrical tape, making sure you don't cover any part of your design.
Step 6: PREPARE THE SALTY SOLUTION.
Warm up your water and dissolve the salt. The ratio of salt to water should be about 1 to 5.
Make sure the salt dissolve completely.
ALLOW THE WATER TO COOL DOWN.
Step 7: BENT THE STEEL WIRE
Bent the steel wire as in the photo: it should have an hook on one edge to hold to the side of the transparent container, and the other side wrap in to a large hoop, large as the bottom circumference of your container.
The hoop should touch the bottom of the container, so the middle straight part of the wire should be as tall as your container is.
Step 8: PLACE YOUR ITEMS
Place the copper piece in the container full of water and salt solution, bending the edge of the copper long piece like an hook, and hanging the piece of copper you want to etch in about the middle part of the container.
Place the steel wire inside of the container, on the opposite side of the copper, with the ring touching the bottom.
NOTE: the copper components and the wire should NOT touch each other.
Step 9: CONNECT THE BATTERY HOLDER
THE POWER SHOULD BE 5 VOLTS, DO NOT GO OVER 5 VOLTS.
Connect the alligator clip to the metal parts:
-ALWAYS BEFORE THE NEGATIVE TO THE STEEL WIRE.
-AFTER THE POSITIVE TO THE EDGE OF THE COPPER that hold the piece you want to etch.
Step 10: JUST WHAIT AND WATCH
If the device is working you should immediately see small bubbles coming out from the copper and the steel.
Than a yellow dust, than green. It always change a little bit the color.
The etching can take 20 minutes up to 45 minutes, depending on how deep you want your etching, how strong is the power, how wide is the part to etch, etc.etc…
Thiner cut in the electrical tape to etch will take longer to etch, wider exposed surfaces will etch faster.
I suggest to check your work every wile, so you make sure you have the desired result.
AGAIN: turn off any electricity before handling any of the components of the project.
Step 11: DONE
Done! This is the first piece we etched.
Wash well with water and soap, using gloves, all the metal components you used in the solution.
Step 12: LEFT OVER
Allow to sit the salt and water solution for a night.
You can reuse the salty water for your next project, just pour it slowly in another container, avoiding pouring any deposit.
Make sure not to touch the solution or the bottom left over with your bare hands, USE GLOVES.
Step 13: DIFFERENT WAYS
Instead of the battery holder you can also use:
-a tattoo power supply (they sell them now online as cheap as 20 or 30$). It is nice as you can adjust the power from 5 volt, but also lower. Higher is the voltage, faster is the etching, but lower is the voltage and more precise is the etching. REMEMBER: do not use a voltage higher than 5 volt. The negative always go first, on the steel wire. The positive always go on the part you have to etch.
-a 5 volt telephone charger. You split in half the cord, attach the alligator clips at the edge of each wire. (Also in this case make sure to know what is the positive and the negative wire. The negative always go first, on the steel wire.The positive always go on the part you have to etch.)
Instead of the electric tape, to mask your piece, you can use:
-nail polish (than you scratch the design you like with a sharp point);
-spray paint (than you scratch the design you like with a sharp point).
Step 14: !!!READ!!! USEFUL TIPS
This are some important things you should know and remember about this project:
-Make sure the salt is completely dissolved in the solution, and the solution is cold before use it. If the steel wire touch the salt it won't work.
-Make sure that what you are etching is not touching the steel wire in any place, if they do it wont work.
-Always attach the negative first. The negative is always on what you are NOT etching.
-Attach the positive to the piece you are going to etch.
-ALWAYS turn the power off before touching anythings.
-Wear appropriate safety gear (gloves, apron, eye wear…).
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Please be positive and constructive.
DO NOT use stainless steel! That bright orange precipitate is not only a dangerous carcinogenic salt, but also illegal, Just like Warholm pointed out.
Instead of stainless steel, use plain steel or better yet, iron which is easier to identify.