Electro Etching with Salt Water

I have been remiss... well that isn't the right word.... downright horrible about blogging.  I don't promise to do much better, but I do promise to try.

Thanks to Ann Sanicola,  I have been learning to etch with salt water and batteries.  I have done a lot of experiments, and thought others might like to see this


  • copper
  • resists (PNP, sharpie, stazon, oil paint, fingernail polish) anything to block the design from the etchant
  • brine water (distilled water boiled with kosher salt until it will not absorb more salt)
  • citric acid (find in the canning department of the grocery store)
  • 2 9volt batteries
  • alligator clips (2)
  • plastic container
  • copper wire
  • tape, I have used painters tape here, packing tape is good.

My experiment started with 2 containers, one with citric acid, one with just salt water.  I wanted to know if the citric acid made the etch go faster, like in Edinburgh Etch.

I started today with a batch of salt water and saltwater with citric acid (1/2 teaspoon) that had been used once.

etching 1.jpg

Notice that the right side is clear (citric acid) and the one on the left has a lot of sediments

Clean metal. Apply your resist (pnp etc)





 Attach a copper wire to the back of the piece with your tape. Cover the entire back and sides with the tape so that your metal doesn't etch away



Use a bare copper sheet (called a sink) and attach to the side of the container.  I just taped it, but a clamp would be great.  Part of the copper (at least  half) should be in the salt water solution


Clip the positive wire to the large wire and the positive side of the battery.

The negative wire to the copper sink and the negative side of the battery. 



The sink will start to bubble.  If it doesn't, check all clips.  If it doesn't bubble it doesn't work!!!

 At 20 minutes I had to clean the sink in the citric acid and I changed both batteries (which were not new, I had etched 1 hr with them the day before) because they weren't bubbling.

I checked the depth of both.  Needed more time.  I shook the plain salt water one to make sure all the copper was not clinging to the piece I wanted to etch.

at 50 minutes I took both out of the water bath, used baking soda to clean and then scrubbed off the resist.

pnp with salt water and citric acid, very clean etch!  depth decent

pnp with salt water, look at the etching around the edge, not smooth.  I know its hard to see!

etching 109c.jpg

Here is a side view of the saltwater bath. Left side has a lot of copper sediment, the right one with citric acid is cleaner...... much cleaner!

For my purposes I will use citric acid, but will use a different power source, one that can plugged in.  For teaching purposes I think 9volt battery will work.