This process uses electrolysis to create a very organic pitted texture on steel. I “discovered” this process when I was using this method to remove rust from some metal sconces. After doing one successfully I hooked the clamps up backwards and created a mess. The sconce was covered in thick rust overnight. After cleaning the rust off I was amazed at the deep pits that were created. It was a texture unlike anything you can create with fire and hammer. I was hooked. I really opened up new ways to create solid privacy gates and wall hangings.
Here’s what you need to get started. 12 volt 10amp battery charger. Plastic bucket or tank. 3/8 rebar. I started with a 5gal bucket, then moved up to a 55gal drum. As my addition to etching increased I switched to a 250cal plastic water hauling container that is supported on the exterior with an aluminum frame. I’ve also built a custom single use tank from 2x12 lumber and plastic sheeting to etch a 4ft by 8ft picture frame.
Step 1: Line the inside of your plastic tank with vertical rebar spaced about 3 inches apart. These can be secured to the tank by drilling a small hole on each side of the rebar (at the lip of the tank) and using wire to “twist tie” the rebar in place. My 250 gal tank has a curved lip on top that overhangs the interior. I drilled 3/8 holes through this lip and pushed the rebar down through the holes so nothing else was needed to secure the rebar.
Step2: Connect all the rebar pieces together in a loop. For temporary tanks I use copper wire wrapped around each piece of rebar. Over time the copper and rebar oxidize and the electrical connection between the wire and rebar will deteriorate. For my permanent tank I welded horizontal pieces of rebar across the tops of the vertical rebar. This ensures a great electrical connection. You basically have a rebar cage hanging inside of your tank.
Step 3: Fill the tank with water. Add 1 tablespoon of washing soda per gallon of water. This is not a critical measurement so when in doubt add too much soda. I use a whole box for my 250gal tank. You will find washing soda (Arm & Hammer is the most popular brand) next to the laundry soap in any grocery store.
Step 4: Place a wood 2x4 across the top of the tank. From this 2x4 suspend your iron work in the tank so it is completely submersed. It must not have any direct contact with the rebar cage! If it does you will short your charger out. For small pieces I use hooks made from 1/8 round stock. For larger heavier pieces I bolt or weld on a piece of rebar. Note: if you use 1/8 stock and leave the piece in the tank for more than 3 days you risk having the hook rust away and break sending your ironwork to the bottom of the tank. A magnet bolted to the end of a stick is handy for getting small flat pieces out of a 250gal tank – not that yours truly has ever had to do this.
Step 5: Connect the negative clamp of the battery charger to the rebar cage. Clean the rebar of any rust so you get a good connection. Clip the positive camp of the charger to the piece of metal your iron work is suspended from. Note: Do not immerse the battery charger clamps in the water. This etching process also work s on copper and you don’t want to have to keep replacing the clamps.
Step 6: Double check that there is no direct contact between your ironwork and the rebar cage. If your charger has amp settings set it on the 10amp trickle charge. Do not use the 50 amp “Quick Start” option. Plug in the charger. You should notice a ghostly blue white film develop around your piece with in minutes. You will then notice lots of little bubbles coming off the piece and the rebar cage. Now leave it alone for about 2 days. Note: this process produces oxygen and hydrogen gas! Needless to say this should not be done indoors where these gasses could accumulate.
Step 7: Turn off the charger and remove your piece. I find that 48 hours give a good deep pitted texture on 1/8 thick or thicker steel. Longer time means more pitting. Thinner stock will develop holes so a shorter time may be in order. Hint: lots of small holes makes for an interesting light sconce.
Step 8: Your beautiful iron work is covered in a heavy coat of gooey rust. Most of it will come off using a scrub bush and water. I follow this up with a twisted wire brush on my grinder (wear a full face shield as these buggers throw off eye seeking wire strands). Using a wire brush by hand is usually not aggressive enough to get all the rust out of the pits. I have also used a sand blaster to remove the rust. This will give the iron work a very uniform flat finish so I prefer the wire brush. Cleaning the rust of with the wire brush throws up a bunch of fine rust dust so do this in a well ventilated place.
Step 9: I use several coats of Permalac lacquer to seal my ironwork. Add solvent dye to the lacquer for some great color effects. The pits take more lacquer/color for a wonderful organic look.
Step 10: Have Fun! Experiment and report back to me with your discoveries.
Notes: The rust off of your iron work collects on the bottom of your tank. You will need to periodically drain your tank and clean this sludge out. It is iron oxide. Experiment and find some cool uses for it. Do not let your metal hang down into this sludge. It prevents the metal from etching.
This is an electrical process and thus you need good electrical connections. I have found that as the copper wire on the battery charger clamps oxidizes the clamps with heat up from the resistance. Take a few minutes and solder the wire to the clamps.
In general electrons are lazy little buggers and take the shortest route in any circuit. What does this mean for you? Hang your piece in the center of your tank. If you hang it to one side that side will get a heavier etching. This also means that if you hang a large flat piece from corner to corner in a square tank the edges of the piece near the corners will etch a lot and the center will etch very little. This is because the center of the piece is father away from the rebar cage – remember electrons are lazy and always take the short route.
You can etch more than one piece at a time if they are flat and hung edge to edge. If you hang them back to back the sides facing each other will not etch. This may not be a problem if you are etching a wall hanging and don’t care about the back side.
If you mask off areas of the steal they will not etch. This allows for all sorts of design option. I use two things to mask off the steel. For crisp edges on your design use latex sticker material (scraps available at any sign shop). Peel off the backing and stick the material on to your clean steal. Use an X-Acto knife to cut out the design and peel off the latex on the areas you want to etch. If you have a design already drawn (or printed) on paper use spray adhesive to glue the paper to the latex. For fuzzier edges in my designs I use oil based paint. Apply it as thick as possible using a dabbing technique instead of brushing as brushing applies the paint too thin. The paint along the edge of the design will be thinner and thus will create softer fuzzy edge to the design.
As you turn the water in your tank into oxygen and hydrogen and it also evaporates just add more water. No need to add more washing soda as it stays in the tank.