Making Bookplates with Electrolytic Etching
Part II: Preparing the PlatePart III: The Etching EquipmentPart IV: The Etching Process and Final Remarks
The Etching Tank. You want a way to attach your work piece to the positive lead of your battery charger, and suspend it in a bath, parallel to a grid of metal to which you attach your negative lead. You want to do all this securely, because if the positively and negatively charged parts are allowed to touch, you’ll have a short circuit with the usual hazards to life and limb. Here’s my setup:
'& More' being the operative term here.
I bought a cheap plastic pitcher and a grill for a barbecue pit. I cut the grill down to size and attached it to the sides of the tank with some wire. I made a frame to attach the work plate to by gluing together some paint stir sticks. I’m always out of paint stir sticks, because they’re so damned useful for so many things unrelated to stirring paint. You know how people bring a bottle of wine when they come over? I have wine, bring paint sticks. Here’s the frame to hold the plate. The tape will hold up in the bath, if you use duct tape instead of gaff tape.
See the bulbs and sockets attached to the wire? That brings us to the next part,
The Electrical Circuit: You’ll attach the negative terminal of the battery charger to the barbecue grid (cathode), and the positive terminal to the work plate, according to the following diagram:
In between the two terminals, you’ll probably want some additional resistance. The reasons for this are twofold. First, if you do accidentally touch the two parts together, you’ll have some load in the circuit, rather than just a dead short. Secondly, the resistance of the circuit will probably be too low without them. If the bath looks like it’s boiling when you connect up the leads, you definitely need some additional load. In my setup, I have three 100W lamps in parallel in the circuit. Recalling that:
Wattage = Voltage * Current
The resulting current through each 100W bulb is:
Current = 100W / 120V = .833A
Since:
Voltage = Current * Resistance
The resulting resistance of each bulb is:
Resistance = 120V / .833A = 144Ω
Recalling that parallel resistance is governed by the equation:
The resulting resistance is:
Req = 1 /( 3/144Ω) = 48Ω
At that resistance and 12V, the resulting current would be .25A, or 3W, so if you wanted to use a 5W, 50Ω resistor, or better yet two 5W, 100Ω resistors in parallel, that would work fine.
Go to Section:
- Part I: Prologue
- Part II: Preparing the Plate
- Part III: The Etching Equipment
- Part IV: The Etching Process and Final Remarks
- View All
September 13th, 2010 at 3:09 pm
this is one of the coolest thing i ever seen i tryed it with brass plate it didnt work out as well as yours. but it was only a test . but thanks very much for the post
September 13th, 2010 at 5:45 pm
Thanks, Joe!
My understanding is that brass typically uses an acid etch, so you might try adding some vinegar (acetic acid) to the mix, and see if that improves the etch? The zinc plates are available at any good arts supply store, so there’s an option if you’d rather go to that way.
Again, just my understanding here, but I think brass emits considerably more hydrogen gas when you etch, so make sure you work in a well-ventilated space!
Post back if you have any success.
September 30th, 2010 at 12:04 pm
Actually I think the resistance of the hot light bulb tungsten electrode is higher than when it is cold. And as the filament boils off (slowly, but that’s how the insides of vacuum tubes and car light bulbs get shiny gray) the resistance will go up. Turns out you can predict bulb failure that way. That was almost-a-patent years ago. But I digress. Some Day I will measure some AC bulb resistances on and off to really prove this to myself. Thanks for the fun post… makes me want to go play with some chemicals.
October 1st, 2010 at 9:29 pm
Hey Bruce,
The resistance of a standard metal does increase with temperature, due to increased number of atomic collisions at higher temperatures:
http://en.wikipedia.org/wiki/Electrical_resistance#Temperature_dependence
As a practical matter, if you put an Ohmmeter on a cold bulb, you’ll measure a much lower resistance than the derived value that you would get from measuring current and voltage under load. Something to keep in mind if you’re using incandescent lamps as resistors. Glad you enjoyed the post, thanks for commenting!
April 4th, 2011 at 4:22 pm
Wow … that is really nice deep bite. Just wanted to say there is an easier way to etch zinc, mild steel and aluminum which does NOT need electricity because it is electro-chemical in nature and apparently non-toxic … hmmmm … maybe no gass-off!!!??? Check it out: http://www.nontoxicprint.com/etchzincsteelaluminum.htm