## Electro-etch ### Copper Nitrate ![[434775736_1277935226496178_3698101233151727939_n.jpg]] For a long time I used ferric chloride. It works super well. I didn't like the waste or the ongoing cost. Additionally, ferric chloride kept destroying my resists. I know I needed to find new resists anyway (see [[Resist Experiments]]), but I heard that electro etching with copper nitrate uses an essentially infinite solution and super clean etch lines. #### Experiment The first test with vinyl and copper nitrate solution was a 1.75" Golden Dolphin with vinyl resist. I started at 0.5A for the etch and increased it to 1A after 30min. I let it go for a total of 5 hours (I think) and I ended up destroying it. It undercut really badly and the hot glue I used on the side wasn't secure. Oops. ![[433182806_1160300051800641_1973956055508945182_n.jpg]] Next I am testing a 2" nickel silver disk with [[Pelican and Laurel Medallion|Lanea's Design]] on it. I'm keeping it at 0.5A for the entire duration. After four hours it seems to be looking really good. It etched unevenly though. On one side, the etch is a little over 0.5mm deep, but on the other it seems to be somewhere between 0.2-0.3mm. In [Relief Electro-etching for Champleve Enameling](https://guildofenamellers.org/index.php/component/phocadownload/category/39-docslinkedfromarticles?download=4:relief-electro-etching), RL Jackson shows that the center portion of the etched piece etches at a slower rate than the outside portions, which might make what I'm seeing here make sense. However, I expected the depth to be mostly uniform in a circle, but it seems tilted to one side or the other. My sponge did have some trouble floating directly parallel with the plate, though. This might account for some of the cause as well. Additionally, my cathode piece is a large bus bar connected to a circle, so some of one side might have etched at a greater rate due to its presence. In any case, on my next etch I'm going to wrap the bar part of my cathode with something so that only the circular part is exposed. I'm also going to switch up how I attach the disc and wire to the sponge so hopefully I can distribute the weight better. For my next experiment, I used the double sided carpet tape that I use for ferric chloride to attach the disk to the sponge. I ran a 24ga enamel wire through the back and stuck it to the tape as well. This allowed me to make a very solid electrical connection. Next, I sealed the edges with melted beeswax rather than the hot glue. It was far less messy and easier to cover what I needed efficiently. The wax held up well in the copper nitrate bath. The other new aspect I introduced was a magnetic stir plate. I was hoping that this would maybe aid the removal of debris from the surface of the disk and assist in evening out the etch depth. It didn't seem to cause a substantial impact to the end result. Etch details: - Started April 17, 2024 at 2.44p, ended at 11:02pm - Just over 8hrs. - Vinyl resist, carpet tape, beeswax - 0.5A - End depth (rough numbers here): - 0.6mm at the edges, 0.3mm in the center Ultimately this was the best etch yet with this set up. However, I'm still not very happy with it. My goal is to get an even etch of about 0.5mm throughout (or pretty close), but the variation of depth that I see might be a problem. I haven't enameled on these test pieces yet to determine whether this uneven depth is a problem, however, so it might not be that bad. Different colors fare better when they're thin than others. One suggestion I saw was that if a more even depth is needed, the piece can be removed when the outer edges are etched to an appropriate depth, applying extra resist to those areas, and etching again until the remainder achieves a satisfactory depth. The alternative is to etch until a sufficient depth is achieved throughout the entire disk. However, considering that some of the detail in my experiments is lost, I worry that etching further might be disastrous. I'm happy with the overall set up, though I might try using ferric chloride with vinyl resist and the magnetic stir plate. Those two aspects might make a substantial improvement on the etch but might also be more even than electro etching. ![[438065180_1847408652362303_7641512064114430100_n.jpg]] ### Salt Water Etch Several years ago, a good friend and I did some etching experiments and attempted a salt water etch. There might be a better way to do the salt water etch, but we didn't have a good time with it. I've also heard that unlike [[#Copper Nitrate]], it doesn't maintain well and potentially releases poisonous gases. It apparently dirties fast and ends up producing a lot of waste - just what I'd like to avoid with electro etching. I'd just go back to Ferric Chloride. #### Experiment Pictures ![[etch1.jpeg]] ![[etch2.jpeg]] ![[etch3.jpeg]] ![[etch4.jpeg]] ![[etch5.jpg]]