Etching with caustic soda - advice

lmorse · February 04, 2015, 02:03:50 AM

QuoteI plan on testing it a little more in my next build so I'll confirm then whether or not this works 100% but for now this looks the most promising for me.

Cool! Look forward to your results.

joeowens994 · February 12, 2015, 12:12:48 AM

Okay so I tried out the etch primer as a mask on an etch today. I taped the top of the pedal, sprayed the sides with the primer, and let it dry overnight. Then the next day I removed the tape, ironed on my design using toner transfer, and fixed any mistakes in the toner with some etch primer that I sprayed into a plastic cup and applied to the pedal with a toothpick. I didn't use tape whatsoever to mask the pedal, so it was all up the the etch primer and the toner. What I noticed was:

- The etch primer on the sides held firm, except for at the bottom edge of the pedal. My guess is that the caustic that had run down the sides of the pedal and had pooled up around the bottom edge was etching the bottom edge and removing the paint from the bottom up.
- The etch primer that I applied with the toothpick was etched off. I only let that part dry for a couple hours and without direct sunlight, so maybe with a longer dry time this might work better.

I'd like to try doing toner transfer first, then applying etch primer with a brush to everywhere else, then letting it dry overnight. I'll update again if I get a chance to try that method and let you know how it goes.

joeowens994 · June 18, 2015, 01:28:14 AM

I thought I'd bring this one up again because I've been experimenting with more methods of masking for my etches. While the etch primer did help a bit, I still found that the caustic could eat through it and etch where I thought I had masked.

I've finally settled on something, and I've tested it enough times to be sure that it totally masks off the caustic. Craft glue does the job perfectly.

What I do is I tape off everything that I want to mask, usually the sides of the enclosure and any large area covered in toner that I wouldn't be etching anyways. Then I apply the craft glue around the join where tape meets the enclosure. This way, the caustic can't get under the tape because the craft glue masks it. Then if there are any spots that the toner has not stuck, I put a small amount of glue over them. Wait until the craft glue dries (mine goes on white but dries clear), then etch away. I haven't had a problem since I started using it. Try it for yourself, I'd love to see if others get the same results as I do with it.

Pettol · June 20, 2015, 03:58:32 PM

Interesting! Looks like an alternative/complement to the enamel paint I'm using. What brand is that? (maybe it's the same thing even here in Sweden....)

joeowens994 · June 22, 2015, 02:05:34 AM

The brand is Selleys, but I'm sure most other craft glues would work too. Try some out and let me know how it goes for you! I'd like to try some other brands out for myself and see if it makes a difference.

tubegeek · June 23, 2015, 08:33:46 AM

Is "craft glue" stickier than "white glue"? The "white glue" most common in the US is Elmer's, it's used for sticking paper together and other low-strength tasks. One level up is something a bit gooier, not sure of the common brands.

PRR · June 24, 2015, 01:45:33 AM

> The "white glue" most common in the US is Elmer's

And Elmo's isn't just Elmo's any more.

Lately I see a lot of "School Glue" (both Elmer's and generic). It looks the same, maybe it can be washed out of clothes easier?

Carpenter's Yellow Glue is roughly the same stuff but a lot less likely to wash-off once fully set.

All of these will "stick" to clean metal, but pop-off easily. So they may be fine masks.

Hexjibber · December 21, 2015, 07:04:43 AM

Quote from: joeowens994 on June 18, 2015, 01:28:14 AM
I've finally settled on something, and I've tested it enough times to be sure that it totally masks off the caustic. Craft glue does the job perfectly.

Sorry for the old thread bump but just found this one, I am the author of the guide quoted at the beginning of the thread, hope it proved useful. There are so many variables it's hard to write something that will work for everyone but I have tried to be as concise as possible. I've since updated it with a few revisions based on the feedback on here and some other forums.

I should point out also that Pettol was the chap that helped me along when I wanted to try Caustic Soda for the first time, his advice was invaluable and his results speak for themselves!

I will definitely give the craft glue a try, thanks for the tip! I don't normally need to mask off any surface areas as am able to get a complete transfer 99% of the time but stopping the solution running down the sides of the box and under the tape would save me the job of sanding the sides down afterwards!

Hope you're enjoying etching!

Cheers,
Graham

joeowens994 · December 22, 2015, 06:00:28 PM

Quote from: Hexjibber on December 21, 2015, 07:04:43 AM
I will definitely give the craft glue a try, thanks for the tip! I don't normally need to mask off any surface areas as am able to get a complete transfer 99% of the time but stopping the solution running down the sides of the box and under the tape would save me the job of sanding the sides down afterwards!

Thanks Graham! Your guide has been a huge help to me and seeing some of your work pop up on tumblr was one of the reasons I wanted to start etching. Thanks for sharing it with everyone.

Hexjibber · December 23, 2015, 10:41:39 AM

Quote from: joeowens994 on December 22, 2015, 06:00:28 PM
Thanks Graham! Your guide has been a huge help to me and seeing some of your work pop up on tumblr was one of the reasons I wanted to start etching. Thanks for sharing it with everyone.

Pleased to hear it's been helpful, if you have any questions feel free to give me a shout!

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Etching with caustic soda - advice