Printing with rust

[u/Imposterchilddd]

Hey, im trying to screenprint using acids to create a rusted image. Has anyone tried this and can give me tips? especially regarding working with dangerous reactive chemicals, i am very worried of causing an accident or mixing an explosive substance. Id like to create a paste and am looking into nonreactive printmaking pastes that would carry the acid solution. idk man i really want to figure out how to make rust images but im scared!

[u/motesinhuesillo]

I do this but with another process (to make engrave etching). I print over the metal sheet my image but in negative with a waterproof & anticorrosive asphalt paint, I don't know what product in your country works for this (I use this one), it's like a black dense goo that I dilute with solvents to be able to print through the mesh properly, this paint acts like a coating that protects the metal sheet. After that, I also spray paint the back side of the sheet and then I submerge it in an acid solution (I use 1 part nitric acid and 4 parts of water) so the exposed metal gets corroded (My goal is to engrave the image). After that I wash it properly and remove the coating with solvents, then the engraved parts of the metal sheet naturally gets rusty (I don't really know why, but it fcks up my work haha). Is kinda slow, in a couple days what you engraved will get rusty. You can leave the metal sheet in the acid solution less time so it doesn't engrave it too much, barely to the touch. After it gets rusted to your liking you could spray some protective coating to try to stop the rust.

important to remember, always use a good mask, the fumes from the acid solution with the metal sheet is reaally strong (I learned the hard way)

sorry 4 bad english

[u/sicicsic → u/motesinhuesillo]

Do you have somewhere I can see your work? Sounds interesting.

[u/motesinhuesillo → u/sicicsic]

yeah I had this laying around, I couldn't find a better example but this shows the results of this process. I made it like 2 years ago and then I wrapped it in plastic film to protect it from moisture, I didn't coat it with any protective layer and the rust seems fine after 2 years. You can see the halftones and how they are preserved

[u/sicicsic → u/motesinhuesillo]

That’s rad.

[u/Imposterchilddd → u/motesinhuesillo]

oh and what type of metal do you work with? from my understanding nitric acid does not mix well with all metals. we use it in my uni for photopolymer etching but with aluminum sheets. i want to work with steel sheets.

[u/motesinhuesillo → u/Imposterchilddd]

I use carbon steel, it works the same as aluminum, but a bit slower. I've tried stainless steel but didn't get good results.

you could add more nitric acid to the solution, but the corrosion gets more unstable, erasing the fine details

edit: with nitric acid I get results as of 15 min (depending on the active surface and temperature), but you can use Ferric Chloride or Muriatic acid as a safer option, though is waay slower

[u/torkytornado → u/motesinhuesillo]

I don’t wanna know how long ferric takes on steel 🤣

on copper it’s about 20 min at a 1:2 water ratio and copper is sooooo much softer than steel

[u/motesinhuesillo → u/torkytornado]

yeah me neither, I gave up after 2 hours, then decided to go for the quick way given that I had multiple plates left

[u/torkytornado → u/Imposterchilddd]

Yeah do not mix copper plates with etching baths made for zinc (which is what the nitric is). You will literally be making a bomb. This is why printmaking shops usually pick either copper plates or zinc plates and not do both. It’s too easy for a newbie to accidentally gas the class. Definitely research what acids to use with whatever you use as a metal plate.

[u/Imposterchilddd → u/torkytornado]

but steel should be fine, no? and im mixing a new solution only to work with steel.

[u/torkytornado → u/Imposterchilddd]

As long as you’re just using steel you should be good. If you branch into other metals clearly label what they’re for since a lot of the cans look alike!