Resists for etching Aluminium with NaOH

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Discussion Overview

The discussion revolves around finding effective and affordable resist materials for etching holes in 0.3mm Aluminium sheets using a combination of a diode laser cutter and Sodium Hydroxide (NaOH). Participants explore various resist options and their effectiveness in withstanding the chemical process involved in etching.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant is seeking a low-cost resist for etching Aluminium with NaOH, listing several materials tested, including enamel paint, acrylic paint, Sharpie ink, vinyl masks, bitumen-based paint, and others.
  • Some participants suggest alternative resist materials, such as paint intended for high pH surfaces, which may withstand the NaOH better than those previously tested.
  • Concerns are raised about the effectiveness and availability of certain resists, particularly the two-part epoxy paint, which is noted as potentially the best option but difficult to source in small quantities.
  • Another participant questions the necessity of using chemical means for etching, suggesting that physical methods could be simpler for the thickness of Aluminium being used.

Areas of Agreement / Disagreement

Participants have differing opinions on the best resist materials to use, and there is no consensus on a single effective solution. The discussion remains unresolved regarding the optimal approach for etching the Aluminium.

Contextual Notes

Participants have not fully explored the limitations of each resist material, and there may be dependencies on specific conditions such as the exact concentration of NaOH and the method of application.

CWatters
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I'm trying to find a cheap DIY method to etch holes of various shapes through 0.3mm Aluminium sheet using 5-10% Sodium Hydroxide. The idea is to apply a resist to the Aluminium then selectively ablate it off using a diode laser cutter and then dissolve away the Aluminium using Sodium Hydroxide. By cheap I mean resists costing say £20 in small quantities.

The Internet has suggested various resists to try including...

Enamel paint (only survived seconds in the NaOH!)
Acrylic paint (only survived a short time in the NaOH)
Sharpie ink (too hard to remove it all with the laser)
Vinyl masks (adhesive dissolved by the NaOH allowing mask to come off)
Bitumen based paint (Best yet but finally came off before all the Aluminium was dissolved)
Nail varnish (not tried yet)
2 part Epoxy Paint (not tried yet)
Kapton tape with Acrylic adhesive (not sourced yet)

I also need to remove the resist using a solvent of some sort (Acetone, IPA, gasoline etc) although I suppose I could also laser it off.

So can any chemists suggest other resists or which to try next?

The 2 part Epoxy Paint is probably my best bet but it's not very convenient and hard to find in small quantities. 1K Epoxy paint in a can apparently isn't good enough.

Any suggestions?
 
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I am not a chemist, but if it was my project I would try a paint intended for high pH surfaces (such as masonry).
Such a coating might be hard on the aluminum, but I would hope that it lasts long enough for the NaOH and wash. I would think it would survive the NaOH itself without a problem.

As an example: https://www.millerpaint.com/product/ph-surfacer-interior-exterior-primer-2/
 
Thanks Scott, great suggestion.
 
Why are you resorting to chemical means rather than simply poking holes? 0.3 mm is just aluminium foil?
 

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