Photo Etch - Seeking Help for Project

[Ray Allred]

Hi all,

Foremost, I'm not a photographer, but am a bit stuck trying to figure something out and thought you kind and knowledgeable folks could help me figure this out as I do believe you guys might know the technique. I hope I'm in the right place and a post like this is allowed. Forgive me if not.

Years ago, a fellow shared with me a procedure to making photo etched cockpit instrument panels (picture attached). I was interested in building some panels for a home simulator, but life got in the way, now I'm looking to do this again. Although I have a co2 laser that can engrave the lettering, the results are not very good as I have no depth control.

To give you a little insight as to how it works: The panels are made out of clear sheet acrylic, then a very thin sheet of white styrene is laid on top of it (or acrylic is painted white). It's then painted gray (cockpit color). The gray paint is then removed either by laser or a chemical etching process, exposing the white underneath (white lettering). Since white is a translucent color, it allows the panel to be backlit.

I made a spreadsheet of the process (attached), but I don't quite understand how it all works. The artwork (lettering) is printed on a transparency sheet and laid on top of the painted panel, then exposed under a UV light for 3 minutes, which from what I understand, hardens the gelatin emulsion in all the areas there is no artwork (printed in black, protecting emulsion coat). One then removes the transparency, and with a spray gun (used for painting) spray acetone which dissolves the emulsion along with paint in the areas where there was artwork (lettering). In other words, the black letters printed on the transparency protected those areas from the UV light.

The guy who shared this with me said it's called a "chemical etching" process, but not only do I not have a way of contacting him any more, I'm confused as to what a process like this is called and how all the chemicals interact with each other, so, I'm reaching out to you guys who perhaps would know what's going on here and how this works as I've heard you guys often work with etching and UV exposure.

I'm able to find all the chemicals in the attached procedure spreadsheet, except "lipal". The gentleman told me this served as a lubricant. Again, not sure if this could be substituted with something else (?).

Finally, thank you very much in advance for reading this and I sure do hope someone out there can help me better understand how this process works.

Kind regards,

Ray A.

View attachment 269553

 

[koraks]

Your process has some similarity with pcb etching, which is something I do a lot of. The main difference is that I etch copper instead of a polymer, but the masking process if conceptually similar. I might be able to help you a bit.
My first suggestion would be to forego the gelatin process as its unnecessarily difficult and the use of dichromate is also an unnecessary health and environmental risk. I would suggest using a photo polymer instead. This stuff comes in many forms, such as a film that you can laminate, a thick paste that you can roll or smear onto the surface or a spray (usually this is a positive resist instead of a negative). I personally use the film and the paste, mostly the paste though. It develops in sodium carbonate solution, which is easy to make with household materials (I.e. washing soda). No dichromate, lipal or gelatin are needed. Apply the resist, dry it if it's the paste, then overlay the artwork and expose using UV (sunlight will also work but is evidently difficult to control). Then develop the resist with sodium carbonate, harden the resist some more with additional UV exposure, and "etch" your material with acetone. Finally remove the resist by soaking in a sodium hydroxide solution (10% or so, it's not critical).
I can go into more detail if you like; just let me know what you need to know.

Btw I'll report your post to have it moved to the "alternative process" section as the chemistry/methods involved in your process have similarities with some of the alternative printing processes some of us use. You may get some more useful responses this way.

 

[bernard_L]

Sounds complicated. 15 years ago, had a similar need for work; subcontracted for a reasonable price (not my money, though). Process goes roughly like this:
Aluminium plate. Anodize to one of the available colors. Then laser etch to expose the bare aluminum. Optionally, re-anodize (and color?) the etched parts.

 

[koraks]

Anodize to one of the available colors. Then laser etch to expose the bare aluminum. Optionally, re-anodize (and color?) the etched parts.

But that doesn't result in translucent artwork that can be backlit, which is what OP seems to need.
Of course it can still be contracted out, but then again, I take this is a DIY question.

 

[AgX]

The intended process reminds me of Polymer Resist.
In any case the intended coating must act in its final stage as a conventional varnish. And here I see proplems.

 

[koraks]

In any case the intended coating must act in its final stage as a conventional varnish.

Not sure what you mean, but as I understand it, the final product will consist of an acrylate substrate with a grey paint on top of it that is selectively etched with the artwork. An additional transparent varnish could be applied on top of this at the end for additional protection, but this was not included in the original process description. I do think it would be a good idea though.

 

[AgX]

A substance that is soluable and lightsensitively hardened (or even the other way round) is not necessarily apt as permanent coating.

 

[koraks]

A substance that is soluable and lightsensitively hardened (or even the other way round) is not necessarily apt as permanent coating.

In the concept proposed here there is no photo-hardened substance that is part of the final assembly.

Besides, solder mask on pcb's is also a UV curing ink that is specifically intended to be long term stable, mechanically tough and very permanent.

 

[AgX]

Solder masks are silk screen and not optically printed.

In the concept proposed here there is no photo-hardened substance that is part of the final assembly.

If so, then please explain.

Furthermore, this is a photoechnical forum. I thus expect that any process inquired on is a photographic one.

 

[koraks]

Solder masks are silk screen and not optically printed.

Solder masks certainly are.

If so, then please explain.

The process OP suggested, although it is incomplete in its description, is fairly straightforward conceptually. The gelatin emulsion is applied as a mask, which is then exposed through transparent artwork. The mask is selectively washed away (this part is missing from the Excel screencap), after which the underlying paint layer is dissolved selectively using acetone. After this, the remaining gelatin mask may be removed, although it can also be left in place, although it does not serve a distinct function at this stage anymore.
Your earlier remark can be turned into the recommendation of applying a varnish/topcoat for additional sealing/protection, which I think is a useful recommendation.

Furthermore, this is a photoechnical forum. I thus expect that any process inquired on is a photographic one.

It's a photographic process, just not for pictorial purposes. If I and/or others feel like thinking about this, I don't see anything wrong with this. Feel free to abstain from participating.

 

[AgX]

I see, we got a light-hardened gelatin coating acting only as resist.

I do not see why you are agressive to me.
Your wording on that photgraphic thing was ambiguous. I did not realize that your emphasis was on the end of your sentence. I could not see that process formular when I replied, as my browser did not make it appear.

 

[koraks]

My apologies, I did not intend to be aggressive. Hopefully I have been able to clarify the process the way I understand it. Granted, the OP misses a few important details; you put your finger on one of them.

 

[Ray Allred]

Your process has some similarity with pcb etching, which is something I do a lot of. The main difference is that I etch copper instead of a polymer, but the masking process if conceptually similar. I might be able to help you a bit.
My first suggestion would be to forego the gelatin process as its unnecessarily difficult and the use of dichromate is also an unnecessary health and environmental risk. I would suggest using a photo polymer instead. This stuff comes in many forms, such as a film that you can laminate, a thick paste that you can roll or smear onto the surface or a spray (usually this is a positive resist instead of a negative). I personally use the film and the paste, mostly the paste though. It develops in sodium carbonate solution, which is easy to make with household materials (I.e. washing soda). No dichromate, lipal or gelatin are needed. Apply the resist, dry it if it's the paste, then overlay the artwork and expose using UV (sunlight will also work but is evidently difficult to control). Then develop the resist with sodium carbonate, harden the resist some more with additional UV exposure, and "etch" your material with acetone. Finally remove the resist by soaking in a sodium hydroxide solution (10% or so, it's not critical).
I can go into more detail if you like; just let me know what you need to know.

Btw I'll report your post to have it moved to the "alternative process" section as the chemistry/methods involved in your process have similarities with some of the alternative printing processes some of us use. You may get some more useful responses this way.

Hello Koraks, thank you very much for your replies and wisdom! I certainly would like to learn more about the process and also where I could purchase the necessary materials. Is there any way we would PM?

 

[koraks]

Hi Ray, sure, feel free to message me. Sounds like a fun project, I'm sure I can give you some pointers.

 

[MattKing]

Hi Ray, sure, feel free to message me. Sounds like a fun project, I'm sure I can give you some pointers.

He probably can't message you, because of his low post count and the new anti-scam messaging restrictions. But if you message him, he can participate in a "Conversation"

 

[Ray Allred]

He probably can't message you, because of his low post count and the new anti-scam messaging restrictions. But if you message him, he can participate in a "Conversation"

Hi Matt, thanks. Koraks did just that. Thanks to all who have chimed in, your input is greatly valued!

-Ray

 

[koraks]

In case anyone is wondering what happened on this front - I've been in touch with Ray intensively over the past few days and he's currently using UV curable film to get the artwork onto his workpiece. Results so far are very encouraging indeed and I'm quite convinced he'll get the job done. He's using a workflow that is very similar to how I went about doing photopolymer intaglio work when I was still into that.