Might I suggest using a commercial product first (to verify one part of the process using known commercial materials) then move to making your own photoresist? <
http://www.vetco.net/catalog/product_info.php?products_id=937> is one example; I'm sure Digikey carries something like it. Many years ago, silkscreen photoresists were made with Elmer's Glue and some additive that I can't for the life of me remember. That would be what I would search for. (The sensitiser was a chromate or bi-chromate, I think.)
HTH,
Donald.
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----- Original Message -----
> From: "Rick Sparber" <rgsparber@...>
> To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
> Sent: Friday, March 22, 2013 8:25:15 AM
> Subject: RE: [Homebrew_PCBs] Re: etching the OD of a cylinder to create a graduated dial
> Harvey,
>
> Pantographs and lasers are all existing technologies. My hobby is to invent
> new things, especially things that are simple. So if I could apply some
> homemade mixture to the cylinder, do a contact print, and then etch, I would
> be happy.
>
> Rick
>
> -----Original Message-----
> From: Homebrew_PCBs@yahoogroups.com
> [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Harvey White
> Sent: Thursday, March 21, 2013 1:29 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] Re: etching the OD of a cylinder to
> create a
> graduated dial
>
> On Thu, 21 Mar 2013 11:18:29 -0700, you wrote:
>
> >Andrew,
> >
> >I know that photo etching has been done on flat plates so assumed it
> >could be made to work on a cylinder. I would wrap the artwork around
> >the cylinder and rotate it at a constant rate under the UV light. The
> >missing link here for me is an easy to apply photo resist. I've
> >always
> >used pre-treated circuit board material and had good results.
> >
> >One option I may pursue would be to coat the cylinder with wax and
> >then
> >use engraving techniques to scribe through only the wax. In this way,
> >mistakes can be fixed by reflowing the wax. Not sure how to do the
> >numbers. This method probably would work but is too much effort for
> >me.
> >If a spray-on photo resist could be made to work, that would be the
> >key.
>
> Try a pantograph and larger patterns to engrave the numbers. Another
> option
> would be Laser engraving. You need to rotate the cylinder and move
> perpendicularly to the axis. Same thing for normal engraving.
>
> Might be worth the effort.
>
> Harvey
>