I have been experimenting with copper in order to make durable memorial signs. I treat a polished piece of sheet copper (or thicker) just like a PCB: degrease, spray photoresist, expose with laser printer foil on it to UV lamp, develop in 0.8% NaOH solution, etch in concentrated FeCl3 solution. Etch hard and long, until fine details start to disappear. FeCl3 etches in depth five times faster than horizontally. Then rinse and put it in a very, very light solution of K2S (one little crystal in a few liters of water). This is potassium sulphide, called sulphur liver in German. It stinks and it's used for medical baths and may be bought in pharmacies. The solution must be just slightly yellow. This will turn the etched surface into insoluble, deep black copper sulphide CuS. The etching leaves a matte surface so the black will be accordingly dull. Agitate with soft brush. Higher concentrated K2S solution will cause the developing CuS to come off in thin layers, making an stainy, uneven colour distribution. As soon as the black color is reached (work with good lighting!), rinse, dry and remove photoresist. You have a shiny copper pattern on dull black background. This works also with brass and maybe (didn't try) with alpacca or some other silvery copper alloy to make good contrast.
Peter andy pugh schrieb: > On 8 January 2012 14:59, Joachim Franek <joachim.fra...@pibf.de> wrote: > > >> A temperature treatment of the lacquer >> at 190°C will result in durable inscriptions or graphics having a blackish- >> brown color >> > > It is worth remembering, though in my case I was much more concerned > about reflectivity than colour. A black/brown shiny layer would not > work. > > ------------------------------------------------------------------------------ Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex infrastructure or vast IT resources to deliver seamless, secure access to virtual desktops. With this all-in-one solution, easily deploy virtual desktops for less than the cost of PCs and save 60% on VDI infrastructure costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
