Screen printing a Radio Front Panel

How I went about screen printing text onto a vintage radio receiver
I have been restoring a Marconi CR100 Receiver. The CR100 was used by the British Navy (as the B28) and some Commonwealth Countries during WW2. The RAF also used it where it was designated as the R1297.
B28 Receiver
Mine came with a very rough front panel and as others may be interested in either restoring equipment panels or making panels for home brew projects, I describe below how I went about restoring the panel markings. It turned out to be (I think) a good result, was easier to do than I expected and the technique may be quite useful when making professional looking panels for homebrew projects.
The front panel had a number of dings and chips and was quite marked and faded. The original painted markings were very faint and in some cases nearly rubbed off entirely.
The Original Panel You can just see the original markings on the panel. The original markings were white paint. (click for full size image)
I initially thought I might be able to paint the markings back on by hand and as an experiment I tried using a 'liquid paper' pen. I overestimated my handwriting skills - the results looked pretty bad. (The images here were obtained by scanning the panel in a flatbed scanner - these ultimately were used to make a screen printing stencil).
left hand view of scanned panel
right hand view of scanned panel
I wondered about the possibility of making some sort of decal as I understand these can be printed using a laser or inkjet printer. The panel writing though is white and printers don't print white so this seems not a viable option (plus wouldn't really look original).
How did they originally mark the panel? - surely they weren't hand painted on every radio (and if they were the person who did the painting was very very good!).
I assume they must have screen printed the lettering so wondered if I could do the same...
I went to an artist supplies shop in Sydney and asked about screen printing and promptly walked out several minutes later clutching: (Yes - the salesman was pretty good!)
I assembled the frame, stapled the screen material to it (and then dropped it, it fell across a metal case, tearing the screen, so revisited the art supply shop, bought more material and remade the screen) and then went about preparing the stencil.
I scanned the panel using a flat bed scanner and then proceeded to edit the images using an image editor (I used Gimp) and added the appropriate text labels over the top of my liquid paper attempts.
part of printed transparency
I then reversed the image and blew the contrast up to get a black and white image of black text on a clear background.
I then printed this onto overhead transparency sheets (make sure you use ones designed for use in a laser or inkjet printer depending on what you use!). The panel required 2 transparency sheets as it is quite big so I joined them together with masking tape around the outside
final printed transparency
Next step I coated the screen with the photo emulsion and let it dry. (Made a mistake here - I used way too much emulsion and when it dried it had lots of blobs/drips where the emulsion was not actually dry). I then placed the transparency on the screen and exposed it under a floodlight for about 15 minutes. I then used a hose with a spray nozzle to wash away the unexposed emulsion. In this case the blobs were not dry and washed away as well leaving a stencil with a large number of big 'bubbles' all over it. All very artistic but not very useful. The lettering though, where it did appear, was good enough to encourage me to try again.
This time I used a much smaller amount of emulsion, redid the exposure and washed out the unexposed bits and got the screen below:
screen with exposed template
I had by now stripped and straightened the panel and repainted it (the local hardware shop colour matched the old paint on the panel by using a section of good paint that had been covered with a screwed on label).
I put the panel under the screen, squeezed a line of paint at one end of the screen, used the paint smearing thingy to wipe the paint across the screen and presto! - I got the result below:
printed panel view 1 (Click for full size images) printed panel view 2
As a final step I sprayed the panel with some clear varnish.

The End Result

front view of completed panel on the radio
detail view of completed panel on the radio
Things I learnt that may help: Good Luck!
Jonathan Kelly VK2JHK
jonk @ jonkster.com