Screen printing a Radio Front Panel
How I went about screen printing text onto a vintage radio
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.
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.
You can just see the original markings on the panel.
The original markings were white paint. (click for full
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).
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
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:
some screen material
some mitred wooden battens to make a frame
some light sensitive screen printing emulsion (Speedball
Diazo Photo Emulsion)
a thingy for smearing the paint
some acrylic white paint
(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
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
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
This time I used a much smaller amount of emulsion, redid the
exposure and washed out the unexposed bits and got the screen
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
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:
(Click for full size
As a final step I sprayed the panel with some clear varnish.
Things I learnt that may help:
- Don't use too much photo emulsion when painting the screen
- Don't drop your screen against anything sharp!
- During the printing phase, make sure you get an even spread of
paint before smearing it (or do 2 swipes) otherwise some of the
lettering in some places may be faint. I had to redo the first swipe
and this meant laying the screen exactly back where I put it originally
- I had made a simple hinged frame so it worked in this case (very
minor fuzziness on some letters near the bandpass switch but still
looks pretty good but I probably should have wiped the panel of paint
and redone it again to get a 'perfect' result)
- It was easier than I thought and the result with a bit of practice
will potentially look very very slick!