EVEN MORE Retrobright Experiements - Restoring an Ivory GPO 746 Telephone

I've been doing some experiments with Retrobright recently, a process which uses Hydrogen Peroxide to bleach plastic back to it's original colour. Firstly I experimented with how temperature and concentration affected the bleaching process (link), and once that was complete I experimented with how time affects the process (link). I didn't make any groundbreaking discoveries but I've settled on using 3% H2O2 at 40°C without any laundry oxidizer going forward.

As I still had the equipment out and surplus H2O2 I thought I'd bleach an entire phone. I've bleached phones before but I'm terrible at taking before / after photos but this time I remembered, just - you'll notice the before picture is missing the handset cord because I forgot to take a photo before starting to strip it. Doh!

I picked this phone up along with another for a grand total of £5. I intended to strip it for spares but as it turned out to be an "8746" (It already has the required mods to work on a modern line) I thought I'd keep it intact. Here it is pre-bleaching. It's very, very yellow.



More Retrobright experiments

I recently did some experiments with Retrobrighting plastics, using Hydrogen Peroxide to bleach them back to their original colour. I wanted to see how temperature and concentration affected the process. Once I'd gathered the results I wanted to run another experiment to see the affect of time.


Retrobright Experiments

Retrobright, also known as Retr0bright is a process of bleaching sun damaged ABS plastic back to the original colour using a solution of Hydrogen Peroxide and laundry oxidixer containing TAED. It was originally developed for restoring retro computers which left the factory an off-white / light beige colour and often went yellow or even brown with age.

As you may know I've started collecting / restoring old telephones and the ABS plastic the GPO used to make phones in the 60s onwards also suffered from the same yellowing issue. It's most obvious on the Ivory models (Frequently sold incorrectly as "Yellow") but also affects the appearance of the coloured models, most notably the green and grey versions.

I've retrobrighted a couple using UV light, but in the UK the sun is variable and almost non-existant in winter, so I thought I'd try using heat instead of UV, and do some testing with different concentrations, temperatures, and amounts of oxidizer.