Introduction to restoration
I find restoring old/degraded telephones to be an enjoyable and somewhat therapeutic activity. The following links provide an introduction to some of the restoration processes you will come across.
I wish to thank and acknowledge Mr R. Freshwater for his excellent website www.britishtelephones.com/.
This page discusses a range of restoration techniques:
This page covers cleaning and polishing of bakelite telephone cases:
I have one reservation regarding the advice offered on cleaning Bakelite by soaking overnight in water and detergent. If the surface is compromised (e.g. rough, pitted or discoloured) it is possible water can soak through into the underlying filler, expand it and further damage the case.
ABS plastic (added 22 Sep 2019)
Acrylonitrile Butadiene Styrene (ABS) is modern (mid 20th c.), usually opaque, thermoplastic. ABS first appeared in Australian telephones in the early 1960s with the introduction of 800 series 'phones and its use has continued into the 21st c, particularly in the cases of the larger, plastic, corded and cordless telephones.
Early ABS telephones are becoming collectors items. One issue with them is degradation and discolouring of the plastic's surface following long term exposure to direct sunlight, usually developing an unattractive brown hue.
In the past, the only solution was aggressive sanding and re-polishing to remove the degraded surface but in recent years new methods have been developed. One is the "Retrobrite" process http://www.retr0bright.com/
To quote Sam Hallas (http://www.samhallas.co.uk/collection/retr0bright.htm) "in summary, a group of vintage computer enthusiasts have developed a means of reversing the fading in ABS plastic caused by exposure to daylight. They state that the cause is a reaction of the the bromine-based flame retardant. The technique uses a commonly available domestic oxygen bleach powder to catalyse a reaction with hydrogen peroxide under the influence of ultra-violet light. The active ingredient in the bleach is a substance called TAED, (tetra acetyl ethylene diamine)."
Further review by Sam came up with a variation of retr0brite:"Anthony Pleticos has written from Sydney, Australia, to say that he has found an alternative means of bleaching plastic cases using hair salon crème developer. It's normally used in conjunction with hair dye to re-colour hair. He used the 20-volume (6%) version. The listed ingredients are: Deionized water, Hydrogen Peroxide, Cetearyl Alcohol, Sodium Lauryl Sulphate, Phosphoric Acid, Ethanol, Methylparaben. I need hardly add that with those ingredients you should wear old clothes, hand protection and optionally safety glasses when using this stuff. Anthony says he smeared it generously over the plastic and left the item in sunshine for several hours, repeating as necessary. He has had success with grey, ivory and mustard yellow telephone cases. Anthony has added, "I have also successfully applied hair crème containing hydrogen peroxide to reduce discolouration in Bakelite/Catalin as well as ABS plastics. Assuming safety precautions were taken, I applied the hair crème on an ivory Bakelite/catalin BT20/4 terminal box. In conclusion, discolouration can be significantly reduced in Bakelite/Catalin as well as ABS."
Yet another method: From "Andy's Shed" series https://www.youtube.com/watch?v=0RCxChcycd4
This method uses acetone solutions on a rag to dissolve and then rub away the degraded ABS surface. It is followed up with an abrasive automotive polish. in effect, a slightly less brutal version of surface sanding mentioned above. I experimented with the process and found (for me anyway) that initial application of pure acetone was too aggressive and difficult to control but when I diluted the acetone with methylated spirits (25% metho) it slowed down the evaporation of the solution and was easier to get a good result, albeit it took a little longer than shown in Andy's video.
As learnt above, acetone dissolves ABS plastic. This allows it to be used as an effective ABS glue. I've had success re-gluing broken telephone cases by liberally applying acetone with a cotton bud or similar to both edges and then pushing and holding them together until set. The trick is to leave the joint alone (at least overnight) to allow it to harden properly. Later, any raised glue lines can be sanded out and re-polished to give an unobtrusive result.
In addition, a "slurry" of ABS glue/filler can be made with scraps of ABS dissolved in acetone in a sealed (glass) jar. It takes a while to dissolve fully but will remain liquid if kept sealed and occasionally refreshed with acetone. Paint the slurry over the inside of a repaired surface to build up a strengthening layer. Similarly, it can be used as a filler. Since the acetone dissolves ABS, the glue bond is ultimately quite strong.
A typical restoration (added 9 Feb. 2015)
The following images are of a restoration I undertook for "Woodloes", a local community museum in late 2014. The phone was originally a 1920s "British Ericsson" that had some non-standard modifications done to it, probably around WW2. The original transmitter and receiver were replaced with a Bakelite 164 handpiece and the transmitter holes covered with a plate. It doesn't look like a PMG refurbishment which lends support to the museum's belief that it was either a local Railways or a privately owned telephone. The woodwork was cracked, the note tray was missing, the handset was grimy and paint splattered and the whole unit had suffered an ignominious coat of mission brown paint.
Note: I've had a surprising number of enquiries about removing the crank handle from these and earlier Ericsson phones (the front cannot be opened until it is removed). The handle is simply threaded onto the generator shaft. Normal clockwise operation retains the handle's tightness on the shaft. To remove, rapidly rotate the handle anti-clockwise. If it is not corroded it should come off easily. If it's a bit stiff, a trick to "brake" the generator is to apply a short circuit across the line terminals (if accessible).
The process was as follows:
- A series of photographs were taken before starting as memory aids and to enable a before/after record.
- All external parts were removed and carefully stored.
- The mission brown paint proved difficult to remove by gentler means so was ultimately removed with paint stripper and then the case thoroughly wiped down with damp rags to remove any traces of the stripper.
- The case was then wiped down with methylated spirits to even out/remove the original shellac coating that remained in places.
- Cracks were patched with wood filler and colour matched and the whole case very lightly sanded with the aim of preserving as much of the original timber surface as possible.
- The case was given several coats of brushed shellac with a very light sanding between coats. This used the same mixture as French polish, but as the original units were probably brushed or sprayed, rather than polished, I tried to keep it as authentic as possible.
- A replacement writing shelf was purchased from an enthusiast in New Zealand who made excellent replica parts.
- The shelf was stained with spirit stain to (reasonably closely) match the original timber and then shellacked like the case. It was then fitted using slotted wood screws. Remember, the ubiquitous Phillips Head screw wasn't invented until the mid-1930s and didn't commonly appear in telephones until the 1970s. Purists don't like Phillips Head screws much!
- The handset was next. Bakelite parts were washed down with 0000 grade steel wool soaked in methylated spirit. This removed the grime and paint splatter with minimal effect on the surface. The handset was given a quick hand buff with "Greygate polishing paste No. 5", restoring the surface nicely.
- Bell gongs etc. were painted with a spraycan of satin (not matt) finish black. This finish closely matches the original appearance of the parts.
- Finally assembled, the phone was delivered to the museum and was on display as a bit of local history when it re-opened for the new season in 2015.