Blackening Hard Rubber Receiver Casing?

[WEBellSystemChristian]

I have a hard rubber receiver shell for a 143-144 receiver that I'm using for a candlestick project. The shell had a fair amount of use in its life, and the original black has rubbed off over time, revealing the used brown color.

I was wondering if anyone has a tried-and-true method to bringing back the 'black' finish? Shoe polish? Wax?

It's not really bothering me, because the phone will be made up of several different parts to look like a black WE stick with a nickel transmitter, and it's difficult to avoid making it look 'too new'. The aged receiver helps make it look weathered, and more authentic.

So I have two options; either leave the receiver as-is, or make it look original in black with some sort of wax or grease.

[Ktownphoneco]

Unless you have something I've never seen before, what you will probably find, is that the receiver shell has discolored.      I'm not sure whether it's the ultra-violet rays from sun light, air itself, or some of the various gases that make up our air, or a combination of some or all of it.      But if you decide you'd like to get it back to it's original color, I'll explain the process, and there is some work involved.      The original "black" is under the brown, you just have to dig for it, or more correctly, "sand" for it.    Surprisingly enough, what's waiting under that brown is something I refer to as a "black pearl".   It's a very deep black, and extremely shiny if done correctly. 
If your interested, or anyone else, let me know and I'll type out the entire procedure, and take some pictures showing the before, and the after.

Jeff Lamb

[Sargeguy]

I would love to see a tutorial on the topic.  I have sanded them with mixed results.

[Ktownphoneco]

I'll run through the process, but I'll be away for 9 days so the pictures will have to wait until I get back.     The extent of discoloration will determine the grade of wet / dry sand paper to start with.  If the receiver in question appears brown enough that one would believe it was manufactured that way, then I would start with 18o grit.      I do all my sanding with water, using either a large plastic pail, or the laundry sink.    The only issue to be careful of are the threads on the outer circumference of the receiver shell.    I'm right handed, so for me, holding the receiver in the left hand with the mouth of the shell facing to my left, and using my right hand to hold the sand paper, allows me to control how close to the threads I get with the sand paper.
Assuming we're starting with 180 grit, sand the shell until you more or less reach the solid black color of the receiver shell.      At that point start reducing the grit number.     Typically I reduce as follows, 180 / 220 / 320 / 600 / 800 / 1500 / 2500.      The finer the grit you can start with the better insofar as how much work is needed to complete the sanding.
Once the final wet / dry grit of 2500 is used, the receiver shell is ready for buffing.       I use a cotton flannel buffing wheel with an 8 inch diameter.      I have a dual speed buffing motor and use a speed of around 1400 rpm.       I use a product called DICO PBC (Plastic Buffing Compound), which is made in Utica NY, and sold at a number of stores, of which Ace Hardware is one.
The result of the buffing process will produce a very shiny black pearl effect.     
That's it in a nut shell.     This process pertains mostly to the hard rubber type of receivers.     Other materials will produce different results, some of which will be acceptable, and others not so much.

Jeff Lamb

I'll respond to any questions during the course of the week when I have computer access.   

[dsk]

The Norwegian phones with hard rubber parts (typically smelly when you have held it in a warm hand for a few minutes) has been tough to cope with, my best result so far is just polishing with black shoe polish every second day until it looks well, then let it dry for some days before you put it near your skin, a black ring on the ear may look a little odd 

dsk

[DavePEI]

The Norwegian phones with hard rubber parts (typically smelly when you have held it in a warm hand for a few minutes) has been tough to cope with, my best result so far is just polishing with black shoe polish every second day until it looks well, then let it dry for some days before you put it near your skin, a black ring on the ear may look a little odd 

dsk

That reminds me of a joke we played many years ago on one of our supervisors at the P.O. He had a desk in the center of the floor, and a black 565 on it. He was known for taking long lunch hours, and one one occasion, one of the clerks snuck up and liberally applied black shoe polish to the receiver. When Buffy returned, one of them snuck over into the lettercarrier section, and called his phone. He picked up the phone, put it to his ear, and for the rest of the night, walked around with the blackest ear one could imagine! No one let on that anything was wrong. I can just imagine what he must have thought when he finally discovered it!

Getting away from the phone, we used to have a customs official right in our facility. His job was to inspect every suspicious parcel that came in. One day, a small box came in leaking a gray-white powder. He picked it up, and wetted his finger, touched the powder with it, and did a taste test. Only afterwards did he turn it over, and to his dismay, read the label which said the Cremains of Joseph XXXXXXXXXXXXXX. He left work immediately, and was found some hours later recovering in a local bar     

[twocvbloke]

Getting away from the phone, we used to have a customs official right in our facility. His job was to inspect every suspicious parcel that came in. One day, a small box came in leaking a gray-white powder. He picked it up, and wetted his finger, touched the powder with it, and did a taste test. Only afterwards did he turn it over, and to his dismay, read the label which said the Cremains of Joseph XXXXXXXXXXXXXX. He left work immediately, and was found some hours later recovering in a local bar     

Reminds me of this scene from the first episode of Red Dwarf (Titled "The End"):

https://youtu.be/6Hrwut2dV0k?t=2m36s

Everybody is dead Dave...

Shame they didn't leave the bit in where Holly reveals what the piles of powder are...

[Ktownphoneco]

On May 30th, 2015, I described the process I used for sanding and polishing "brown" hard rubber receivers.     Since I was leaving for Alberta that day, I didn't have the time that day to post an example (photos) of what the results of that procedure look like.        Attached is a "pdf" file showing a Western Electric type 122-W OST receiver, which was sanded and polished using the method I described.
This particular receiver was originally "brown" when I bought it, and it's turned into a bit of an experiment.      I'm trying to see if it stays in it's present polished state if it isn't exposed to light.      It's been sitting in a dark cupboard with very little exposure to natural light for 2 years now, and so far, it's remained exactly the same as the day I finished polishing it.
So I'm inclined to assume that the "brown" discoloration is due primarily to it's exposure to sun light.
N.B. - The receiver is empty at the present time.   The machine screw in the picture is just sitting there for looks.    There are also some white dust and lint specks in the pictures, but that's all they are.     Other than that, the polishing is flawless.

Jeff Lamb


   

[WEBellSystemChristian]

On May 30th, 2015, I described the process I used for sanding and polishing "brown" hard rubber receivers.     Since I was leaving for Alberta that day, I didn't have the time that day to post an example (photos) of what the results of that procedure look like.        Attached is a "pdf" file showing a Western Electric type 122-W OST receiver, which was sanded and polished using the method I described.
This particular receiver was originally "brown" when I bought it, and it's turned into a bit of an experiment.      I'm trying to see if it stays in it's present polished state if it isn't exposed to light.      It's been sitting in a dark cupboard with very little exposure to natural light for 2 years now, and so far, it's remained exactly the same as the day I finished polishing it.
So I'm inclined to assume that the "brown" discoloration is due primarily to it's exposure to sun light.
N.B. - The receiver is empty at the present time.   The machine screw in the picture is just sitting there for looks.    There are also some white dust and lint specks in the pictures, but that's all they are.     Other than that, the polishing is flawless.

Jeff Lamb


   

I'm guessing that the 'browning' is just a combination of wear and exposure to skin oils; sort of like how Bakelite gets textured after being used for so many years. The browning on my receiver is more obvious right where it hangs on the hook, and I don't think sunlight would be more exposed from behind a metal switchhook.

Just my two cents.

[unbeldi]

On May 30th, 2015, I described the process I used for sanding and polishing "brown" hard rubber receivers.     Since I was leaving for Alberta that day, I didn't have the time that day to post an example (photos) of what the results of that procedure look like.        Attached is a "pdf" file showing a Western Electric type 122-W OST receiver, which was sanded and polished using the method I described.
This particular receiver was originally "brown" when I bought it, and it's turned into a bit of an experiment.      I'm trying to see if it stays in it's present polished state if it isn't exposed to light.      It's been sitting in a dark cupboard with very little exposure to natural light for 2 years now, and so far, it's remained exactly the same as the day I finished polishing it.
So I'm inclined to assume that the "brown" discoloration is due primarily to it's exposure to sun light.
N.B. - The receiver is empty at the present time.   The machine screw in the picture is just sitting there for looks.    There are also some white dust and lint specks in the pictures, but that's all they are.     Other than that, the polishing is flawless.

Jeff Lamb

Astounding and outstanding result!

I had researched the degradation of vulcanized rubber at one time, when I had tried to clean the key knobs (handles?) of a cordless PBX I had acquired. At first I thought the knobs were some form of Bakelite. The knobs had various shades of black and dark brown and looked just dirty, and some where indeed just dirty with baked on dust and grime. I knew that Bakelite turns brown from the influence of moisture, forming a layer, or very often small pockets, of phenol alcohols, which can usually be easily removed with cleaners and solvents.  So I used a solvent on the knobs, but instead of removing the 'dirt' and turning pure black, they turned brown (see picture, bottom pair) to my surprise.  I tested the process an a bunch of the knobs, with the same result.

Finally, I wanted to know the actual color inside the bulk of the material, so I used a dremel took to grind away some material from the inside thread in a very small area, and it turned out to be black. As the material appeared much less brittle than Bakelite, I decided it was actually hard rubber (vulcanized rubber).

Apparently, the treatment resulted in a layer of brown material on the surface.   I considered polishing, but with several dozen small knobs this seemed just too laborious a process, and I was concerned it would destroy the textured surface of the knobs. Having shiny polished knobs on an old 1930s PBX was not the effect I wanted. I just wanted them to be clean. I ended up using a black spray paint on the brown knobs and tossed them in a tray made from paper to absorb any excessive paint and prevent smooth surfaces to yield an old look (top pair in the picture)—never mind the dust specs that are in the picture as well.

Anyhow, vulcanized rubber may degrade in many ways other than light, as you were testing for. In addition to light, it is effected by temperature, moisture, oxygen, or many other types of chemical attack, and simply aging.  In particular for a hand-held receiver, I would suspect the chemical reaction with moisture and sweat from a human's hand.  Damage from light is supposed to create a crazing effect often^{[citation needed]}.  The vulcanization of isoprene (rubber) typically involves curing with sulphur compounds, which forms —S_x— cross-links between the hydrocarbon chains, thus locking them in place, and hardening the material.

[Ktownphoneco]

I do agree with both of you;  skin oils, sweat (salt) will have an effect on the color of the finish.      However I think the ultra-violet rays of the sun have a greater effect over time.    I've just photographed 2 old 140 series receivers.  (attached)    (They remain in their respective left - right positions in all photos).         I had gone over the skin oils / sweat theory in my mind for some time, and I think slight variations in the rubber formula used at the factory when they were made, could create a situation where skin oils and sweat could have a greater or lesser degree of influence on the overall dis-coloration.         However when I examined some of these brown receivers carefully, I found that in some cases the discoloration is too even, and would be difficult achieve strictly from skin oils and sweat unless the individuals using the receiver, made a point of handling every inch of the receiver.         That didn't seem plausible.   
As can be seen on one receiver cap, the area facing down adjacent to the portion which would touch the ear, and which contains the maker's name and series number, is still relatively black.     Now, one could say, that's because it probably doesn't touch a persons ear.     Well that's true, but it probably touches hair, which is also fairly oily.       But it's also facing straight down towards the floor, which would most likely create less exposure to "UV" light.         One receiver shows a "feathered" patch of black where a receiver hook would rest against it, and it's more or less the same on the exact same spot where the other fork of the hook would be.

At any rate, that's my best theory to date.   

Jeff Lamb

[19and41]

There is a method I have used to blacken a relatively porous material.  The material should be able to be wetted with some 91% isopropyl alcohol.  I take a brand new black magic marker and paint the surface with it.  The marker leaves a glossy and uneven finish, but that isn't the desired result.  You then take a paper towel pad dampened with the alcohol and wipe down the applied marker.  It will dissolve the glossy coat and the black will be absorbed by the material, depending on the porosity. it acts as a staining agent on the material and you can apply more as needed.  Then you can use a polish to get the desired shine.  be sure to use a polish that will remain either transparent or is the color of your item.

[unbeldi]

There is a method I have used to blacken a relatively porous material.  The material should be able to be wetted with some 91% isopropyl alcohol.  I take a brand new black magic marker and paint the surface with it.  The marker leaves a glossy and uneven finish, but that isn't the desired result.  You then take a paper towel pad dampened with the alcohol and wipe down the applied marker.  It will dissolve the glossy coat and the black will be absorbed by the material, depending on the porosity. it acts as a staining agent on the material and you can apply more as needed.  Then you can use a polish to get the desired shine.  be sure to use a polish that will remain either transparent or is the color of your item.

I have the feeling that this effect is very similar in principle to my version of using spray paint (see pics earlier) and removing the excess liquid immediately by rolling them in my paper tray.

[19and41]

Try it on a safe item and see if it is the same.  This is more like staining or dyeing the item as opposed to putting a coating on it. It is just a method I have had good luck with and thought I'd share.