Author Topic: UK GPO 746 Topaz Yellow Telephone Restoration  (Read 3119 times)

Offline royalbox

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #15 on: January 20, 2017, 03:25:21 PM »
Thanks a lot TelePlay.
A couple of questions:
1. Is denatured alcohol the same as mentholated spirits? If so, I already have some.

2. Is acetone a thin liquid? If so, I'm thinking of what Andy said earlier about creating a fine mist. I was wondering about getting a small bottle that creates a mist (seen them on ebay) and trying that so there's no touching the surface with a rag. Could even do one side at a time so that the phone could be angled so there is no run off causing the possible problems that Andy mentioned.

Does that sound reasonable? I'd have to make sure or hope that the chemicals don't eat away at the spray bottle.

I've been sanding the grey phone case ready for testing. I know it's been said before but it really is a lot of work isn't it!

Thanks again,
Barry.

Offline twocvbloke

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #16 on: January 20, 2017, 03:27:21 PM »
Acetone is better known as nail polish remover, which is a watery liquid, though usually watered down a bit for use with removing finger nail paint... :)

Offline TelePlay

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #17 on: January 20, 2017, 05:37:38 PM »
Thanks a lot TelePlay.
A couple of questions:
1. Is denatured alcohol the same as mentholated spirits? If so, I already have some.

2. Is acetone a thin liquid? If so, I'm thinking of what Andy said earlier about creating a fine mist. I was wondering about getting a small bottle that creates a mist (seen them on ebay) and trying that so there's no touching the surface with a rag. Could even do one side at a time so that the phone could be angled so there is no run off causing the possible problems that Andy mentioned.

Does that sound reasonable? I'd have to make sure or hope that the chemicals don't eat away at the spray bottle.

I've been sanding the grey phone case ready for testing. I know it's been said before but it really is a lot of work isn't it!

Thanks again,
Barry.

Yes, here is a definition of Denatured Alcohol:  "Denatured alcohol, also called methylated spirits or denatured rectified spirit, is ethanol that has additives to make it poisonous, bad tasting, foul smelling or nauseating, to discourage recreational consumption. In some cases it is also dyed. Pyridine, methanol,[1] or copper sulphate[citation needed] can be added to make denatured alcohol poisonous, and denatonium can be added to make it bitter."

It's ethanol or ethyl alcohol (C2H5OH), the good stuff in pure form known as booze but it has been "poisoned" with inedible chemicals the have a boiling point so near to ethanol that they can not be distilled out, they come over at the same temperature making it near impossible to clean denatured ethanol. Methanol is CH3OH and Isopropanol is C3H7OH, neither of which is good to ingest. Both of which can be used to "cut" or dilute acetone to a desirable ratio.

Acetone is very thin and has a low boiling point (evaporates quickly at room temperature) was the original nail polish remover (probably in a diluted form) decades ago but today they have two types of remover, one with acetone and one made with everything but acetone. Pure acetone is very volatile and in a closed space and used in high volume, can evaporate to the point of having an explosive atmosphere where a spark could just wreck your day. Ventilation is good. Nail polish remover also has color and fragrance additives that may have a bad  effect on plastic. Pure acetone is available at hardware stores, home supply stores and paint stores by the quart or gallon. I buy it my the gallon because it is a great de-greaser to remove anything and everything from a metal surface I am going to paint (using a rubber glove on the hand that is holding the item to be painted) to keep finger oils off of the cleaned metal). A small amount on a paper tower works best be make sure to dispose the towels in an outdoor open can so the acetone can safely evaporate.

Back to plastic, I mix 10 ml of acetone with 10 ml of denatured alcohol as needed and the vapors from that are really not a problem if you keep the mixture capped.. When experimenting with chemical sanding, I started mixing acetone with water, 5% acetone, and worked my way up to 65% to get results. Since both acetone and denatured alcohol can dissolve plastic and WEBellSystemChristian found using pure denatured alcohol worked well on some plastics, I worked my way up to 50-50 which I like for ABS. A 50-50 mix works on a cloth by letting the acetone do its thing first, the acetone evaporates first leaving ethanol in the rag to smooth out the plastic softened by the acetone. It is a controlled process over a small area, a few square inches. Hard to keep a large area "wet" so smaller areas, say 1/2 the side of a 500 at a time. As you work with it, if you try this, you will see what I mean. It's best to keep rubbing an area until most of the liquids have evaporated leaving a fairly smooth finish ready for buffing or Novus.

Dipping for misting or washing a housing with acetone, MEK or DiChloroEthane to me is a mess and hard to control how much touches or stays on any part of the phone. It also will blur the emblem under the hand hold or on the handset. There is a topic somewhere on the forum where a member experimented with dipping but IIRC, it did not turn out well or it didn't work well. Also, if misting, you are creating an explosive atmosphere even faster. Also, the point of dipping is to "wash off" a layer of plastic so misting would not do much more than possibly causing pits or crackling. WE had a huge machine to do this in a very controlled process on a convey belt in an industrial type room. Somewhere on the forum is a pdf file that pretty well describes what they did and the chemical they used at temperature. Spraying acetone on plastic I think would be similar to spaying Windex on a dirty window and letting it dry by itself. Once you spray acetone on plastic, you can not rub the plastic with anything, or even touch it, without leaving bad marks in the plastic. If you ever accidentally had a drop of pure acetone hit anything plastic, you know what I mean. Instant damage.

You can use anything that dissolves plastic. Isopropanol does not cut as well as ethanol. Haven't tried methanol. Acetone cuts plastic very fast. MEK does as well. Water does not. The idea is to get a mixture that meets your needs. I do the 50-50 acetone/ethanol first and then pure ethanol. Christian just uses ethanol. As you go to large alcohols, butanol, pentanol, hexanol, etc, they become larger and thicker and don't know of they would do anything to plastic. Hexane, or rubber cement thinner, dissolves plastic but is expensive and hard to find. Butane is a gas and not sure what pentane is, probably has a volatility like acetone. Acetone is a ketone as is MEK, methyl ethyl ketone. MEK substitute is not the same.

If you don't have a junk housing to practice on, try your mixture on a small spot inside. If you cloth sticks to the plastic right away, use less acetone and ethanol or dilute pure ethanol with water. Each time I do it, I carefully watch the first application for problems and if none, just do the whole piece. If you do get a cloth mark or fingerprint (best to use a rubber exam glove to avoid fingerprints and to keep the chemicals from being adsorbed into your skin - I use a finger cot on the applying finger (1000 are cheap on eBay).

This was a lot longer than I thought it would be but I've been working with this technique for a few years, as has WEBellSystemChristian (and others including dencins who pioneered the use of chemicals on surfaces years ago).
            John . . .

              

Offline royalbox

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #18 on: January 21, 2017, 07:32:39 AM »
Thanks for all the info John and twocvbloke, really helpful.
I just ordered some acetone online as there are no descent shops that would sell it round here. I will try your method and post results.

I've been busy sanding the grey "practice" phone case some more. Really hard work, very discoloured but almost there. It has a crack on the front edge so I will investigate the best way to try and fix that in the mean time. I bought a small bottle with a dropper on the end in case that could be used to squirt a small amount of acetone in or around the crack to melt it together or something, but will read up on it first.

Thanks again,
Barry.

Offline royalbox

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #19 on: January 22, 2017, 09:45:15 AM »
I hope it's not considered off-topic, but while I'm waiting for stuff to arrive, here's some photos of the boring office grey phone I've been sanding.

1. As arrived, pre clean
2. Post sanding
3. Crack on front

I've glued the front with Humbrol poly cement and am holding it together with strong gorilla tape until it dries.

Barry.

Offline twocvbloke

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #20 on: January 22, 2017, 10:26:45 AM »
Looks like a nice job there getting the original grey back, the greyest I've seen on my 746 phones is not actually a 746 (officially) but my military Mk.28 (pictured below, middle phone, the left is an 8746 with Handset No.17A, and the right is a Pye-TMC 1746 branded as a Storno radio product), and even that's not entirely original to the light grey they used due to the usual age-yellowing, even though it's seen very little in the way of sunlight exposure... :)

Offline andy1702

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #21 on: January 22, 2017, 11:37:10 AM »
Three nice phones there Twocvbloke. Interesting variants on a theme too.

Barry, if you have any more cracked cases then it might be worth having a go at 'welding' the crack with acetone. There are a few threads on here about it, but basically paint a bit of acetone (or MEK if you prefer) into the back of the crack, which will seep into the crack with capillary action and stabilize it. Then you can 'v' out the front of the crack with a dremmel. You then mix some scrap ABS the same colour into a small jar of acetone. Keep adding the plastic until you have a runny paste. Note you might have to let it stand over night to get the plastic fully disolved on the acetone. You can then fill the 'v' with the runny plastic paste just a bit proud of the surrounding surface. Once dry, sand it flat and it seems (I haven't tried it myself yet) that the filled crack becomes totally invisible. I've seen cases with broken and missing parts built back up with this techniqe and it looks pretty good. The main thing to watch for is that you don't get any air bubbles in your mixture.

Having thought about it, I agree that misting probably wouldn't work. My guess is it would probably leave an orange peel like effect.

Andy.
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Offline royalbox

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #22 on: January 22, 2017, 12:42:14 PM »
Twocvbloke, Three grey ones! You must have quite a collection.

My grey one has a light grey dial ring that matches the case which seems to be less common. I sometimes see the 2-tone green phones with a light dial ring as well. Perhaps it depend on the manufacture.

The trouble with sanding -- apart from the hard work -- is that it does take away some of the sharp lines like on the rear of the 746 just before it curves up into the handle. Also, the line down the centre of the handset if you're not careful.

Andy, yes, that's what I had in mind, I've been reading those topics. I don't have a dremel but maybe I could use a small round file. I have acetone on order as mentioned previously so I will try it.

I have a green one with a crack in the same place as the grey one and a blue 746 that has a small chunk missing from the front corner. Rather than take away plastic from inside the phone I was wondering about buying one of those new dummy buttons and melting some of that. The 706 version is a bit cheaper at 2 including postage. I don't know how accurate the newly manufactured colours are though. Still, that's for later.

Barry.

Offline andy1702

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #23 on: January 22, 2017, 01:08:30 PM »
Barry,

Don't experiment on the blue one too much. It's the rarest original colour so you'd find replacing it or getting spare casing parts quite difficult.

I think the light coloured dial bezels came later than the dark ones. I've got green and grey ones here. I've also got a modernised 706 with a dial like a 746 that also has teh light coloured bezel.

I'm not a fan of sanding unless I absolutely have to do it. This is normally because something like glue has been dropped on the phone at some point in it's history or there are really deep scratches. If a phone is just discoloured I tend to live with it. I've got some quite nice two tone brown Ericsson N1900s that actually started life as grey ones, although you'd never know it now!

If you want original colours, then keep an eye out for 706s with Diakon cases. These were fitted up until 1963 and don't fade at all. They are also a lot more shiny than ABS. The Diakon finish almost looks like coloured glass. The down side of diakon is it's a lot more brittle, so you run the risk of damage if buying from someone who has to post it to you. I've had a couple from E-Bay that have been write-offs when they've arrived here.

You could try one of those new buttons as a source of plastic. It might be worth checking they're made out of ABS forst though as I don't know if other plastics would work the same. I might even be able to find a bit of something light green from the spares box here. I doubt I've got anything blue though. I'll have a look and get back to you on that.
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Offline royalbox

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #24 on: January 22, 2017, 01:32:07 PM »
Thanks Andy.

I repaired the crack in the green phone with glue like I'm doing to the grey one here. However, you can still see it's a crack if you look at it. I could probably "steal" a bit on plastic from inside on the green one but not really with the blue one as it's a chunk missing.

The blue one has quite a lot of deep digs and scratches etc, and so I would like to try and get it looking good again. This would be one that I will use as a main phone.

I've bought 7 phones and 3 of those came with cracks or breaks that appeared to happen during shipping. People just don't package them well, it's really annoying.

Barry.

Offline twocvbloke

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #25 on: January 22, 2017, 05:01:10 PM »
Three nice phones there Twocvbloke. Interesting variants on a theme too.

Thanks, it's the variations I like about them three, I'm not that much of a two-tone grey or ivory fan, so these three I have simply for those differences (and the 8746 was a bog-standard one but I had that 17A handset (bought from Bob Freshwater himself!!) that needed a home so that was perfect for it!)... :)

Twocvbloke, Three grey ones! You must have quite a collection.

It's been a while since I last counted, but, I think it's somewhere around 30-ish, most of which are GPO & BT phones with some US & Canadian phones thrown in... :)

Offline royalbox

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #26 on: January 29, 2017, 09:50:54 AM »
The acetone arrived.
I tried the 50% mix of acetone and methylated spirits on one side of the phone as John described. The results were a sort of satin finish, didn't really get rid of the fine scratches as I hoped. Probably need to mess about with the ratio a bit more. However, I really wanted to try the acetone vapour smoothing method, so I did.

I tried the dial bezel first. I used a biscuit tin that was only about 2 inches high, soaked a folded paper kitchen towel with acetone and placed it unfolded into the bottom. I put the dial bezel facing up onto a small piece of glass, placed that onto the towel and closed the lid. I left it for half hour, checked the progress and was really pleased with the results. It looked like new plastic, very smooth no sanding lines and no misshaping.

Next I tried the main phone case in a polypropylene box with a snap on lid. The box was about the right length and width but perhaps a bit high.

First, I placed two soaked paper towels, one each side held in place by the lid. After about 3 hours total, the result wasn't as good as the bezel. The sides were the best but the top just hadn't been affected enough. I re-soaked a piece of towel and placed it on the inside of the lid this time. Again, after 3 hours with checking in-between, the sides and back were good but the top wasn't. It had some crazing effect on it (see pictures). I'm wondering if it's because it's a horizontal surface.

Anyway, I'm going to sand it down and try again. I'll do the treatment John mentioned over the whole case first. I'm waiting for some magnets to arrive so I can attach the paper towels to the sides of the box more easily. I may add towels to all 4 sides but not the top and see how that goes. If I can get the top to look as good as the sides I'd be happy. I'd then use some Novus 2 as a final finish.

Barry.
« Last Edit: January 29, 2017, 09:54:02 AM by royalbox »

Offline royalbox

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #27 on: January 29, 2017, 05:48:14 PM »
Can anyone help me with covering the crack on the grey phone as posted earlier? The crack has been glued together but is still noticeable so I'd like to fill it with either glue or try to dissolve some grey plastic as shown in other threads then sand. The problem is that I need to create a groove along the crack in order to fill but I don't have a dremel tool. Any ideas on what I can use? I don't think a file will work, the crack is not straight for a start, but correct me if I'm wrong. Thanks for any help,
Barry.

Offline twocvbloke

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #28 on: January 29, 2017, 06:29:56 PM »
One way to create a groove is to just carefully scratch along it with the pointy end of a stanley knife (or similar) blade, takes a while but you get there in the end... :)

Offline royalbox

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Re: UK GPO 746 Topaz Yellow Telephone Restoration
« Reply #29 on: January 30, 2017, 10:41:48 AM »
Thanks twocvbloke, that worked well.
I'm currently building up a layer of dissolved plastic in the groove by dabbing it on with a brush until the acetone evaporates and then repeating as outlined in another thread. Apparently bubbles will form, but we'll see how it goes.
Barry.