Author Topic: Broken bakelite  (Read 10478 times)

Offline McHeath

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Broken bakelite
« on: September 09, 2008, 10:33:49 PM »
After reading about Bingster's E1 handset woes I was reminded of the issue with my G1 handset on my old 500.  (I don't really have a lot of old phones)  The microphone cap is cracked, looks like someone struck it on something and there is some spiderweb cracks right by the edge where it rolls down and then long cracks into the holes on the face and down to the skirt on the side.  So far I've just been careful with putting it on the phone and handling it, I'm wondering if there is anything that can be done to shore it up or stabilize the crack?

Offline Mark Stevens

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Re: Broken bakelite
« Reply #1 on: September 10, 2008, 05:04:05 AM »
I've never tackled such a repair, but have found quit a bit about it from sources pertaining to old radios, cameras, and even vintage cars.

Here's an excerpt from a British site:
"Advanced bakelite repairs It is possible to repair broken bakelite in a way that is very hard to detect. The first thing is to make solid joints and if you are lucky, you can piece the bits together and glue them in place with superglue (cyanoacrylate). Doing this slowly and carefully is the main secret; it may take quite a bit of  'dry runs' to get the three-dimensional jig-saw to go together properly.  Plasticine will help keep the pieces together while the glue cures.  For pieces under mechanical stress, superglue will probably not work; in this case you will need to use a modeller's drill to make holes for inserting short pieces of wire to pin the joint in several places.  A traditional slow-setting epoxy glue such as Araldite is used to make the joints and this can be built up behind the joint out of sight to give added strength.  When  nearly set, surplus Araldite can be trimmed away with a sharp blade. An alternative method which also has a lot to commend it is the use of glass-fibre cloth and resin (bonding paste), as used for patching car bodies. The materials are used on the inside of the case to be mended and the trick is to use a file or grinding tool to thoroughly roughen the surface. Using a putty knife or wooden spatula, the roughened area is then covered with a thin layer of resin (about 1/16th inch thick). A piece of glass-fibre cloth is then pressed on, smoothed out and left to cure. Once fully set another thin layer of the bonding paste is spread over the cloth for extra strength. This can be sanded for a smoother finish if desired when cured. Yet another possibility is Loktite BlackMAX adhesive, which is  a cyanoacrylate that has rubber dust loaded into it. This helps the impact resistance and also gives a black colour. Some hairline cracks will remain and these can be filled with the self-curing black resin body-filler paste available at auto accessory shops. Once cured you can use very fine wet-and-dry paper (as used for car body work) to smooth the joints until they can no longer be seen or felt. Finally polish with Paste Polishing No. 5 (Baykobrite). For brown bakelite you could mix artist's powder paint with clear epoxy glue but be sure to mix in the powder extremely thoroughly."
Whew! Here's the link to the whole thing:  http://www.thg.org.uk/info/plastics.htm

This came from a vintage camera forum:
"Bakelite is basically one huge molecule. You can not dissolve that! If you want to glue bakelite, sand the area to make it rough and use slow epoxy. If you want to achieve a good bond, do small holes with a dremmel around the crack and "sew" the crack with copper wire before applying the epoxy."

From an Australian radio site:
"Iíve normally used 5-minute Araldite but with the rubber strap employed, the longer setting version could be used. If you have any doubts about the freshness of your Araldite, open a new batch."
Link:  http://www.siliconchip.com.au/cms/A_101790/article.html

A British radio site:
"Repairing Bakelite cracks is one of the most difficult tasks in radio restoration. Anyone can glue a crack together using 'Devcon' plastic weld. But to repair a crack so that no marks are left behind is another matter. A Dremel tool is used to make such a repair. First you would cut a grove along the crack and save the dust. Also grind some more plastic dust from somewhere inside the cabinet. Mix with clear epoxy cement and fill the groove over the crack. Grind or sand the cement down. Then polish with rouge to get an even polished surface. It takes a lot of practice to get the expertise needed to make such repairs a success."
Link:  http://www.richardsradios.co.uk/repairing.html

Regarding bakelite distributor cap repair, this was posted in a vintage car forum:
"If you grind out the crack with a V using a Dremel tool and fill it with 2 pack epoxy it should work OK. Use a product called Araldite or a similar product, but make sure it's the 24 hour stuff not the 5 minute. We used to do repair jobs all the time in my early years as an electrician using this method. A problem you will have is that the glue will tend to run out before it sets. Use a heat gun ( or hair drier ) sparingly to heat up the mixed glue before you add it to the joint. And maybe work it a little as it sets over a period of a few hours to keep it in the crack. Once it goes off leave it alone until set completely, usually give it 48 hours to be sure."
Link:  http://forums.aaca.org/ubbthreads.php/topics/536265/Re_bakelite_distributor_cap_re

A vintage radio site:
"Clean cracks and breaks can be successfully repaired with a little superglue. Do not apply the glue directly from the bottle, as you will get far too much. Place a few drops on a piece of scrap card, and use a pin or piece of wire to apply it to the crack or break. In the case of a crack, apply the glue to the inside of the cabinet and let it work its way into the crack by capillary action. Once the glue is thoroughly dry (allow several hours), any excess can be gently removed with a razor blade or modeling knife."
http://www.vintage-radio.com/repair-restore-information/general_restore-cabinet.html

Found this from a site that kept crashing my computer...they don't get a link.
"Superglue is only suitable for repairing clean breaks, and is unable to fill even small gaps. If the broken parts do not fit cleanly together, you will need to use an adhesive that fills the void. An epoxy resin such as Araldite (the standard type, not the fast drying) is suitable. Any excess can be removed with a modeling knife once the glue has dried completely (at least 24 hours)."


Many references to "Araldite," a substance I'm not familiar with. Usually mentioned on British or Australian sites, it could be a trade name not used in the U.S. (or I could just be out of touch!)  For whatever reason, the Brits seem to address bakelite issues more often than Americans, so many of the products referenced are unknown here. Most of this is in regards to more complex repairs than you're faced with, but I thought that determining the appropriate type of glue/epoxy to use with bakelite would be a key to success.  Applying to the back also seems wise from an appearance standpoint. Of course, one could always take the coward's way out and replace the cap! Nah.
Although he specializes in 500s, Dennis knows his stuff, and might chime in with some good ideas.
- Mark

« Last Edit: September 10, 2008, 07:47:38 AM by Mark Stevens »

Offline Dennis Markham

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Re: Broken bakelite
« Reply #2 on: September 10, 2008, 08:17:35 AM »
Mark, it looks like you did some homework on the issue of Bakelite.  Thanks for the vote of confidence with regard to my knowledge of the issue.  I have read about and talked with collectors that have made major Bakelite repairs to their telephones.  Although I have made repairs to cracked thermoplastic telephone covers, I have not done any work with Bakelite.  However I have read the experiences of other collectors on the List Serve of both telephone clubs to which I belong.  Also a friend and fellow phone collector is currently working on a Bakelite repair on a vintage Kellogg "Ashtray" telephone.  The process is quite extensive.  When he is finished perhaps he will share photos and tips with us. 

The product that the experienced collector's use is J.B. Weld.  It is an automotive product.  J.B. Weld is available at any automotive store---it's not expensive.  Apparently there is a one minute J.B. Weld and a longer one, some time under ten minutes.  That is the time for the product to harden.  I have used J.B. Weld in an automotive application.  It hardens like steel.  The J.B. Weld is used to fill a large broken area or to fill in a crack.  Once hardened it must be sanded and blended in with the original Bakelite.  Painting is possible.  The repair will not be invisible but will be better than a hole.  I would imagine black Bakelite is the easiest to repair as far as blending colors.  But since there is plenty of colored Bakelite out there, phones and radios I would imagine it takes some experimentation.

For thermoplastic repair on large chips and cracks there is a way to similarly make a repair putty, fill the hole, let it dry, file the excess away and then began a sanding process using wet-sand automotive paper, gradually going to finer grit papers and polishing.  Matching colors is again the difficult part.  Another topic for another time.

As far as the Bakelite mouthpiece cap, my advice is to obtain a replacement.  I encourage member ship in one or both of the phone clubs.  Membership allows access to the List Serve where collectors often offer parts or phones for sale at a much lower price than what one can find on eBay.


Offline Mark Stevens

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Re: Broken bakelite
« Reply #3 on: September 10, 2008, 09:16:20 AM »
Mark, it looks like you did some homework on the issue of Bakelite.
It's my penance for slacking-off in school...now I love homework!

The product that the experienced collector's use is J.B. Weld.  It is an automotive product.  J.B. Weld is available at any automotive store---it's not expensive.  Apparently there is a one minute J.B. Weld and a longer one, some time under ten minutes.  That is the time for the product to harden.  I have used J.B. Weld in an automotive application.  It hardens like steel.
Really?! Long ago I blew the clutch in a motorcycle, resulting in a quarter-sized hole in the aluminum case. I fitted a piece of aluminum to the hole and applied J.B. Weld. It worked great!  I had no idea it would be suitable with bakelite. I knew you'd come through!

Offline McHeath

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Re: Broken bakelite
« Reply #4 on: September 11, 2008, 01:36:40 AM »
Wow a lot of options!  I probably could replace it I guess, but I think I will give the J.B. Weld a try first. 

Offline HELLO CENTRAL

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Re: Broken bakelite
« Reply #5 on: September 11, 2008, 09:14:50 AM »
Sorry, didn't read all of the above.  Household hint useful here?  A while back, I bought  and sold a whole collection of bakelite jewelry.  I was told to clean it with mineral oil.  Which I did.  ???
HELLO CENTRAL.

Offline Dan/Panther

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Re: Broken bakelite
« Reply #6 on: September 20, 2008, 07:22:30 PM »
I have had tremendous luck with cracked bakelite,  by making sure the crack is VERY clean,  and securely glued baclk together,  I then  "V" the crack slightly. Then make sure the crack is absolutely clean. I then run super glue the length of the crack, when that dries, I add more super glue until it is slightly above the surrounding bakelite. CAREFULLY using a very fine curved ended file, I file the supoerglue, until it is flush. Then Use Brasso to polish out the finish, The super glue is actually harder than the bakelite.
Herer is a photo of a repair using the above mentioned procedure.

Dan/Panther

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Offline Stephen Furley

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Re: Broken bakelite
« Reply #7 on: November 05, 2009, 02:40:42 AM »

Many references to "Araldite," a substance I'm not familiar with. Usually mentioned on British or Australian sites, it could be a trade name not used in the U.S. (or I could just be out of touch!)  For whatever reason, the Brits seem to address bakelite issues more often than Americans, so many of the products referenced are unknown here.

Araldite is epoxy resin; it is a trade name, originally by Ciba, but in recent times passed to another company, but I can't remember the name at the moment.  There are many Araldites, not all of them are even adhesives, some are things like potting compounds.  Most of them are only available in large quantities for industrial use, and are identified by numbers, but one type was made available in the '60s in small tubes for home use, and was simply known as 'Araldite'.  Later another type was also made available, branded as 'Araldite Rapid'.  Recently I saw a third type in a shop, but I don't know what it was.  The standard home packs contain 15ml each of resin and hardener, but a larger size is also available.  The industrial products come in various sizes of tins and drums, but you wouldn't find them in shops.

When first introduced the small tubes of Araldite cost six shillings (30 pence, or about 50 cents) this was quite a lot of money at the time for such a small quantity, and Araldite was regarded as a very expensive adhesive, but nothing else similar was available.