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Hampden single sunk face repair


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5 hours ago, thecodedawg said:

glued in place

when discussing vintage or basically anything related to American pocket watches pictures are a must because most people on this group are not familiar with them.

typically the dials are enameled copper. The  seconds dial is cut in and is a separate disk. I found some pictures online to show you what happens when they come out. The early ones are glued in with an unknown substance. It's usually kind of a light tan color. The later ones they used a special solder very low temperature and that's easily recognized as it's shiny silver colored. the soldered ones typically never are damaged it's only the early ones that can have issues.

as we have zero idea what the original substance was modern epoxy should work fine just make sure you get the little dial exactly where it's supposed to be. Also make sure the epoxy is flush with the dial itself and only put it on the backside.

but it would still be nice to see pictures of yours before you proceed. Just in case I guessed wrong.

porcelain dial 2.JPG

porcelain dial one.JPG

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15 minutes ago, JohnR725 said:

It's usually kind of a light tan color

Could they have used shellac?

It would make sense as it seems to be a pretty universal horological adhesive that a watchmaker would have to hand, would be easy to apply, and to clean up, and would allow repositioning if things weren't quite right.

Not as durable as the soldered solution though.

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9 minutes ago, Marc said:

Could they have used shellac?

considering that shellac is the universal glue it's what they should have used but it's not.

Back to searching online I found some more imagery examples of soldered dials. Then one of them you can see he has no recess the early dials there was no recess they hadn't perfected their techniques yet. Then I did find an example of our mystery glue.

 

porcelain dial mystery glue.JPG

porcelain dial soldered and not.JPG

porcelain dial solder.JPG

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2 minutes ago, JohnR725 said:

Then I did find an example of our mystery glue.

You're right, that doesn't look like shellac, more like old chewing gum!!!  🥴

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1 hour ago, Marc said:

 allow repositioning if things weren't quite right.

Important point here, I use a kind of glue which gives you couple of minutes to position things and would easily clean or can be removed in case there is a need to redo spot gluing, Once you call the position good, add stronger glue( stronger bond).

Heat damage is inevitable and will eventually show up somehow, I wouldn't solder.

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That glue is Interesting stuff.
Given the age of the piece, there are limited choices.
Possibly a latex based gum, which would be a reasonable choice to avoid cracking of the enamel. Good old fashioned chewing gum therefore is not such a daft suggestion as it was traditionally made from a whole bunch of different natural gums, including latex. https://en.wikipedia.org/wiki/Chewing_gum#Gum_base

Chewing gum takes quite  while to set though as anybody who has ever encountered it on a school desk or cinema seat can testify.

Possibly even something as simple as linseed putty (window putty), which again is semi-flexible, hence its use with window glass.

Maybe even an animal hide gum, but these tend to be brown or clear in colour.

Edited by AndyHull
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A little bit of reseach produced the recommended  by the NAWCC, site Elmers glue-all ( see picture) as the glue to use.  It looks as if its a pva based adhesive and therefore water soluable.    available on Ebay  £4.00

elmers.jpg

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PVA would be a good modern choice. Easy to use. Easy to remove. Semi- flexible, and a relatively long working time to allow careful re-positioning.

My observation from trying it as a filler on cracked dials is that you should clean things carefully first, as the water base will allow copper salts to dissolve and could cause a bluish green edge to appear around the repair.

So I would suggest, clean first with a cotton bud and a little white vinegar followed by a clean with fresh water (distilled if you have a lot of minerals in your supply) and a little dish soap. Dry carefully.

Then apply the glue. Spillage can be cleaned off the dial with a damp cloth. Once set, it is removable with acetone as far as I recall. 

Builders PVA probably has fungicides in it, which the Elmer's glue may lack.

Edited by AndyHull
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I glue on 3 -4 small spots with a kind of easily clean/removable glue that gives me couple of minutes before curring. Once I call it positioned, add more of final ( strong) adhesive.

Heat will inevitably cause some damage, whose effect will eventually show up, perhaps months later.

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1 minute ago, Nucejoe said:

Heat will inevitably cause some damage, whose effect will eventually show up, perhaps months later.

I agree. Enamels can be very prone to micro cracking.

The same is true of a lot of ceramic components in the electonics field.

If you can, avoid heating ceramic parts unless they are specifically designed to be heated.

Glass and glasswear can be annealed, and this is typically how the heat stress is removed from enamelled dials when they are fabricated.

The rear of the dial is enamelled first. The use of enamel on the rear avoids the substrate flexing uneavenly when the dial side is decorated and the dial side enamel is fired, and allowed to cool. Once the initial cooling has occurred then the whole dial is inspected to ensure it is perfect, then heated again in an annealing stage to a temperature just below the melting point of the enamel amd allowed to cool much more slowly and this allows the heat stresses to balance out and the crystal structure of the glass to form more evenly.

There is obviously quite a bit more involved in the process than this, but it does highlight the importance of minimising heat stresses in glass enamelled parts.

If you solder, even with a low melting point solder then you also run the risk of boiling off any trapped moisture in the enamel, which will cause tiny steam explosions which will crack and flake the item.

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Hide glue is most likely what was originally used. It can be had from luthier supply houses if you want to remain true. 
 

Personally, after a thorough cleaning, I’d use G-S cement. It’s strong clear and flexible. 

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10 minutes ago, Tudor said:

...

Personally, after a thorough cleaning, I’d use G-S cement. It’s strong clear and flexible. 

That is also a good suggestion. It would avoid the moisture of water based PVA, which might be undesirable in this application.

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I, also, would recommend the G-S.  I work on pocket watches and am learning more about dial repair.  I believe Tudor is correct in saying that hide glue is what was originally used.  Outside of shellac and hide, there weren't very many different kinds of glues available during the time that watch was made. The residue I have encountered has the same smell, same consistency with age, and reacts to moisture in the same way as hide glue.  In most areas, hide and shellac were all there was.  I have some hide glue, but I think the G-S would be better for this repair.  And it will be less prone to weakening in situations of high humidity.

Edited by KarlvonKoln
typo
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THanks for all the answers. I will get pics shortly.  I have been very busy with family and work over the past week or so. I apologize for being inattentive on this post....  

In the first image, you can see a 2 to 3 mm gap between the edge of the seconds dial and inside of the cut in the main face.  

There is a very minimal overlap between the face and the copper backing. This means that I have almost no gluing surface on the front. Whatever I use to glue this together will have to fill that gap and hold the watch together. I was almost thinking about using silicone caulking

Devon

20201208_094539.jpg

20201208_094426.jpg

20201208_094420.jpg

Edited by thecodedawg
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