Shellac to fasten crystal?

[Woolshire]

I have an old watch with a sapphire crystal that appears to have been fastened with shellac. I’m assuming that was factory work in 1925. The crystal has been taped on while the watch sat in a drawer over the last 50+ yrs.

does anybody still flow shellac into the crystal bed on the case? Obviously, there are better choices today, but how big of a deal is the originality of this on an old expensive watch?

[KOwatch]

Not sure when the first sapphire watch crystals became available, 1925 seems too early as the process for creating synthetic sapphires was first developed  after 1910.  Rolex didn't start using them for watch crystals until 1970, so if this was factory work it would predate this by 45 years.

Otherwise there were watches made with natural sapphire crystals also. Must be quite the watch. Can you post a photo?

Do you think the shellac was applied as a thick varnish adhesive, or flowed with heat? Seems like shellac would be a logical adhesive choice for 1925.

[HSL]

I think you could use something more modern on a watch like this too. 
This is what I use on vintage watches. 
https://www.ebay.com/itm/Seiko-S-314-UV-Activated-Watch-Crystal-Glue-Adhesive-/172508493372

Here you can see it in action too.
 

 

[JohnR725]

4 hours ago, Woolshire said:

I have an old watch with a sapphire crystal that appears to have been fastened with shellac. I’m assuming that was factory work in 1925. 

I'm in agreement with the above posting 1925 seems a bit early for a sapphire crystal are you sure it's not glass? Then doubtful it was shellac I don't think I've ever heard of that being used to glue with a crystal. Then they do make glue for crystals but the most common thing now is epoxy glue.

[Woolshire]

I could be wrong, but seems to be real sapphire. So, what did they use as a glue back then? Specifically, on non-round crystals? I know a round case is sometimes heated to fit a crystal.

[dadistic]

G-S Hypo cement has been around since the thirties,  commonly used to affix crystals.

1925? I'm not sure G-S Hypo goes back that far. 

 

[JohnR725]

20 minutes ago, Woolshire said:

real sapphire

If you touch a sapphire crystal it will have a cold feeling. It's better at conducting heat then glass.

Looks like from Wikipedia your right synthetic sapphire came into existence In 1902.

 

6 hours ago, Woolshire said:

old expensive watch

Out of curiosity what is the name of this watch?

 

Unfortunately it's a little early but at the link below you'll find a catalogue of 1899 of watch supplies and optical supplies. Conveniently on the crystal page it doesn't say how they're fastened. But in the optics section of course there is optical cement for gluing lenses together which conceivably was used here.

https://archive.org/details/20thcenturycatal00purd

[dadistic]

Here's the page.  Unfortunately, doesn't say much about what it is. 

[oldhippy]

Rubber based glue was around in the Victorian period also fish glue was popular 

[JohnR725]

Here's a link that might find interesting.  It was helping with my memory I was trying remember this Canada Balsam. Basically early glue for lenses  and you look at what it is  kinda like a weird form a shellac in a way  very likely what they might've been using.

http:// [Search domain wp.optics.arizona.edu/optomech/wp-content/uploads/sites/53/2016/10/ClementsTutorial1.doc] https://wp.optics.arizona.edu/optomech/wp-content/uploads/sites/53/2016/10/ClementsTutorial1.doc

https://en.wikipedia.org/wiki/Canada_balsam

[Woolshire]

Wow...thanks for the detective work and info! The watch is a Patek. I’m thinking if anyone used sapphire for crystals, it would be them.

I did get the goo off the crystal and case, using just a small amount of naphtha. Didn’t disturb any patina, at all. I also got the old dried shallac-like stuff off with just a softened toothpick.

 I’m pretty sure the crystal is sapphire and original. 
I am still wondering about the best way to glue it. It fits nicely, but not going to stay in without glue. I know the likely best option is clear epoxy, but am wondering if figuring out exactly what was used at the factory (and if using that) falls into that whole originality concept.

[JohnR725]

If you really want to know about your watch I have a link. But maybe you could just ask a question like  what was originally used to hold the crystal in and what do you use now?  Who knows they might answer

https://www.patek.com/en/retail-service/extract-from-the-archives

[KOwatch]

6 hours ago, JohnR725 said:

Looks like from Wikipedia your right synthetic sapphire came into existence In 1902.

Unless my wikipedia reading is incorrect, 1902 is for  synthetic rubies, these would have been small red crystals. They achieved blue sapphire in 1911, again gem-sized, but not gem-quality. I really don't think they had the abilities to create watch-sized optical quality crystals until much later. Depends on the size of the watch, of course. But if it's optically clear and not tinted at all, I'd be suspicious. I'm pretty sure I've seen a photo of a watch covered by a polished natural crystal, but very old and not very clear.

I suspect the advancements enabling watch crystals to be made with synthetic sapphire came from the semiconductor industry, which would correlate with their wider introduction starting in 1970 on the beta21 quartz models.

Interestingly, with all the writing on watches out there, I can't find a good article on the history of using sapphire crystals in watches. Good subject for someone to write an article.

 

 

[JohnR725]

20 minutes ago, KOwatch said:

Unless my wikipedia reading is incorrect, 1902 is for  synthetic rubies, these would have been small red crystals. They achieved blue sapphire in 1911, again gem-sized, but not gem-quality. I really don't think they had the abilities to create watch-sized optical quality crystals until much later.

I was trying to be agreeable and cheerful not my usual critical negative self. Out of curiosity I asked at work today because we put a lot of sapphire crystals in For the fun of it I asked my boss. Perhaps the 70s and that would be 1970s not 1870s.

There is another alternative perhaps?  Another possibility would have been quartz optical grade quartz crystal. I'm pretty sure that larger pieces of natural stone. Zero idea when they synthesized quartz.

[mikepilk]

Sapphire watch crystals may have come about as a bye product of the defence industry. Single crystal sapphire was grown to use as sensor windows for infrared sensors and missiles, due to it's toughness and being translucent to infrared.  

So possibly created late 50's - 60s, but the military wouldn't want it out in general use. My guess would be no earlier than the 70's ?

[Woolshire]

I am familiar with the Patek website.  I’m guessing they won’t tell me anything about the glue they used then or now. But, good thought and I will submit a question.
This sure looked like shellac. However, I would think that they would have used something more colorless. Maybe this was colorless back then????

It sounds like we’re not sure what was used originally. Fish glue or potentially a rubber-based glue...or a near-colorless shellac

As for current times, clear epoxy is commonly used. UV glue and G-S are also popular. Since this isn’t something that seems to be a “originality” issue, I need to choose one that will hold the darn thing on, and move forward.