Why NOT to keep old yellow watch crystals

[Brad Maisto]

While looking for a watch to post in the “Threes a Crowd” (or something similar) thread, I came across this 60-second Elgin timer that I had saved the “original” yellowed plastic crystal. Much has been said about these old discolored plastics “outgassing” and causing steel watch hands to corrode. There was even an old rubber band, that was no longer “elastic”, holding the crystal and bezel in place. I plan to stop using rubber bands and trying to save “original” crystals. Lesson learned the hard way.
Brad Maisto, KY Floral #44 Secretary

 

[musicguy]

Every time I get a watch with a plastic crystal, the first thing I do
is pop it out directly into the garbage can. I do know that some
of the plastic crystals are fine and do not "outgas" but I like glass
crystals. I like the way they look, feel, and the weight associated with
them as well.

My buddy at Daves Watch Parts always has a great selection.


Rob

 

[grtnev]

Every time I get a watch with a plastic crystal, the first thing I do is pop it out ……….. I like glasscrystals. I like the way they look, feel, and the weight associated with
them as well.

Rob

Same here. When I send a watch in for COA, a standard part of that process, for me, is a new alloy mainspring and new glass crystal.

Richard

 

[topspin]

I can vouch that there is a strong correlation between "the watch came to me with a yellowed crystal" and "the hands were decidedly rusty".

The rubber band was probably put there by a non-watch person, either the original owner or a trader, who didn't see it as a good investment of time & money to do anything else.

As a collector who likes to see my watches running, I cannot think of a good reason not to replace such a crystal, any more than I can think of a reason to not replace consumable parts such as oil filters on an old car.

 

[kinsler33]

I no longer repair watches, but this is exceptionally valuable advice, for I always look at watches for sale as antiques even if I don't purchase a thing.

Thanks very much!!

 

[kinsler33]

I no longer repair watches, but this is exceptionally valuable advice, for I always look at watches for sale as antiques even if I don't purchase a thing.

Thanks very much!!

Another thought: could old rubber bands cause corrosion??

 

[Bernhard J.]

This is the first time I read about the corrosive action of plastic crystals. Perhaps a matter of when they were made? I admit that I myselfe never hat a watch with yellowed plastic crystal.

Cheers, Bernhard

 

[gmorse]

Hi Bernhard,

This is the first time I read about the corrosive action of plastic crystals.

The very early 'unbreakable' crystals, the ones which usually exhibit a yellow tint now, were made of a cellulose compound, and they did degrade and produce corrosive by-products. They were also extremely flammable! Ask any elderly cinema projectionist.

Regards,

Graham

 

[Uhralt]

Hi Bernhard,


The very early 'unbreakable' crystals, the ones which usually exhibit a yellow tint now, were made of a cellulose compound, and they did degrade and produce corrosive by-products. They were also extremely flammable! Ask any elderly cinema projectionist.

Regards,

Graham

That material would be celluloid.

Uhralt

 

[PatH]

This patent assigned to the E. Ingraham Co. specifically says celluloid. Sounded like a great idea, but it wasn't likely that much was known about some of the dangers associated with celluloid, such as the outgassing. As I recall, it was known early on that celluloid was explosive (as in the case of exploding billiards balls) and flammable.

 

[Uhralt]

I should add that celluloid is cellulose nitrate. The corrosive agent that is formed when cellulose nitrate decomposes is nitric acid.

Uhralt

 

[viclip]

Another thought: could old rubber bands cause corrosion??

Rubber bands sure cause a black streak to form over silver cases, let me tell you! I suspect that they contain sulphur. I know that sulphur will react with silver but I leave it to someone with a background in chemistry to opine as to the interaction between sulphur & nitrate cellulose.

 

[Uhralt]

Rubber bands sure cause a black streak to form over silver cases, let me tell you! I suspect that they contain sulphur. I know that sulphur will react with silver but I leave it to someone with a background in chemistry to opine as to the interaction between sulphur & nitrate cellulose.

Rubber does indeed contain Sulphur. The Sulphur is added to the raw rubber to harden and stabilize it. This process is called "vulcanization".

Uhralt

 

[viclip]

Rubber does indeed contain Sulphur. The Sulphur is added to the raw rubber to harden and stabilize it. This process is called "vulcanization".

Uhralt

lesson learned ... no more rubber bands around my silver cases anymore

 

[GeneJockey]

Hi Bernhard,


The very early 'unbreakable' crystals, the ones which usually exhibit a yellow tint now, were made of a cellulose compound, and they did degrade and produce corrosive by-products. They were also extremely flammable! Ask any elderly cinema projectionist.

Regards,

Graham

Ah, nitrocellulose! Back in the early days of Biotech, we used to use nitrocellulose filters a lot. It was always fun to hold one in tweezers, and light the bottom of the filter with a bunsen burner. *FOOF!* bright yellow flame, and gone in an instant.