Replacing a broken glass crystal

[Walt]

I'm working on a quartz watch marked only as "Swiss Army".  It has a glass crystal that was broken, and I was able to push it out from the back of the case, but now there are many small glass fragments stuck to the case with whatever adhesive was used to hold the crystal.  I'd like some advice on how to clean the case before installing the new crystal.

 

Walt

[LittleWatchShop]

36 minutes ago, Walt said:

I'm working on a quartz watch marked only as "Swiss Army".  It has a glass crystal that was broken, and I was able to push it out from the back of the case, but now there are many small glass fragments stuck to the case with whatever adhesive was used to hold the crystal.  I'd like some advice on how to clean the case before installing the new crystal.

 

Walt

A picture would be nice.  Apart from that.  If the case is separate from the movement and you have removed any and all gaskets, soak the case in acetone which will loosen any glue.  Using pegwood or similar, clear away any softened glue and glass.  Then rinse in water followed by a rinse in IPA.  The last IPA rinse may not be necessary, but it drives away the water.

Replace gaskets. Install a new crystal. Reinstall the movement. 

[Walt]

Thanks, I'll try acetone; I used lighter fluid but that didn't work. I don't know if you can make out the glass fragments it the upper right of the photo.

Edited May 21, 2023 by Walt

[LittleWatchShop]

Lighter fluid will not work

[Waggy]

Hi there, I second the advice of @LittleWatchShop most times IPA will work, I usually just use a cotton bud (Q-tip) dipped in IPA and hold it on a small area, then after 30 seconds the glue becomes gummy and can be picked/scraped out with a tooth pick, sometimes you have to go back over the same area a few times. I think acetone would also work but may evaporate too quickly for the method above, also acetone can eat away at plastics in seconds so most of the time I only use it as a last resort. Looking at the picture it looks like there is no plastic to be damaged so you should be OK with acetone if it is all you have, but if you have the option I would try IPA first, and then switch to acetone if the IPA wasn't working.

Once you have removed the glue/glass from the case, I would make sure you give the case and any parts which may have come into contact with the broken glass a really good clean as even a small fragment of glass the size of a grain of salt (or even smaller) can stop your watch dead in its tracks, or any dust could act as an abrasive and lead to excessive wear in any moving parts.

[StickDog]

MEK (methyl ethyl ketone) will dissolve about any adhesive if required. I'd try the above first because I'm sure MEK is not great for health. If nothing else works, saturate cotton ball or similar with MEK and leave in contact with the glue for 15 or 20 minutes. Then peel out softened adhesive with sharp pegwood or toothpick. Use MEK outside and don't get it on any plastics or finished surfaces as it will dissolve these promptly.  Available at hardware stores in USA. 

[pent]

Based on other adhesives I have come across in watchmaking, mineral spirits could work as well.  So far, they have dissolved every glue and epoxy I have come across.