good (fri)day to you 
does anyone know what i'm talking about please:
one of our cats* stole my watch — which is my ecg, o2 sensor, and heart rate monitor — from its hangy place last night while i was in the shower and dragged it around (including down three tile stairs). the screen now has a small crack in it, and as replacing the screen will cost more than an as-new, second-hand** replacement watch 
, i'm trying to repair it.
husband is sure that there's some kind of glue that will go into cracks in glass and fill them invisibly. he says it's wetter than water and just spreads out where it needs to be when applied. have you heard of this?
if anyone could help with this, that would be amazing.
thank you
(and please boost, if you don't mind)
*pia, destroyer of watch
**i mean most watches are second-hand watches ... 
@moonrabbit windscreen repair kits for cars include it
@evilstevie
thank you. the stuff he's thinking of is thinner than that, but along the same lines. the crack is right at the edge, so theoretically not somewhere i touch?
tyvm again.
@moonrabbit found this stuff - am UK here, so regional links may need a shuffle:
loctite do a glass glue, should be searchable, this is one of the alternatives
@evilstevie
ooh thank you! that looks very interesting. and we could always get it sent to family in the UK for shipping on ...
tyty
@moonrabbit @evilstevie Whether it could affect touchscreen function depends on the design of the capacitive grid. It has to connect to the rest of the watch somewhere, almost always on an edge. If it’s laminated to the crystal, the crack made it through to that layer, and the crack is on the edge where the sensor connects to the rest of the watch, it could take out the whole sensor.
If the screen works now, it’s probably fine.
ooh thank you for this! v useful info. and yes it works totally fine now, so hopefully that part will remain stable.
do you think putting a tiny dab of some sort of glue that i've yet to find would be ok? the crack is *tiny*. husband looked with magnification and thinks it's more a tiny chip or deep scratch ...
(not committing you to anything here!! just asking for a non-binding opinion)
tyvm again.
@moonrabbit @evilstevie The glue plan is unlikely to make things worse. You need something with low viscosity so capillary action will pull it into the crack. Some kind of optical epoxy would probably be best, but I haven’t directly dealt with that world in a while.
Is the watch crystal glass or sapphire?
sapphire, i think.
(apple watch series 8, aluminium case)
@moonrabbit might screw with any touch-screeny stuff though, not sure how it interacts with coatings on glass I'm afraid