Can acrylic cracks be fixed ?

[Chopin]

Hello guys, I come with a question for those of you that probably have experimented around.

I have a watch with a crystal that has a few small hairline cracks (all the way down, so to speak) and I was just wondering if it wouldn't be possible to have them fixed/covered/filled by simply applying some type of adhesive that enters the cracks. I'm asking because I recently saw a video of someone fixing a cracked windshied by inserting some transparent adhesive into the cracks and they eventually disappeared as the adhesive dried.

The watch has a bit of an unusual crystal. I ordered an ATCH crystal but apparently it wasn't perfect. Apparently the vertical outer wall isn't as long as the old one (basically 2/3 through it starts to curve; measured bottom to top). (photo of the old one below, in case someone could help me name this type of crystal)

[AndyHull]

I suspect it may be possible, but equally it may be more problematic than it first appears.
 

1. One major issue is that any dirt in the crack will end up set in the repair compound, so unless you can ensure absolute cleanliness then the crack may still be noticeable following the repair.
2. You may need to pull a vacuum to get the repair material to enter the cracks.
3. You will still need to polish the piece after the repair to ensure an optically acceptable finish.
4. The repair material will need to set up (cure) with roughly the same refractive index as the original material.
   
   For the record, most of these crystals are probably a form of poly-carbonate, but this may not always be the case, and you would need to confirm what the crystal is made from to ensure the repair compound is compatible.

[rogart63]

Can be done . Have repaired some with acrylic powder and the solution for nails. Same that is used for prosthetics . But it doesn't work if it's in the middle of the crystal . It can be polished up to near perfect finish as it's the same material. You need to remove the old crack and get into the material that is good . Then fill it with acrylic. 

What size crystal do you need . And for what watch? 

I have a Certina DS 2 i crystals with similar cracks  can have a go at . And i can do a before and after. Have some powder left i think. Tomorrow evening. 

Edited November 24, 2019 by rogart63

[nickelsilver]

If you're talking about 'crazing' cracks, like deep in the material, there's no cure I'm aware of.

[Chopin]

Thanks guys, so that would be a no on my part, then.

It's not the size that is the problem but the height of the vertical edge/wall of the crystal. The ATHC starts to curb halway while the one that I need needs to be straight/vertical almost to the top of the overall height of the crystal (as the photo shows). I just don't know what type of crystal it is since it's clearly not an ATHC.