I recently bought this late '60s Helbros Invincible skin-diver and the watch was beautiful. Nice sharp case edges, great looking dial, with matching yellow aged tritium hands. The acrylic crystal however looked pretty abused... a lot like a previous owner had used wool as a cleaning cloth. The crystal was covered with both superficial, coarse, and deep grooves/scratches. It was hard to show everything but here is a decent picture (before). A lot of the scratches aren't shown in this. It was bad. At certain viewing angles the dial became distorted.


I don't own Polywatch nor was I going to buy any as I knew it wouldn't cut deep enough to get the deep scratches, so I proceeded with wet sanding. I unfortunately didn't have any high grit paper on hand so I made do with 800 grit. (High grit between 1500 and 2000 would have just made the work faster). **For anyone wanting to try this: Take your time and mask off or remove the bezel. The last thing you want to do is scratch your bezel. Also, with even light pressure, sand across the entire surface of the crystal to create a uniform and smooth result. Sandpaper will eat through the crystal if you either apply too much pressure and/or focus the sanding just on the scratch (do not do this).

Here is everything I used. Note: I removed the bezel prior to sanding.


Now, wet the sandpaper and get to it


After sanding and you get your first glimpse of your work, you might sit back and begin to panic. Thinking "what the F@CK did I just do??" and begin to build up a cold sweat. But don't worry. You are on the right track.


Sand and review your work. Depending on how deep your scratches are, you might have to repeat. Be mindful of the soft curved edges of the crystal. You will want to follow those to avoid creating a flat-top.

Now to the toothpaste. If you don't have Polywatch, you can save yourself money and use what you already (hopefully) have- toothpaste. Toothpaste isn't just to prevent cavities as it is also a polishing compound. How else would you achieve white teeth? I first used my wife's Crest toothpaste but found it wasn't gritty enough so I used my Sensodyne. This is a lot thicker with a little more grit.



Using a soft cloth, apply firm and even pressure to rub the toothpaste (or Poywatch) in. Keep repeating until you achieve your desired polished result.


Now, this is where the high grit sandpaper would have made short work of the polishing. Because the 800 grit left deeper more spaced apart grooves (compared to say 2000 grit), I had to repeat this toothpaste step a lot more than I would have with higher grit. Here is the result after the "first" polish.



You can see the crystal is A LOT clearer than it was right after sanding. To spare you all very attempt, here is about 45 minutes later (after a breakfast break). The crystal is now "crystal clear."



With the bezel returned to the watch



Annnd a side by side before and after wrist shot



Thanks for reading a long!

 

Looks great!

Here's a link for a lifetime supply of assorted wet/dry sandpaper for crystal polishing for $10.
https://smile.amazon.com/gp/product/B01F6MDL7U/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

And a lifetime supply of polishing compound for $9.
https://smile.amazon.com/gp/product/B002UD0GGS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

Minty fresh!

 

But Dan, Novus doesn't have that minty-fresh taste!

 

9 out of 10 dentists would agree

 

"Looks too good for a 50 year old watch, redial!"





nice job

 

This is a nice how-to @Scarecrow Boat . I think many people are afraid to attempt aggressive measures like this and just live with the results of polywatch- which only works on micro-scratching. I think your points on keeping the pressure even and moving around the crystal (including the edges) is crucial. I've seen too many crystals that looked like icy tundra because someone worked a scratch too hard trying to get it out. Some scratches may just be too deep to get without taking way too much material down- and in those cases, just do the whole thing evenly and let that go- or replace the crystal.
One watch I got had been so aggressively sanded down and polished that I could see the surface deflect with just the slight pressure of my finger- if I pressed hard enough, I would have gone through it- I had to track down a long NLA proprietary crystal for that watch.
So, this is a great technique for any of us vintage lovers to have in ourtool kit- but like anything, moderation is key.

 

I would argue that your time is worth more than the ten bucks that crystal cost, because water resistance, etc... but as long as you do no harm, yay you!

 

Truuuuuueeeee but since this was everything I already had on hand, the ten bucks I pocketed I can spend on ice cream

 

Thank you! The first time I had seen "wet sanding" used for polishing was by @janice&fred and not gonna lie, it scared me. It's easy to think "sand paper... plastic... um what??" All I could imagine was me destroying the crystal haha. But, this was my first time and it was actually really easy and I found it enjoyable. as you know, I like working with my hands and taking things like cameras apart, so this was just another fun project. The crystal is thick, so going in I knew I had a lot to work with. I just took my time and kept any possible heavy hand in check. I can understand how people might be reserved on trying this approach, but it really wasn't a big deal at all.

 

I'll tell ya what, your end result was spectacular and a great example of how one can get the satisfaction of a hands-on job well done. Anyone can pay for a watch guy to replace a crystal but isn't that kinda contrary to the nature of this hobby?

 

Excellent post, have already ordered some 2000 grit paper. Have some skin divers in similar condition that could use a touch-up

 

Thank you! Yeah it was a simple but satisfying project. As said above a replacement part is cheap but the "project" had its own rewards that I would chose every time.

 

And as I've mentioned elsewhere, sometimes you really want to save a unique crystal on a vintage watch that can't be easily replaced. Now you have the confidence to do it.

 

Have fun! I found the whole project really gratifying. I took the time to clean all the gun under the bezel and it really made the watch feel and look new. The bezel rotates how it should and the dial really sparkles under the newly polished crystal.

 

Yup! And getting that practice in on a cheap crystal really bolstered up that confidence.

 

When the crystal cooperates.

 

Nice work dude and great score on the Helbros! Gonna have to bookmark this, A. Congrats

 

Very nice, I never done anything super deep. But I have used the sandpaper, i taped the whole area only option. My sicura should be here tomorrow, looks like it might need some crystal love.

 

Thanks for that link, on my cart already. I have some in stock, but always need more.