If you were to ask a hundred amateur watchmakers, how do you repair acrylic watch crystals?99% of them are going to say Polywatch.

Although Polywatch is a pretty good product, it certainly has its limitations. If you’re working on vintage watches, you’re going to have to deal with acrylic watch crystals that are in all kinds of conditions.

Today we’re going to look at the limitations of poly watch and some other methods tha tyou can use to make your vintage watch crystals look brand new again.

If you follow these methods that I’m going to show you today, you will be able to get consistent results faster for less money and with a whole lot less work.

Why Use Polywatch at all?

So the first question a lot of people ask is, acrylic watch crystals are so cheap, why would you spend time trying to fix one when you can just replace it?

Well, actually there’s a lot of reasons to repair versus replace.

  1.  It could be a fancy crystal, meaning a crystal that has a certain shape that is extremely hard to find.
  2. You want to keep the watch as original as possible.
  3.  because sometimes acrylic crystals have a very unique tension ring inside them.
  4. You’ve tried to replace the crystal and you’ve ordered three or four and none of them seem to fit.
  5.  it’s just a matter of time. You don’t want to spend the time trying to figure out what crystal it is, ordering it, paying shipping for it, waiting four or five days, when you could literally polish the crystal in about five minutes and move on to something else.

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Polywatch VS Sandpaper

We’re going to do a comparison between two different methods of polishing acrylicCrystals.  That way you can compare the two to see how effective they are.

Scratching up the Crystals

We will start with two brand new GS crystals. I’m going to take the crystals, using a piece of 400 grit sandpaper and scratch them up to simulate what years of abuse would look like on a crystal.

Let’s look at them under the microscope real quick just so you can kind of see where we’ restarting at.

Scratched Crystal #1
Scratched Crystal #1
Scratched Crystal 2
Scratched Crystal 2

So you can see that both crystals are equally damaged and so scratched up you can’t really see through them.

Testing Polywatch Buffing by Hand

I you read the container, it says to use a soft piece of cotton. In this case, we’re going to use a new white cotton glove.

I will add a small amount of polywatch to the crystal, set our timer for three minutes and polish with my finger for three minutes.

When that three minutes is up,  I’m going to use a soft cotton buffing wheel with a little bit of additional polywatch polish. I’m going to give it one minute on the polishing wheel.

Results from 1st Polywatch Test

All right, so now let’s clean it up and see what it looks like.

Looking at it under the microscope, there’s clearly still a lot of scratching that’s left on the crystal.

1st Test Results
1st Test Results

So clearly three minutes of the polywatch is just not enough.

It looks like we’re going to need to do an additional three minutes of polishing. We’re going to set the timer for three minutes.

We’re going to add a little bit more polywatch, put three minutes on the timer, and here we go.

2nd Round of Polishing by Hand

Now we are going to repeat the 3 minutes of finger polishing and then an additional one minute with the rotary buff.

2nd Round of Polywatch Polishing
2nd Round of Polywatch Polishing

Let’s clean it up and look at it under the microscope again.

There’s still some scratching left in this one lower left corner, but that could have been just because I didn’t really get that area very well.

Overall it looks pretty good, but there’s definitely scratching that’s still left on the crystal.

Polywatch results -2nd test
Polywatch results -2nd test

Now I would imagine if you kept working it, it would improve, but just looking at thecrystal from this perspective, it actually doesn’t look too bad.

Those very minute scratches that I saw under the microscope, you’re probably not goingto be able to see them with your eye.

Sandpaper Test

For the second crystal, we’re going to use a piece of 1000 grit, a piece of 1500 grit sandpaper and a piece of 2000 grit sandpaper.

We’re going to use each grit for a total of one minute, the same as the three minutes that we did with the polywatch.

Polishing with Sandpaper
Polishing with Sandpaper

Then we’re going to follow that up with one minute of detail buffing.  For that, we’re going to use a product that I use called Polinum.

Now if you saw the video I did on watch lubrication, this is the same compound that I used to charge up a felt wheel when we were polishing the oilers.

We’re going to charge up a cotton wheel with it to do one additional minute of detailing after we do the three sandpaper grits.

Now I’m going to put the crystal in the movement holder just to keep it from flying and we’ll give it one additional minute.

Results of Sandpaper Test

It’s probably pretty hard to see but there are some very faint scratches that are still left around the perimeter.

It just looks like I might not have got the sandpaper all the way in all the way to the edge of the crystal itself.

Overall it looks really really good.

Now when that tests between the two methods of polishing crystals I would say that they’re pretty much the same.

Sandpaper Results
Sandpaper Results

If I had to pick one method personally I like the sandpaper method better just because it seems like it’s a little less work.

    Testing Polywatch with only a Rotary Tool

    For this test, I am going to take another crystal and 400 grit sandpaper and we’re going to scuff it up just like we did before.

    This time I’m going to use Polywatch and a cotton buff to do the entire buffing with my rotary tool  for three minutes.

    Be Careful of Heat Damage

    The one thing that you’re definitely going to want to be careful of if you’re using a dremel or any kind of rotary tool is you’re going to have to be very careful about heat damage.

    It doesn’t matter what you’re using, if it gets too hot it’s going to melt the acrylic and then the crystals just going to worthless.

    I’m going to try to keep a low to medium speed and we’re going to do it for a total of three minutes and then we’ll check it under the microscope.

    Rotary Test Results

    I see the remnants of scratches around the perimeter but for the most part it’s not too bad and it would be passable for many situations. It definitely doesn’t look bad when you hold it up and look at it.

    l would say with light or typical scratching on an acrylic crystal the polywatch actually did a really nice job with the rotary tool.

    PolyWatch with Rotary Tool Results
    PolyWatch with Rotary Tool Results

    Using Polywatch with Deep Scratches

    If you’ve got deeper scratches on a crystal how well is the polywatch polish going to work? I took a crystal and dragged it across the brick on the outside of my house a couple times and now we have deep scratches in the crystal that you can actually feel with your fingernail.

    Looking under the microscope you can clearly see the difference in the scratches that we have now versus the scratches that we were dealing with before.

    Deep Scratches in Watch Crystal
    Deep Scratches in Watch Crystal

    Testing Time

    I’m going to use my rotary tool with a cotton buff. Based on the results of our first test with polywatch, we know that a three-minute session isn’t going to do much. I will do a six-minute buff cycle and at about the three-minute mark I’m going to put more polish on the crystal and buff for another 3 minutes.

    Polywatch Results with Deep Scratches

    Looking under the microscope, I can tell just looking at it that those scratches are still very prominent and the polywatch didn’t really do that much at all.

    When it comes to taking out deep scratches, the abrasive in polywatch is not aggressive enough

    PolyWatch Deep Scratch Results
    Polywatch Deep Scratch Results

    Removing Deep Watch Crystal Scratches with Sandpaper

    Now we’re going to test the sandpaper method. Because I can actually feel the scratches in the watch crystal we’re going to start off with a piece of 800 grit sandpaper, then move up to 1000 1500 and then finally 2000 grit finishing with one minute of the polinum on the rotary cotton buff.

    Test Sanding Times

    I’m not going to time the 800 grit because it’s really just going to take as long as it needs. What I’m really looking for is for all the shiny areas on the crystal to be gone. The shiny areas are the parts of the crystal where the scratch is still deep so if you can see those shiny areas that’s where the scratch still hasn’t come out.

    We need to continue with the 800 grit until all those shiny areas have been taken out.

    After about three minutes of sanding with the 800 grit, all the deep scratches have been removed. I can now use the 1000, 1500 and 2000 grit and Polinum to bring the polish back up for a total polishing time of 6 minutes.

    Results of Deep Scratch removal with Sanding Paper

    I see one little scratch that I missed down on that corner. For the most part I would say that looks real good.

    Sandpaper Deep Scratch Results
    Sandpaper Deep Scratch Results

    More importantly, when you hold it up and look at it, it looks shiny and beautiful and that is good enough to put in a watch. I could work a little bit more on that one corner.

    When it comes to deep scratches you really have to be able to remove some material. If you can feel the scratch in the crystal with your fingernail you might as well just skip polywatch and go straight to the sandpaper method. The sandpaper method of polishing acrylic with polinum, will put a crystal back into new condition no matter how damaged it

      Conclusion

      If you have a some lite scratching on a acrylic watch crystal and no rotary tools, polywatch will remove lite abrasions.

      When you have deeper scratches there is virtually no amount polishing you can so to remove the scratches.

      If you are looking for a system to restore acrylic watch crystals, using fine grit sandpaper along with a polishing compound will be the easiest and most consistent way to achieve great results.