How to Polish a Watch Crystal

When a watch is brand new, the crystal is clean and clear of scuffs and scratches. But over time, your watch crystal may come to look less than pristine. If you want to get it looking like new again, you will need to polish it.

How do you polish a watch crystal? The answer depends on the material that your watch crystal is made of, most likely acrylic, hesalite, glass, or sapphire.

In this guide, I will explain how to polish each of these different materials so that your watch can look its best again. But first, a word of warning. Polishing an acrylic or hesalite crystal is fairly easy: the materials are cheap and the whole process can take just a few minutes. On the other hand, polishing glass or sapphire crystals is no easy task and you should seriously consider having the crystal simply replaced.

You need to be aware though that some crystals come with coatings to protect against glare. If you polish your crystal, you will rub off that coating (unless it is on the reverse side and you are not polishing that side).

So long as you are okay with that, we can proceed.

Polish an Acrylic or Hesalite Watch Crystal

If you are polishing a vintage watch crystal, there is a good chance that it is made out of acrylic or hesalite. In particular, almost all Soviet watches sport acrylic crystals.

Technically, hesalite is a type of acrylic. You are most likely to encounter it on a timepiece by Omega.

Omega Speedmaster with a hesalite crystal
Omega Speedmaster with a hesalite crystal / Source: @RichardMajor86

There are a couple of reasons why both acrylic and hesalite were so popular for vintage watches. From the manufacturer’s standpoint, they helped to cut production costs, and they were easy to work with.

But here’s the thing. While attractive and affordable, acrylic and hesalite are highly prone to damage. They just don’t have the hardness to endure a lot of wear and tear without showing the effects. Even fabric can scratch these materials.

Thankfully, there is a plus side to this. Just as acrylic and hesalite are easy to scratch, they are also easy to polish.

Let’s first check out the supplies you will require and the steps to revive your acrylic or hesalite watch crystals.

What Supplies Do You Need to Polish Your Acrylic or Hesalite Watch Crystal?

Not everybody uses sandpaper. But I figured I’d give the most comprehensive approach.

Polish an Acrylic or Hesalite Watch Crystal With These Easy Steps

1. Start by using the painter’s tape to cover the bezel. Make sure you cover it as thoroughly as possible. Doing so will prevent you from scratching or scuffing it on accident.

2. Carefully sand the crystal. As you do, spray it with the canned air to remove the dust. You might consider using several different grits, starting with a low grit and working your way up to a high grit.

Check on your progress regularly to make sure that you do not overdo it.

Sandpaper can be used to polish a watch crystal

Again, not everybody does this step. You will need to decide if it is necessary for your watch. Based on the overall condition of the crystal. If there’s only one small scratch, using sandpaper is probably not necessary. If there are many scratches though, sanding the whole crystal is a good idea.

3. Now you can squeeze out some polishing agent onto the crystal. Use your polishing cloth (microfiber works well) to rub it around with circular strokes.

Tabletop Vintage Watches
Tabletop Vintage Watches

Be absolutely certain you are using a soft enough cloth for this step! Remember, even regular fabrics that you wear each day can damage acrylic. If the cloth you use is too harsh, it could add new scratches instead of giving you a nice, smooth finish.

As with the sanding step, you need to make sure you are frequently checking to see how you are doing. That way you will not go too far.

Err on the side of being conservative; you do not want to press too hard and cause the same problems you are trying to correct.

4. Finally, remove the painter’s tape and wipe the watch with a clean microfiber or cotton cloth. Use some compressed air to clean any remaining residue, leaving behind a smooth, clear crystal.

Polish a Sapphire Watch Crystal

Now let’s talk about sapphire watch crystals. Sapphire is a much harder material than acrylic. It is harder to work with and more expensive than acrylic, which is why you will usually run into it in premium watches.

What is awesome about sapphire is that it is also much harder to damage than acrylic. On the Mohs hardness scale, it ranks at 9. That is almost as hard as diamond, which ranks at 10.

So, chances are good your sapphire watch crystal will be in great shape for a long time. But over time, like any other watch crystal, it may get scratched.

Depending on how severe the damage is, you might need to pay a professional to deal with the scratches, or you might just want to get a new crystal.

But if the scratches are pretty superficial, it might be possible for you to get rid of them yourself. As you will see, the process is one with which you are already somewhat familiar if you read the acrylic instructions above.

Some people will recommend that you don’t bother to polish sapphire on your own because it is more difficult than polishing acrylic, particularly without special equipment. And this is definitely true. Personally, I tried doing it once (using a dremel) and this was clearly not the best use of my time.

What Supplies Do You Need to Polish Your Sapphire Watch Crystal?

Use These Steps to Polish a Sapphire Watch Crystal

Polishing a sapphire crystal
Polishing a sapphire crystal / Source: @abo_hosni

1. The first step is the same as it is for cleaning an acrylic crystal, and that is to cover your bezel with tape.

2. Polish with the diamond paste using a dremel, starting with 2.5 or 3 microns, then finishing with 0.5 microns.

Be careful and avoid overheating the crystal and the watch. As with acrylic, you should check on your progress regularly throughout the polishing process.

Expect to have the polishing paste everywhere around you when you’re finished.

Take note that you are probably going to be scrubbing harder with sapphire than you have to with acrylic, even with the help of the diamond compound.

As I mentioned before, polishing a sapphire crystal is not a fast process, but this can definitely be done!

What About Polishing a Glass Watch Crystal?

Along with the materials we have already discussed, some watch crystals are made out of glass or a material called “mineral glass.”

What is the difference between the two? Well, glass is just glass. Mineral glass is an amalgam of glass fused with minerals that improve its hardness.

Tabletop Vintage Watches

Now, the easiest way to deal with scratched glass or mineral glass is this: just replace the crystal.

Why? You’ll see that the process is rather involved and requires special supplies if you want to do it yourself.

Unlike replacing a sapphire watch crystal, replacing a glass one isn’t that expensive.

But say you want to avoid that option and polish the one you have on your own. Let’s go over the supplies you need and the steps to get it done.

What Supplies Do You Need to Polish Your Glass Watch Crystal?

You’re already familiar with the items you’ll need: painter’s tape, soft cloth, safety goggles and a dremel or a buffing wheel with a polishing motor / drill. Instead of diamond polish paste, you’ll need some polishing rouge.

I’m not going to enter into detail regarding the process as it’s similar to what has been described above. You’ll need to cover the bezel with the painter’s tape, then use your polishing tool (dremel, polishing motor or drill) to carefully polish the crystal.

Caution: Do not add too much of the rouge. If you apply too much pressure or hold it against the spinning wheel for too long, you may overdo it. Not only that, but if you hold the watch in a single position for too long, you can actually mess up its shape, for example, by reducing its curve.

So, use light pressure when you first start, and work your way up to moderate pressure if you determine it is safe to do so.

If the rouge doesn’t seem to be sufficient, you can try adding more of that as well. But again, be cautious. It is better to start with too little than too much. You can always do more polishing on your crystal. You cannot undo it.

Frequently pause what you are doing. Use the polishing cloth to wipe away the rouge and check to see if you are doing okay.

Also, be aware that the friction generated by this process produces heat. Too much heat can damage the glass, so that is something you want to avoid. So, check the temperature of the glass. If it seems like it is getting a bit too hot, wait a few moments for it to cool off before you continue.

Tip: You might want to practice using the polishing motor and wheel with a spare crystal first before you try it on a crystal that you care about. Make sure you are practicing on as similar a shape and material as possible.

Also, don’t forget to wear your safety goggles during this process!

You May Be Able to Polish Your Watch Crystal at Home Using a Few Simple Supplies

We have shared supplies and steps now for polishing acrylic, glass, hesalite, and sapphire watch crystals.

It is pretty easy to polish most acrylic and hesalite crystals yourself with simple supplies and techniques.

Sapphire and glass can be more involved, but so long as you are not dealing with really deep sapphire scratches, you probably still can take care of most polishing jobs on your own.

Take your time, go slow, and check on your results frequently during the process. With patience and care, you can restore your watch crystals to full clarity, smoothness and shine.

How to Polish a Watch Crystal 1
Vintage Watch Inc

Dennis is the founder and editor of Vintage Watch Inc. Passionate about Soviet and Japanese vintage timepieces and a finance professional by day, he proudly wears a Seiko Pogue with his suit.

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