Excited to start your first watch build? You’ve probably been researching quite a bit recently about parts compatibility, the tools to use and steps to follow, as well as deciding on the final parts on the build. That’s probably how you landed on this post! In this guide we’d like to talk about watch gaskets - these parts are not often discussed because they’re just minor parts on a build, and most people focus on the parts that matter, like the case or dial. But make no mistake: gaskets matter too. Mishandling your gaskets will put a stop to your modding progress, so make sure to read up!

Many newer modders find themselves confused by the three main types of watch gaskets: crystal, bezel, and caseback. But don’t worry because in this guide, we’ll explain the functions and differences of these gaskets, helping you avoid common mistakes and ensuring your mods are correctly put together.


The Crystal Gasket

The crystal gasket creates a seal between the watch crystal and the case. Its primary function is to prevent water, dust, and debris from entering the watch, ensuring the dial and movement remain protected. Without a properly installed crystal gasket, even a small amount of moisture can damage your watch’s internal components.

Crystal gaskets are typically made from nylon, which has a stiff, plastic feel to it. However, not all crystal gaskets are the same; they may vary in height or thickness depending on the specific watch model. For example, we have different crystal gaskets for the SKX and SRPD, even though they use the same crystals. Our case bundles that include a pre-installed crystal also usually have a custom crystal gasket. Using the wrong gasket can lead to improper sealing or difficulty in fitting the crystal.

 

 

This gasket also has two main versions, the “L-type” gasket and the “I-type” gasket. The original SKX007 uses the former, which has a lower lip that causes the crystal to stand a bit taller. For Seiko mods though, the I-type gasket is much more common as most aftermarket crystals are already usually taller than OEM.

When installing a crystal gasket, it’s essential to ensure it sits evenly in the case groove. If it is even a tiny bit skewed when you press in your crystal, you will pinch the gasket causing it to deform, and unfortunately you cannot use this any more when this happens. That’s why we recommend getting spares if it will be your first time installing a crystal.



The Bezel Gasket

 

The bezel gasket is another crucial component, though its role is slightly different from the crystal gasket. This gasket sits between the bezel and the watch case, ensuring a secure fit while allowing the bezel to rotate smoothly. Without it, you’ll have friction between the bezel and case, which will add to wear and tear.

Bezel gaskets are typically made from rubber or silicone, making it much more flexible than the crystal gasket. The bezel gasket’s flexibility is key to its function, as it needs to accommodate the bezel’s movement while maintaining a tight seal. They come in different thicknesses, with the most commonly used one being 0.8mm (which is also the OEM thickness). Other bezels may require 0.7mm or even 0.6mm bezel gaskets for a smoother rotation - be sure to check the product descriptions to make sure you’re getting the right one! Too thin and the bezel might just pop off the case, too thick and your bezel could get stuck!

 

The bezel gasket is not as difficult to install as a crystal gasket, although it has its own set of challenges. Since it is more flexible, new modders may find it hard to align perfectly on the bezel groove and insert it. Pro modders find it helpful to use a small amount of silicone grease and using a pegwood to keep the gasket in place during installation. Once the gasket is seated correctly, the bezel can be pressed onto the case using a crystal press.



The Caseback Gasket

The caseback gasket is the third essential gasket in Seiko modding, and like the crystal gasket, its role is important when it comes to water resistance. Without a properly functioning caseback gasket, even a small amount of moisture can seep into the watch, potentially causing significant damage to the internal components.

Caseback gaskets are also usually made from rubber or silicone, same as your bezel gasket. In fact, these two look so much alike which is the common cause for confusion! When faced with this problem, just know that the larger gasket is usually the one for the bezel. Take note that they also come in different thicknesses, so double check that you are getting the right one for your build.

 

Installing a caseback gasket is probably easiest among the three, but you still have to be careful. Before placing the gasket, take some time to clean the gasket groove to remove any debris, or old gasket residue if you are reusing the caseback. Applying a small amount of silicone grease to the gasket can help it seat more securely and improve its sealing capabilities. When screwing the caseback into place, tighten it evenly to avoid warping the gasket or creating gaps in the seal.

One of the most common mistakes modders make is reusing old, worn-out caseback gaskets. Over time, gaskets can lose their elasticity and ability to form a proper seal, so it’s always best to replace them during a modding project. 


Wrap Up

Now that you know the ins and outs of watch gaskets, you’re ready to tackle your next Seiko mod with more confidence. These minor yet critical components make sure that your watch is water-resistant, functional, and built to last. 

Ready to start your next Seiko modding project? Do take a look at our collection of crystal, bezel, and caseback gaskets at namokiMODS, designed to fit a wide range of models like the SKX, SSK, SRPE, and more! Need more information about which ones to get? Contact us at support@namokimods.com 

Happy modding!

 

January 21, 2025 — Jeremiah A

Comments

edgar Staeger said:

what I miss is some information about the crown gaskets. Specially for divers watches.How to replace/handle them etc.Should they be replaced more often?

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