In the last post, we saw a trio of watches I received that belonged to my late second-cousin Frank. I thought I’d start with the Seiko, which is unlike anything I own. It’s in rough shape.

Taking Stock

The most obvious flaw is the crystal, which is cracked and chipped. The crown feels seized: it turns but won’t easily pull out to the setting position. And the watch doesn’t tick. For a quartz watch, most of the time, it’s a dead battery. Let’s pop off the back and see what we have.

Well, we have a lot of green, grimy paste, which is the usual gross mix of sweat, oils, bacteria, and skin cells. Watchmaking isn’t always glamorous. Inside is a Seiko 7N00A, an unjeweled quartz movement and a workhorse of many 1980s Seiko dress watches.

I’ll start with a new battery. I have a stash of batteries because when friends ask if I can fix something, they usually have a quartz watch. Fortunately, I have a few of the battery I need: size 364.

Then it’s time to remove the movement and take apart the band and case for cleaning. I carefully push out the crystal over tissue paper to avoid spreading tiny glass fragments. This crystal looks like it was glued in, so I scraped the bezel with pegwood to remove as much of the adhesive and tiny glass fragments as possible.

Before discarding the crystal, you need to measure it. The inner diameter of the case is 30.0 mm, and the crystal is .80 mm thick.

Time for a bath! All the case parts got a thorough scrubbing in the ultrasonic cleaner. A heated ultrasonic cycle is the best way to get grime and grunge from a metal bracelet. There are so many little holes and crevices that a toothbrush can’t reach. Notice how the tiny parts (the spring bars and stem) go in a little basket so they don’t get lost.

Normally, I’d polish the case and bracelet to remove minor scuffs and restore the shine. In this case, it is too risky. This Seiko has a base metal case with two-tone plating, most of which has worn off. The bracelet is probably steel and has equally worn two-tone plating. The heat and pressure of buffing could make the plating flake in weird and unexpected ways.

This, by the way, is why base metal cases are always less desirable than stainless steel or even gold-filled cases when you’re hunting for vintage watches.

Replacing the Crystal

Knowing how to replace crystals is a handy skill. I suspect that people will put up with a lot in a favorite watch—scratches, grime, and scuffs—but once the crystal cracks, the watch goes in the drawer. That’s probably what happened to this watch.

The crystal was a simple, flat mineral glass crystal: 30.0 mm in diameter, .8 mm thick. A flat glass crystal can be set in a couple ways. The method used originally was glue. In a modern watch, a glued-in glass crystal is a sign of a pretty cheap watch. The best bet is UV glue, which dries clear and is handy for pocketwatch crystals.

The other method is to set the crystal into a compressible gasket. Under pressure, the gasket molds to fit both the crystal and the case. This is the more common method and the standard method for cases intended to resist pressure and water. This video discusses the process and shows you how to do it.

I’ll go with the gasket method because it’s more interesting and I haven’t done it for a while. I have an assortment of gaskets and crystals that I picked up a while ago.

Most of these are flat 1.0 mm mineral glass crystals. The box has some handy extra spots for random extra crystals and gaskets I’ve ended up with over the years.

As the video points out, you usually need to try a few sizes despite your best measurements. Gaskets have an outer diameter (i.e., the case or bezel opening), a height (.8 mm here), a width (.35 mm), and an inner diameter (27.30 mm). For the height of the gasket, you should pick a gasket that is shorter than the crystal. I’m going to use a 1 mm crystal, so a .8 gasket is the right size. If the crystal and gasket are the same height, it will look weird. If the gasket is too short, it won’t grip the crystal.

In this case, the glass crystal’s diameter is 27.4 mm—technically bigger than the gasket, but it works. Differences in manufacturing tolerances and measurement error make it worth having an assortment of sizes on hand.

Gaskets come in two shapes: I-form and L-form. The L-form gaskets are used when pressure-resistance is important. The crystal sits on the lower lip of the gasket, so as pressure increases, the crystal is pressed deeper against the gasket seal. L-gaskets are standard in dive watches and pretty much any modern watch with a substantial case and big, thick crystal. I-form gaskets lack the lower lip and are slightly beveled, so they’re used when a thin, unobtrusive gasket is called for, like dress watches.

Because gaskets seal the crystal to the case via compression, you use a crystal press to insert them. I’m using my trusty Horotec press and dies. This set of dies is perfectly flat for giving even pressure on the face of the flat glass crystal.

This watch came with a .8 mm thick crystal, which was flush with the case as Seiko intended. I went with a 1.0 mm crystal, largely because it’s what I have on hand but also because I like the slightly stepped look—it gives visual depth to an otherwise flat watch face.

Wrapping Up

After inserting the crystal, the case looks great—clean, shiny, and attractive. As a final step, I lubricated the stem and keyless works, and the watch’s setting action greatly improved.

Overall, I like to look of this watch. It has a clean, appealing dial and good legibility.

I have a few small things to wrap up: the case back and stem need a new gasket, and the bracelet is just a bit too tight.

I have no idea where I’m going to find links for this. Seiko made a bazillion styles of quirky bracelets. The 3-lug case design will make this a challenge.

All told, I’m happy to have this Seiko clean and running. This will be a nice 1980s-era piece to wear when playing games on the Atari 2600 or watching Stranger Things.