Adjusting an Unadjusted Gruen N510 Wristwatch, Part 2: Restoring the Dial & Case

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Some time back, we serviced and adjusted a Gruen N510. The Internet is stuffed with Gruen fans, apparently, because that post is in this blog’s Top 10 all-time posts. Who knew? So for all you Gruen lovers out there, this Part 2 is for you.

The 510 movement cleaned up nicely, but the dial and case looked wretched. It’s time to get the watch ready for the wrist.

Dealing with the Dial

This Gruen’s dial was grim, blotchy, and nasty. Gruen was a leader in quirky, off-beat designs, and this dial is one of their nicer designs. It should have a shiny, mirror-polished gold ring around the edge. The center is also gold-colored, but it has a satin, brushed look. The divots in the dial serve as hour markers.

It’s a clever design because it maintains legibility despite the dial, case, and hands all being gold. The recessed markers throw shadows that stand out against the gold outer ring, and the gold hands stand out sharply against the brushed inner circle.

Some collectors are purists about original dials, and I respect that. For work watches, like diving and aviation watches, a battered dial suits the piece well. But for a gold-colored dial in a gold dress watch, a blotchy dial looks sad and defeated—a good metaphor for one’s soul-crushing cubicle job, perhaps, but not a watch you’d want to wear to that job.

I sent this off to International Dial Company, which has done a lot of good dials for me over the years. For this dial, they offered a more expensive “exact match” restoration or a cheaper “close enough” restoration. Being cheap in all matters Gruen-related, I went for the cheaper option.

Around a month later, the dial looked like this.

I’m pretty happy with it—it is vastly improved. Indeed, I wonder that the “exact match” dial would look like if this is the cheap version.

Cleaning and Polishing the Gold-Filled Case

With the dial sorted, it’s time to clean and polish the case.

The top half of the case is gold-filled, much like the cases of most of the pocket watches we work on. Gold-filled cases have a thick, solid layer of gold fused to the underlying base metal. It is much more durable than gold plating, but the gold layer will wear off over time.

This watch was probably a drawer denizen—it has extensive wear on the lugs, sides, and top, like it was rattling around in a plastic bag filled with other watches for a couple decades before being released into eBay.

The worst part is the right side, where the crown goes. The darker base-metal layer contrasts badly with the yellow gold layer.

Short of replating the case, there isn’t much one can do for a worn-down gold-filled case. Your best bet is to make both materials—the base substrate and gold coating—similar in glossiness. The human eye is drawn to glossy things, and it is harder to discern color differences between two shiny things. (Trust me on this one—it is my day job.)

To shine up the case, we turn to the polishing lathe. For gold-filled cases, we don’t want anything especially coarse. I started with the Menzerna yellow compound with a loose cotton wheel.

After a bit of polishing, the case got cleaned in the ultrasonic, dried, and then polished with a final finishing compound. For an ultra-fine finish on yellow gold, you can’t beat Menzerna’s M5 white compound. (If you don’t use Menzerna compounds, you can buy cheap sample bars that will last you forever at Cousins UK.)

Note that it’s a good idea to keep wheels and compounds of different grits sealed in bags so they don’t get contaminated by each other or from the general dust and debris of a polishing workspace.

I dare say, the case turned out well. You can still see the difference in plating on the case top near the crown hole, especially when magnified, but the shiny brass base layer is roughly the same color as the gold outer layer.

It won’t look this good forever—gold is less reactive than brass, so it will stay shiny while the brass slowly tarnishes—but that’s something to worry about later.

Polishing the Steel Case Back

The case back is stainless steel and a common Gruen design. The back snaps on to the front, and it has two polished surfaces. The outer ring should be mirror polished, and the inner ring has a straight, linear grain.

In our watch, both surfaces look scuffed and dull.

Here’s the “after” pic.

I have a post planned for polishing this kind of case back, but it is an easy process. You first polish the entire case back, using the usual wheels and compounds for getting a mirror polish on steel. The the case is pulled along emery paper, using some sort of straight edge or jig as a guide.

Final Touches

And now the stem and crown. The movement was gunky and rusty, including the stem. This stem can’t be saved, and the crown is worn down to a smooth surface that is hard to grip.

Fortunately, the fates above smiled upon my humble efforts and put a huge stash of Gruen stems for sale on Ebay for a good price.

You can buy individual crowns at watch-part stores, but it’s better to snatch big lots of crowns on eBay when they come up. I have a large stash of vintage ones and a tidy pile of newer ones. They’re a mish-mash of crown styles and sizes, but there’s usually one that fits.

With some sorting and sifting, I found a replacement. The new crown is bigger and knurled, so it will be easier to grab and turn than the old smooth crown.

When installing a vintage or new-old-stock crown, don’t forget to clean and polish it—a glossy case with a tarnished crown looks bad.

To literally top it off, I installed a high-dome plastic crystal—30.20 mm in size, if you’re working on one of these. This might seem like a thin watch, but the hands stick way up there.

Wrapping It Up

And there we have it! With a coffee-colored ostrich band, this watch is looking sharp.

This will be a great watch to wear on those days when you think, “You know, I think we need some more yellow to go with our yellow-on-yellow.”

When you see the watch in this state, you can see why Gruen watches have so many fans. In their day, Gruen was in the sweet spot for value and quality and made some fun and edgy designs. More yellow!