Most of the forum members might have tried this but for those who haven't this is the easiest way to restore a dial.
The dial which I have on a old cal 231 has turned very dark due to the organic lacquer aging, The dial was unreadable really, I know the purist might be against this but the dial was really too dark. Now it is very crisp and clear.
All I did is> Put lemon juice in a small container of water, 4 parts water to one part lemon juice and leave the dial for ten minutes keeping a eye on it and swishing the mixture round while you wait. Be careful not to leave it to long. I then removed the dial from the mixture and then with a very soft artists paint brush with plenty of water on it I ran it over the dial very gently removing the remainder of the old lacquer. This technique doesn't work on modern dials though. After the lacquer has been removed I rinsed the dial under a slow running tap. Distilled water is probably best used in all of this process but I didn't have any.
If you are not confident I would practice on a few old dials you might have that are of no use.
Cheers Mick

 

So you strip the bad lacquer off it - great. Now what happens in a year or two when there's no protective coating? Well, I'll tell you (because I tried this on a Benrus Dial-O-Rama): it tarnished all over again in that short period of time. But now there's no coating to tarnish, it's the paint. Unless you can recoat it, this is a VERY temporary job.

 

I will now send the dial to David Bill and sons for new lacquer to be applied, the last time I did this it was around £30 so not too expensive.
Cheers Mick

 

Good old Yorkshire tap water is what I used today.
Cheers Mick

 

Ahh, a key piece of information. Thank you.

 

Yorkshire Gold?

 

As long as a sheep hasn't died further up steam it is.
Cheers Mick

 

BTW, here's a link to a conversation on a Hamilton forum wherein a guy suggests a cleaning process using ammonia...

http://vintagewatchforums.com/viewtopic.php?f=8&t=550

 

the laquer is not that difficult to apply..... dry it carefully with a hair dryer. wait another day. rest the dial on something that is higher than the dial feet to have it straigt. have a tea cup ready. use a spray can with polyurethane based matt laquer in heavy duty quality. indoor use stuff is fine. shake it for a long time. spray in a way, that you have it 20 cm above your dial in a sweeping motion, that only residue gets to the dial surface. never straight on the dial. cup over the dial to avoid lints or dust. dry it for a few hours under the cup. do the same procedure at least one more time. patience is required, but it works. if the dial was not `100% dry, it will tarnish under the laquer again. some practice on old surfaces might help. kind regards. achim

 

I might give this a go Achim, thank you for the info.

 

I just thought lemon juice = citric acid. Of course. I use citric acid to remove rust from parts; say, a stem. Give it a soak in a solution and it's quite amazing how well it works. Citric acid is available on eBay for very low prices; of course, you might have a lemon at hand, in which case, no need. But of course if you have some good ol' C6H8O7 around, you can mix up as much or as little as you like – and stay away from domestic strife, too.