Other PW Stabilizing porcelain dial cracks

[rstl99]

I recently acquired an old French pocket watch which, based on its size, probably dates from late 18th century. The watch is complete with silver case but will need a restoration.

The dial of the watch is noticeably cracked but I don't see any of the chips missing. I'd like to clean it as much as possible (to get rid of some of the accumulated dark dirt in the cracks) and then stabilize the cracks by applying some kind of clear coat that will prevent any of the chips from coming off, or further cracking to occur. My understanding is that the lettering and chapter numbers are painted onto these dials, so cleaning by soaking in some products may not be a good thing.

Any ideas or suggestions? Thanks.

 

[model1857guy]

I'm afraid I don't have an answer but I'll be watching to see what people say as i have a similar situation.

On later dials I've run them through my ultrasonic cleaner, but as you said that isn't an option for a painted dial.

 

[Skutt50]

It is hard to tell without holding the dial but it is likely that the black paint is made from an enembel type paint.
In my experience the hand painting is linked to how the numbers were created. This however does not always mean that it will come loose easily.
I have cleaned several hand painted dials in ultrasonic solutions and not had any problems.
I check this by looking at the dial with a good magnifier to see if the numbers stand out or seem to melt in with the rest of the dial.
Before I clean I also test to scrape off the black paint in an "unconspicious" area. If it doesn't come off, I go ahead and clean.
(It is not often I have found a dial with paint that comes loose but is has happened. This was however on cheaper Swiss cylinder watch dials with printed numbers.)

Most of your cracks will be almost unnoticable after cleaning. There is a possibility you may have a chip come loose about 9 o'clock.

I like your idea of sealing the dial afterwards. I have had the same thoughts but never gotten around to test it. My main goal would be to avoid future dirt to enter the cracks but I don't know if it would make make the dial any stronger. Perhaps a clear coating used for car paint would do the trick. Just make sure it is ultraviolet proof!

 

[gmorse]

Hi Robert,

...Most of your cracks will be almost unnoticable after cleaning...

I usually soak these enamel dials, (they're enamelled glass on copper by the way, there are very few true porcelain dials), in a denture cleaner, which does as Skutt says and reduces the appearance of the hairline cracks considerably. I would be cautious about using an ultrasonic because of the risk of loose areas becoming detached. The numerals are almost always baked in as one of the later stages of the enamelling process, although signatures for vendors may be a different matter and should be carefully checked.

A coat of a transparent spray lacquer will stabilise the dial if it's in a really poor state, but the surface appearance will be altered. Missing areas of enamel can be touched in beforehand, either with tinted epoxy resin or artist's acrylic paint, which latter has the advantage of being easily reversible if the result isn't acceptable.

Regards,

Graham

 

[rstl99]

As always, thank you for the excellent advice.
. I don't own an ultrasonic bath so that rules out that approach.
. I like the denture cleaner solution, which I've read about in the past (hanging the dial in the solution with a thin wire).
. I had thought of transparent spray lacquer so am glad to hear this is an approach that can be used in some cases.
. I've used epoxy resin tinted with white paint before, to fill in missing areas on the edge of a dial. Gave a reasonably good result, though getting it smooth and even can be a challenge. Artist's acrylic paint sounds good, and I'll try that next time.
. Indeed, I mis-wrote in referring to this dial as "porcelain".
. I'll need to pay particular attention to the fragility of the signature, which is the reason I wish to preserve this dial.
Cheers.

 

[rstl99]

With the tip of an exacto knife, and while looking at it through a microscope, I gently scratched at the end of one of the minute markers (line) and the paint seemed to be flaking off under the knife. I'm thinking that means that perhaps the chapter ring and maker name on this dial were painted on AFTER baking? In which case I'd be leery of dipping the dial in Polident or any other agressive cleaner... Maybe I'll just gentle brush the hairline cracks with a very small and fine micro-brush, with some warm soapy water, and try to clean up some of the dirt in there (while not loosening off some of the chips of enamel).

I like these restoration tasks, but there is a lot to learn.

 

[Tom Huber]

Do not use an ultrasonic cleaner. The vibration can lift the enamel and leave you with a pile of enamel pieces.

Soak the dial in an ammonia solution or use the denture cleaner

Tom

 

[rstl99]

Wow, I've found all kinds of interesting solutions by querying historical posts here (and elsewhere).
ANyway, I'll give a try to the denture cleaner, and do a quick test before on another dial from similar era.
I wouldn't want to ruin the dial on this watch signed "Lépine à Paris", because I obviously could not get a replacement one (as can more commonly be found for a Waltham or Elgin or nameless European watch).
I'll report back how I make out. Thanks again.

 

[Tom Huber]

Do not ever attempt to soak a metal dial

Tom

 

[HUDD]

As always, thank you for the excellent advice.
. I don't own an ultrasonic bath so that rules out that approach.
. I like the denture cleaner solution, which I've read about in the past (hanging the dial in the solution with a thin wire).
. I had thought of transparent spray lacquer so am glad to hear this is an approach that can be used in some cases.
. I've used epoxy resin tinted with white paint before, to fill in missing areas on the edge of a dial. Gave a reasonably good result, though getting it smooth and even can be a challenge. Artist's acrylic paint sounds good, and I'll try that next time.
. Indeed, I mis-wrote in referring to this dial as "porcelain".
. I'll need to pay particular attention to the fragility of the signature, which is the reason I wish to preserve this dial.
Cheers.

For dial repair I've used "Milliput Superfine White". This is a two part white epoxy which you can apply and then manipulate for quite a while to get a smooth level finish. You can tint it as you describe and try to get as good a colour match as possible, and you can when set fine polish. I have used this on damaged dials to improve stability of the glass and prevent further loss. Hudd