Thursday, March 12, 2015

Comtoise Clock Restoration - Part 2 (Various Repairs)

This will be a long post with LOTS of photos. I will try to divide it into sections as best as I can.


The brass front was one of my main concerns, and I began working on it almost immediately. I used a soft piece of leather, as well as hand pressure (the more you can repair with your fingers, the better) as well as various wooden tools. Items used were mainly popsickle sticks, and paint brush ends. Use a smoothing/rubbing action, and light pressure. You may need to work mainly from the back, but also from the front.

After about 45 minutes, I had this:

I went back to it a few more times to tweak more small details. Because it's such a busy pattern,it helps to hide a lot of the imperfections. Very tricky areas tend to be large flat spots and gentle curves.

The bob "as received". It doesn't look too bad in the photos, but it had several bumps around the edges, and the rays coming out from the ends of the hair were really buckled outwards compared to the rest.

The back on the bob, as well as the front brass dial surround are crimped in place. The crimping was very carefully lifted a little at a time, and as little as possible until the bob came apart.

I was surprised to see that the bob was actually made of three pieces, rather than just two. I had expected just a front and back, but there is also a steel dished front piece. It doesn't actually support or make contact with the front, so I assume it's merely for added weight and rigidity.

When I took this apart, I thought that this arrangement was odd, because the rod can't be pulled out from the top of the bob. I later found out that this might be a later repair, since normally the rods simply continue (as a flat bar) right into the rating nut.

After. Not perfect, but much better.


Parts before stripping:

Parts during stripping. I expected the paint to be very difficult to remove, but it came off very easily. You can see that I had plastic wrap over the stripper (because I thought it might need to sit and work for a while), but I didn't even need it.

After stripping. Note that the bell looked quite good in the 'before' photos, but it was spray painted silver, and hiding lots of rust.

Following the stripping, the steel frame parts were given a good soaking and scrubbing in a muriatic acid bath. This is the first time I used full strength (32%) muriatic acid (hydrochloric acid) for rust removal. This is definitely something you must do outdoors, with heavy duty rubber gloves, eye protection, and a breathing mask. I did not soak the parts excessively long, but I removed about 90-95% of the rust. Some of the remainder was sanded off with fine sand paper. The bell and the bell stand were some of the worst pieces, along with the top and bottom frame plates.


The tabs for the door hinges and front panel were repaired, but I decided not to do the ones on the back panel because they might interfere with the action of the doors.

To make these repairs, I used pieces of spring steel (metal strapping or old clock springs make good material for this). Ideally you should use a strong "springy" steel since it will be strong. Mild steel may wear quickly or bend too easily.

I started by cutting simple rectangular sections, polishing the face to bright steel, and doing the same on the panels. It's CRUCIAL that you have clean bare metal.

Silver solder was used for a very strong repair. The plate was heated to red hot, and soldered leaving the rectangular tab sticking out a bit. The actual tiny tab was filed to shape after.

The first one gave me the most trouble, because I had not cleaned a large enough area on the plate, and I didn't have quite enough heat.

The next 3 turned out beautifully. You can see 2 blanks in the bottom of the photo.

Another "repair" was to darken some bright silver screws. These two screws held the back panel in place, and they are later replacements. They don't really show, but I did not like the bright shiny silver look, and I preferred not to paint them. I immediately reached for gun blue, but it had no effect on the metal. As it turns out, these were stainless steel.

Stainless steel can be tricky to colour/darken, but my friend Jim suggested that I might be able to heat it to red hot, and leave it cool. This turned out working fairly well. Not a perfect black or deep blue, but a dark grey, which is fine. You can see a before/after here:


The dial on this clock was surprisingly flimsy and fragile. I had expected a very hard and solid dial, but these were enameled onto very thin copper. Most of the strength is in the actual coating of enamel (fused glass). On this clock, there are 2 or 3 blows to the dial which have caused minimal damage to the front in the form of small chips and cracks, but on the back, several sections of the enamel have broken away.

In addition to this, the top mounting hole has been completely torn away.

Here are 2 photos of the dial 'before'. Most of the damage is to the centre hole, and the top mounting hole.

The first cleaning trick to try on enamel dials is a good bath in Polydent. You'll want to find a suitable container, and use multiple tablets. For a bath this size, 2 or 3 should be enough. The Polydent will help to pull dirt from the fine cracks. If your dial is a Vienna dial, however, you may want to take more care since the signatures on Vienna dials are not fired into the enamel like this one.

To repair the torn hole, I used thin brass shim stock, and JB Weld. It would be easy to solder brass and copper together, but the heat would destroy the enamel.

JB Weld was also used to fill-in the missing chunks of enamel on the back of the dial. JB Weld dries exceptionally hard, and should provide some much needed strength to the damaged areas. It also happens to match the uneven grey tones on the back, but it could also be painted if necessary.

Following this, the areas to be repaired were filled-in, then painted with white oil paint. The white is not an exact match, but most of these areas will not be seen.

The rest of the repairs were pretty straightforward. The panels and frame were painted gloss black, the bell was given a clear coat, and all the parts were cleaned and oiled.

Here were a few photos during the testing phase.

Other repairs I didn't mention included things like making new leather washers for the bell, repairing a worn out screw on the pendulum guide piece, scraping off the solder from the canon wheel and brass disc, lightly curving the hands to conform better to the dial, etc. I still need to acid-was the hammer (I forgot to do it), and for the hands, I would like to replace that hex nut (not original) with a traditional square nut. I also need to make a toothed brass disc to hide the square hour hand locking nut. I plan to get proper rope "washers" (or make some) for the weight lines, and fix the short pendulum rod (4" short). The clock will need a wooden wall shelf.

Final photos and interior mechanism details in Part 3.

No comments:

Post a Comment