The following article appeared in International Wrist Watch Magazine, 1998 Issue
Number 35. It generated a lot of interest and good comments. Since it demonstrates
the kinds of services I offer, I thought it was worthwhile to put on my site. Other
articles that I've written for this magazine are:
1996 Number 30, How A Watch Works: An overview of the fundamentals of the watch mechanism.
1997 Number 33, Chronograph Basics: An introduction to popular vintage chronograph
1997-98 Number 34, Watch Cleaning Practices: The different methods, showing not all
'cleanings' are alike.
1998, Number 36, Rolex Automatics: The evolution of the 'Perpetual' movement, from
the 1930's to the 1970's.
1998, Number 37, Watch Maintenance: Why regular servicing is necessary, what parts
wear out, etc.
2000, Number 41, Collecting Vintage Watches: A good primer for the new collector
on commonly available watches, showing which brands are the best value, etc.
Most of my recent articles are on my line of Thomas Gref watches. Contact International
Wrist Watch Magazine at www.iwmagazine.com
Restoring a Gruen Curvex
Copyright 1997, Tom Gref
Most people probably do not know what is involved in repairing and restoring a typical
vintage wristwatch. I thought it would be interesting and educational to describe
this process from start to finish, in both words and photographs.
I selected this gold-filled 1940’s Gruen Curvex as a typical example of a non-complicated
watch restoration. It has the popular 17 jewel Gruen 440 caliber movement, measuring
8 3/4 lignes by 9 3/4 lignes. This watch, in particular, had may common ailments
and therefore helps illustrate many of the common solutions.
The watch, as received, is shown. There are a number of different things that I look
at when evaluating such a piece, including both aesthetic and functional details.
The case was dirty, but was in good condition without dents or worn spots. The dial
was in poor original condition. It had darkened and aged unevenly, which made it
difficult to read. Also, the hour hand was broken and the crystal was missing. I
knew from experience that the hands were not original, as they should be leaf-shaped,
so I hoped to be able to find some correct replacements.
I am frequently asked if discolored dials (like this one) can be cleaned, and this
answer in almost all cases is ‘no’. Generally, dials are made of silver-plated brass.
The minute track is painted on using a stamping process, and then the entire dial
is lacquered with a thin clear-coat to prevent it from tarnishing. Raised gold numbers
are either stamped in from the back, or they are separate pieces applied (pinned)
to the dial. In most all cases when a dial appears to be dirty, it is really an indication
of lacquer which has discolored and/or fallen off. This then allows the underlying
silver surface to tarnish. The only remedy is to refinish the dial.
After reviewing the aesthetics, I moved on to examine the mechanics. I always try
to wind and set the watch first, as this is a common source of problems. I check
to see that it winds smoothly without skipping or scratching, also noting if there
is noticeable tension from the mainspring. Obviously, no winding resistance indicates
that the mainspring is broken or that the gears have come out of mesh. I also check
for wear in the mechanism by looking at the side to side play of the crown (that
is, wiggling it from 6 o’clock to 12 o’clock). This indicates either a worn stem,
a worn winding hole in the watch plates, or both. This watch had a worn stem.
I then pull the crown out to check the setting functions, making sure that the crown
clicks properly between the two positions. A weak snap action usually indicates a
broken set bridge. Finally, I check to make sure that there is proper tension when
setting the hands. Hands which set too easily can be a problem, as the resistance
you feel is the coupling force between the movement and the hands. A weak resistance
here indicates a weak coupling, so the movement could be keeping perfect time but
not driving the hands properly, giving the indication of a substantial loss of time.
Therefore, from my initial evaluation, I knew primarily what would be necessary to
fully restore this watch. This includes: overhauling the movement, replacing the
worn stem, finding a new set of hands and a crystal, and refinishing the dial. The
customer also wanted a new crocodile band.
I knew that finding an original pair of hands for this caliber would be difficult,
so I chose to locate those first. Because there are so many variations, hands are
more difficult to find and fit than most people think,. They must be ordered by specifying
the caliber of the movement (Gruen 440), the shape (leaf-shaped was most common on
Curvex watches), the color (yellow - white and blue would be other common possibilities)
and the length (in millimeters). The closest I could get to an exact match was a
pair of properly sized blued steel hands. The blue color (caused by heat treating
the steel) can be removed using an acid solution, resulting in a shiny steel finish.
I sent the hands, along with the dial, to the dial refinisher with instructions to
plate the hands gold. This would be a correct solution, as the hands were originally
gold-plated. Although this process was a bit indirect, it did yield good results.
I then proceeded to find a suitable crystal. It is necessary to first measure the
case to determine the correct maximum length and width of the crystal using vernier
calipers. I wanted a curved cylinder crystal, which would be fairly bold looking
and would accentuate the curve of the watch. I also prefer glass crystals over plastic
because of their clarity and scratch resistance, so I went to my 1960 s vintage
BB glass crystal catalog. The catalogs are arranged by size and shape, and usually
give an indication of the watch manufacturer. It is helpful to have some old catalogs,
as many of the older crystals are deleted from the newer catalogs. I was able to
locate the proper part number/crystal, and ordered it from my supplier.
I then proceeded to disassemble and clean the movement (Figure 5). I always completely
disassemble the movement before cleaning to get the best results possible (some watchmakers
leave the movement wholly or partially assembled to save time.) The movement is cleaned
in a purpose-built ultrasonic cleaner using special petroleum-based cleaning solutions.
It is basically an automated 4-station process, with one cleaning, 2 rinses, and
a heated drying. Overhauling the movement was fairly routine, and after cleaning,
lubricating with synthetic oils, and adjusting it ran quite well. It needed some
minor (and routine) adjustments to the hairspring.The case was then cleaned in an
ultrasonic tank cleaner using a water-based solution. I polished it using a 2 step
process on a standard jewelers polisher. I cut the stem to length and re-used the
original signed crown, cemented the crystal, and reassembled the watch.
I hope that this has given you some idea of the steps and work involved in restoring
a vintage watch. This example illustrates many of the common ailments, and therefore
much of this information can be applied to other watches. The watch is now in good
running condition and is ready to wear and be enjoyed by its owner.
Tom Gref - PO Box 69151 - Tucson, AZ - 85737 - 520.818.3382