Minimal Invasive intervention – repair, restore or conserve?

Minimal invasive intervention is a term which means, how far do you go to repair, restore or conserve a clock without changing it in a significant way? Minimal invasive intervention is a “borrowed” term from a clock forum site that I frequent. Some would say that any work done on an antique clock detracts from it’s value, like putting new fenders on an antique car. Nice looking, but less desirable.

At the end of this article I have a number of questions the reader (collector) might consider.

When does performing too much work on a clock affect it’s collector value? If you go too far does it lose it’s attraction as a collector item. A true collector is more interested in a movement that has never been worked on, than one that has been repaired or restored. But just how far do you go with a non-working vintage or antique clock? While it is always desirable to have a running clock most understand that to make a movement actually work, some invasive intervention has to be accepted such as bushing and pivot reconstruction.

Repair implies rectifying the faults or poor servicing of a clock in a significant way which might alter it from it’s original form.

Restoration involves the reconstruction, in some cases, of the movement or the clock case to a “as new” condition.

Conservation involves the protection and restoration of a clock using any methods that prove effective in keeping that article in as close to its original condition as possible for as long as possible.

Some amount of intervention is not only necessary but desired by some collectors.

Let me illustrate my point. In the photo below we have an antique American 1878 Ingraham Huron time and strike shelf clock.

RS April 12th
Ingraham Huron shelf clock circa 1878

The uniquely designed rosewood case is in excellent condition for a 138 year old clock and is a real conversation piece. The clock hands are original as is the pendulum, sash and bezel hardware. Everything about the case is original! It has no breaks, cracks or missing pieces. The case was cleaned with Murphy’s Soap and water and followed by a light application of shellac. There is a buildup of grime as one would expect on the clock face which some might feel detracts from it’s appearance though it contributes to it’s character. That I will not touch.

The movement is original but not well repaired. One can only imagine that in small town Nova Scotia, folks did not have access to professional clock repairers and relied on the community tinkerer to get their clocks running. In those days a clock was simply an appliance and the objective was to get a broken clock running again quickly and at a minimal cost. Consequently some questionable methods were used to get the clock running again. There is plenty of solder on the movement and re-alignment of some gears (new pivot holes were drilled into the plates). The soldering was likely in the 1940s, when soldering guns became commercially available.

This clock will run for about 2-3 days on a full wind and then stop. Nudging the pendulum will get it going again but it stops after an hour or two. Looking at the front plate, there is little to indicate that there are issues with this clock. Once the movement is out of its case issues begin to surface. The next two photos shows invasive repairs made to the clock.

RS Ingraham movement (2)
This lantern pinion has plenty of solder

I brought my Ingraham to a certified horologist and we had a long discussion about what direction we should take with this clock. Do we repair, restore or conserve? He told me about a customer who came in with a kitchen clock (AKA Gingerbread clock), a family keepsake they wanted running again. Kitchen clocks are very common today because thousands were made back in the day. There are very few of any real value but a clock that has sentimental value is always worth repairing. He will repair most of them to the customer’s satisfaction but he recommends that if the movement is beyond repair that it be replaced with a period correct movement. His customers accept this as an option, however, a clock with a replacement movement has little or no value to a collector. He agrees that my Ingraham Huron mantel clock is a good example of a clock where the movement should not be replaced, instead, restoring it to it’s original state.

RS Ingraham movement (4)
Piece added to the plate, second arrow shows new pivot hole.

Collectors are always looking for a completely untouched clock but an antique clock in pristine condition that has never been meddled with is a rare find. Using this clock as an example, a repair might take away from the value of the clock while restoration might increase it’s desirability (and value).

Here are some questions that I would consider when making a decision about any newly acquired antique or vintage clock that requires intervention.

  • Is undoing the “damage” caused by a previous poor repair defined as an overly invasive procedure?
  • If the repair was done shortly after the clock was made, it was a proper repair and was clearly documented as markings inside the clock case should it be left untouched?
  • Is the poor repair part of it’s historical provenance and should the clock be left as-is?
  • Would bringing the movement back to it’s original state be considered a restoration or a repair?
  • In the case of the above clock, does eliminating all of the solder qualify as a minimal invasive intervention?
  • Will a repair enhance or decrease the value of the clock?
  • Would not doing the repair / restoration be considered conservation?

In my view conservation is minimal invasive intervention. Repair and restoration are considered more invasive. Let me know what you think.


4 thoughts on “Minimal Invasive intervention – repair, restore or conserve?

  1. Ron,

    As usual, you’re getting a rather long comment from me. 🙂

    This is a great article, but I feel that the rather quick descriptions really don’t emphasize some of the key points about renovation (restoration) vs preservation vs conservation. Conservation has very strict guidelines that can be a real nightmare to work around, depending on the project. Conservation not only means using the same materials and methods as the original (to make any repairs) but it also means that none of the original surfaces of the object can be modified in any way. All repairs must also be completely reversible – even something as simple as a small paint touch-up, or a scratch in the finish.

    I know that in the UK, a Grade I listed building must be repaired using only authentic and original methods and materials to the period when the building was constructed. This might not sound too bad at first, but it can be a huge pain, and an exorbitant expense to any homeowners who end up purchasing a listed building. Any rotted beams (as an example) have to be replaced with hand hewn log beams of the correct size and wood species, which are probably close to 30x or more than the price of just buying some dimensional lumber. You also can’t add anything like pressure treated materials. Same with walls. Any wall repairs usually have to be made with hand mixed and applied horsehair plaster ($$$). I’ve watched several episodes of “Restoration Home” which is a UK series, and some of the restorations cost millions. To add to all this, all the repairs and materials have to be approved. If you want marble tiles in your kitchen, but it wasn’t available at the time, you can’t use it.

    This site has a pretty comprehensive (but not overly lengthy) breakdown of the categories:

    When I see big solder blobs like in your Huron movement, I will remove the soldered plates (and buff as much of it off the brass plate as possible), and on the wheel, I will remove the blobs and clean up the surfaces lightly (I do this in the lathe). It’s very hard to remove all of it, but I aim to improve the look without being excessively picky about it.

    As per your questions, here are my answers:
    – No
    – Yes (I am picturing hole-closing punch marks or hand made bushing in a longcase clock)
    – This is harder to picture. I would hardly consider keeping a poor repair “just because so-and-so” did it. I’ve seen horrifying repairs, like a coping saw blade as a suspension spring. If the “repair” was a replaced hand, or a replaced pendulum or weight (which is not excessive) then I would consider leaving it. If I removed the repair, I would keep the parts with the clock.
    – Both? Probably a restoration. In a lot of cases it’s not possible to completely return any movement to its original condition. Something like a dovetail tooth repair would mean replacing the entire wheel with a new one. The brass would also have to be custom cast to be exactly the same colour, etc. In the case of hole-closing punches, very large bushings would be required o completely remove the punch marks, etc. In general it is acceptable and desirable to return movement in as close to original condition as possible.
    – Yes. I would consider invasive to be replacing large elements. Removing “add-ons” is not invasive to the movement itself, because they are essentially separate components. An example of an invasive repair that could be essential, but that would be visible is replacing a badly damaged escape wheel bridge on an American movement. Most were a specific shape, and riveted in a specific place. It’s very rare that one would need to be replaced, but I have one clock in my collection where this was done, and it looks AWFUL. I plan to re-repair this and make a custom bridge of the correct shape and layout, and to fill the new rivet holes. This will be a very invasive repair, because the repair will have been done twice, but the final result will be “back to original” with “battle scars” left behind from the previous bad repair.
    – A well done repair will not devalue a clock. Generally the movement isn’t visible, and as long as it’s not a replacement movement, the value should not be affected much. In this particular case, the removal of the solder blobs, the patch plate, and plugging the extra hole would likely increase the value.
    – Yes, but considering that the clock does not currently work properly, and that the repairs are very unsightly, the conservation would not be adding to the value of the piece.

    I would love to hear your feedback regarding a similar situation with my John Birge column clock movement. This one was filled with AWFUL repairs.

    – Was the movement more valuable with the bad repairs, or after the repairs?
    – Did any of the old repairs have historic value or merit worth keeping?
    – Has the value of the movement been increased or decreased? Has it stayed the same?
    – Were these repairs minimally invasive, or very invasive? Some are more than others, discuss.
    – Should the old bent nails and wire pins have been kept? What about the replaced fan wheel? The repaired crutch wire (which was partially original – but keeping in mind that it’s fully visible through the dial)?
    – What about the solder on the locking plate?
    – Would it have been preferable to leave some of the bends and kinks in the strike wires?


    Liked by 1 person

    1. Hi JC. Thanks for your comments and thanks for answering my questions. You have given me food for thought. Yes, I could have written at length but in this world of soundbites, getting the message out as succinctly as possible supersedes an in-depth article but your point is well taken. I have gone to your January 2016 article on the Birge clock and will attempt to answer your questions in the next day or so.


  2. Interesting questions! It’s a very nuanced situation. Instead of answering your questions (which I’m going to think over) I’ll pose you a new one about my dream repair and maybe you can provide your opinion on how invasive it is. My dream is to be able to laser cut or 3d print parts to replace broken parts in a clock movement, instead of having to buy a whole other movement and scavenge parts. Imagine a movement that was completely defunct because of 2 missing/broken parts – now it has 2 3D modeled or laser cut parts to replace them and works like a charm. It’s repair, hopefully it doesn’t involve drilling any holes or in any other way damaging the movement as it was, and in a way it restores the clock to (a form of) its original condition. I’m aware that some horologists do this to various extents.

    This is what I really want to be able to do and hopefully given another year or so of learning, I’ll be able to. The 3D modeling part I’m ready for (I’m a mechanical engineer). I think it is not necessarily invasive, but it still would only appeal to a specific subset of collectors or buyers.

    To your questions, I’m going to think on them and get back to you!


    1. Thanks for commenting. Those who fix clocks often rely on donor parts. Case in point. I have a 114 year old Gustav Becker Vienna Regulator. When I got it, the movement was missing a star wheel. The star wheel is used to advance the strike. I sourced out a movement from Poland but had to ensure that the new donor movement was from the same factory (Braunau) and because the movements are numbered according to date of manufacture I had to get one as close to the time the original movement was was made in order that the star wheel would fit properly. Why, because there were subtle differences in the design of later star wheels. Even 114 years ago clocks were mass produced but there were occasional production changes, just like today. Now that the part is in the clock and if I decided to sell it, I would have to disclose that the movement is not totally original and that parts were sourced to get the clock to proper running order. The buyer would accept the repair if the parts were period-correct. If I were to put new 3D parts in a 114 year old clock I would be faced with an interesting dilemma.

      However, if the clock had sentimental value and was intended to be passed on to family members, a 3D repair would be a great option. If the clock were a common mantel, wall or shelf clock like a gingerbread for instance, the addition of 3D parts would not likely effect the value in my opinion. After-all buyers are always interested in a running clock even if some compromises had to be made.


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