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  • Graham Powis Member of the British Horological

Longcase Clock Repair, a conservation approach,


There is much more to the repair and conservation/restoration of a Longcase Clock than you might at first consider. In the 17th and 18th centuries many beautiful clocks were made up and down the Country. There were Clockmakers in the big towns and Cities, London arguably producing some of the finest examples. Let us not forget however that Thomas Tompion's right hand man was a Cumbrian, George Graham. Sticking to the subject there are many regional variations found in Longcase Clocks notably in the striking mechanism.

For the Horologist today the challenge is having the knowledge to work of the different types of mechanism that are met with.

For me the movement of a Longcase clock is the most beautiful of mechanical things. How many machines do you know are still working after 200 years of almost constant use and still working properly? When a Longcase Clock comes into the Workshop for repair much more consideration is given to it than to merely get it working again. When the clock movement is dismantled into its component form it will often give us much information about its past. Only recently I found 'Henry Phillpson Jnr- Ulverston' 1836 beautifully signed on a clock plate. Phillipson was the last of the line of the Barber of Winster dynasty and almost certainly was trained by Jonas Barber himself. This significantly adds to the historical interest of the clock.

Back in the early days of clock making Clockmakers' sought quality brass plate from which to produce the plates and wheels needed to make the clock mechanism. Back then the manufacture of brass was a very different process to the one used today. The molten alloy {approx 70% copper & 30% zinc} was floated across a shallow moulding tray and allowed to cool. The brass back then was cast as opposed to the brass made in modern foundries produced in huge rolling mills to make brass sheet.. The old cast brass invariably had imperfections in the metal which were there because of the inconsistent cooling of the brass sheet; not unlike old window glass. I often have clocks over 250 years old passing through the Workshop, it is imperative that they are treated with care when going through the workshop processes before being returned to a Client.

Today there are commercially available clock cleaning fluids available to the horologist, These fluids often have a very high ammonia content and are sometimes used in conjunction with an ultrasonic process. This procedure must NOT be used on old clocks made of cast brass. Serious damage can occur if old clocks are cleaned in ammoniated cleaning fluids. The ammonia has an adverse effect on the copper content of the brass and finds its way deep into the metal along the imperfections found in the alloy. This reaction is made worse by ultrasonics because the action of the tank {cavitation} serves to make matters worse

Above you can clearly see a crack that has formed in the brass plate, in this case it's across the pivot hole of the warning wheel {front}. The clock has also lost its lovely golden lustre associated with these old clocks, this is because the chemicals have bleached and etched the surface of the metal. The other problem is the lubrication needed to lubricate this pivot will tend to leach away into the crack.

This adverse phenomena is known as 'STRESS CORROSION CRACKING. Have a look at another picture of the same Longcase Clock movement.

This is the end of the escape wheel {the last wheel in the going train} You can see a darker patch around the pivot. This is where I've applied oil and it has leached into the clock plate like a sponge. Not to put too fine a point on it this clock movement has been previously cleaned in an ammoniated cleaner and in effect has been ruined. You can see the pivot hole has worn due to its inability to hold that all important reservoir of oil needed to lubricate this part of the clock. Don't get me wrong ammoniated cleaners have their place, they are fine when cleaning the component parts of modern brass clocks. They must not be used on old clockwork however. Why has this happened? Ignorance or laziness on the repairers part, plus the fact that cleaning the clock using 'conservation methods takes much longer!

Remember me telling you earlier about the signatures that can be found on Longcase Clocks, here's another example I found recently " W Burton, Kendal; 1811. Harsh cleaning will rub out this signature, surely this mark must be preserved!

Metal polish's abrasive effect will rub out etchings on the metal, overly shiny Longcase clock movements are scorned upon in conservator's circles.

When we admire the lovely patina of an 18th century clock case should we see a gleaming clock mechanism when the hood is removed?

It is important that the working surfaces of the mechanism are friction free but a Longcase Clock movement should not have an over polished look to it. Sorry that you had to endure my rant I will now go through the repair of a Longcase Clock using a conservation approach.

Henry Jones of Chalford-Gloucestershire, C:1780.

Here is a 8 day longcase movement made by the above, this clock hasn't received any attention for around four decades.

When we consider how long this old clock has been working without any attention it is testimony to the skill of the maker that it can be made to work properly again. Correct and clean lubrication for clockwork is essential, it's unlikely that there will be any effective oil left within the workings of this old clock at all. Add to that the accumulation of dirt that has built up over time; the clock will certainly need some attention. This clock will be completely dismantled, then cleaned using a conservation method approach; its wear issues will also be addressed.

Pictured below the clock is shown exactly as was when dismantled, great care will be exercised in the cleaning and repair of the clock, the wrong cleaning process could completly ruin a Longcase Clock mechanism as mentioned at the beginning of this post.

So, at Cumbria Clocks a conservation approach is always used, we do not use commercially available ammoniated clock cleaning fluid to clean the components of antique clockwork. ..

An 18th century clock case will no doubt have nice patination, when the hood is removed do we expect to see a mechanism like a 'glowing orb'? This particular movement is well over 200 years old, surely the last thing wanted is a clock mechanism that looks new.

Recently an old 30 hour country clock was brought to the workshop because the winding pulley had seized. The first thing noted was how shiny the clock mechanism was. A closer look revealed that the the clockmaker's original 'marking out had been partially rubbed away and previous repairers etched sinatures had suffered also. It turns out the the clock had been polished with Brasso. When dismantled the clock I cleaned it using the conservation approach. There was a lot of residual polish still in evidence, Brasso & Oil=grinding paste. I cannot reverse that fact that this clock has been over cleaned however it now runs properly again..

The cleaning process of a Longcase Clock can involve metal polish but the detritus present must be loosened prior to its use and it must be completely removed prior to reassembly, Using 'elbow grease' with a metal polish can easily erode the original character of the clock away

In the above picture we can also see a previous repairers attitude to tidy work, in the top right hand of the picture what looks like a panel pin has been utilised to fasten the clock plates together. Proper taper pins are the only acceptable method of reassembling an antique clock.

Having cleaned the clock using proper conservation methods the clock has been laid out in component form for your inspection. The cleaning fluid I use is always filthy after use and is only used once, often the clock has a coating of tobacco which doesn't smell particularly nice during cleaning. The cleaning process used at Cumbria Clocks removes all surface grime.

The clock parts are now ;Horologically clean', after the non aggressive ultrasonic process the clock is rinsed several times. It is imperative that this is done properly. Oil will readily emulsify if it mixes with soaps and detergents. The parts will now be individually finished by hand prior to reassembly.

Had you been looking at a clock cleaned in ammoniated fluid it would certainly have looked much shinier. Brighteners are added to the ammoniated fluids but, the fact is the clock has been effectively bleached clean, you wouldn't boil wash your Cashmere Jumper would you?

A very important process that is often overlooked is pivot polishing, we always refinish the pivots of a clock; equally the pivot holes will be 'peg polished' also. You can obtain details about pivot polishing in the Workshop section of the main website.

To conclude, here is the finished clock movement, all that remains to be done now is affix the seat board and fit some new traditional gut weight lines. The clock has been lubricated with the finest horological oils available and will be tested for a period of 14 days.

The clock will be returned to its owner and set up within its clock case, this is all a part of our service.

If you are thinking of having your clock serviced/overhauled ask the clock repair shop what method of cleaning is used? if ammoniated cleaning fluids are mentioned remember the key points mentioned in this blog, hopefully from that you can make an informed decision.


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