Lead Weight Corrosion - How to Remove

[Dick C]

In the following thread with posts 51-61 there has been a discussion concluding as of today with my posting of the weight. This weight is lead that is wood encased and has corroded to the point that the wood has split.

The clocks of Charles Alvah Smith

The pallet assembly (Red Arrow) is mounted on a steel pin projecting forward from the back plate. The brass screw serves as a stop to keep the assembly from moving forward and helps to keep the escape wheel centered on the pallets (brass rollers). If your clock was running then this never needs...

mb.nawcc.org

Upon removing the outer portion of the wood encased lead pendulum what is shown is the significant corrosion. Now I understand that it is somewhat dangerous to inhale/injest the corroded material and I will be utilizing an industrial mask to do what is needed.

What are your suggestions as to what I might do to remedy the situation? If I cannot find anything I may have to resort to opening the bottom and replacing the weight.

Thanks,
Dick

 

[roughbarked]

Collections Online | British Museum

www.britishmuseum.org

Chemical Removal of Lead Corrosion Products

Restoration treatment, specimen preparation or mass loss measurements on coupons made of lead require a reliable process of dissolution of corrosion products. In this study, several types of model corrosion products with compositions representative of ...

www.ncbi.nlm.nih.gov

 

[R. Croswell]

Collections Online | British Museum

www.britishmuseum.org

Chemical Removal of Lead Corrosion Products

Restoration treatment, specimen preparation or mass loss measurements on coupons made of lead require a reliable process of dissolution of corrosion products. In this study, several types of model corrosion products with compositions representative of ...

www.ncbi.nlm.nih.gov

The referenced site is reporting an overload just now, but I would thing that a chemical method would require the lead to be removed from the bottom section, which I believe the OP did not want to do. I would think that a rasp and wire brush to keep the rasp from clogging should remove the corrosion. Collecting the debris will be creative. Perhaps a coat of lacquer afterwards to prevent future corrosion?

RC

 

[Uhralt]

It seems the lead corroded in places that touched the wood. I think there was a chemical reaction of some king between acids(tannins?) in the wood and the lead. Therefore, it is important to prevent direct contact between lead and wood in the future. Lacquering, as RC recommended, may work or wrapping the lead into plastic foil would also do the trick.

I believe that in addition to the corrosion of the lead shrinkage of the wood has also contributed to the split. It looks unlikely that the cleaned-up lead would fit into the opening after closing the split. Maybe it is necessary to add a strip of wood to make up for the shrinkage.

Uhralt

 

[Dick C]

The referenced site is reporting an overload just now, but I would thing that a chemical method would require the lead to be removed from the bottom section, which I believe the OP did not want to do. I would think that a rasp and wire brush to keep the rasp from clogging should remove the corrosion. Collecting the debris will be creative. Perhaps a coat of lacquer afterwards to prevent future corrosion?

RC

I have not found a way to remove the bottom at this time. It appears that the smaller bottom area might be a cap so will see if further examination allows me to remove the cap. I expect that there is another end of the rod which has a nut that when removed will make the complete unit accessible.

 

[shutterbug]

You might be able to screw the bottom out of the lead. Worth a try anyway. It looks like the wood split on you too. You'll have to prevent that from happening again when you re-pour the lead. A smaller container inside the wood would work, but you may end up with a lighter weight. Kind of a sticky wicket you have there.

 

[Dick C]

You might be able to screw the bottom out of the lead. Worth a try anyway. It looks like the wood split on you too. You'll have to prevent that from happening again when you re-pour the lead. A smaller container inside the wood would work, but you may end up with a lighter weight. Kind of a sticky wicket you have there.

Thought about the small container and the effect on weight. Might be able to offset the weight loss by using tungsten cylinders which are heavier, along with the lead....another possibility.

I haven't given up on removing the wood bottom...another alternative is to drill a hole in the bottom cap to see what is there. I did notice that in other clocks of this type by Charles that the bottom seemed to be open. Could not see what the inside of the hole looked like.

 

[Willie X]

The lead was probably cast in place and I doubt if you will ever remove it without opening up the wooden encasement.

After you get it removed, baking soda in warm water and a stiff brush will remove the oxide. Oil or grease will keep the oxidation away for a long time. You may be able to make a new case, or machine the old weight a bit, so it will slip into the old repaired case. That split will have to be closed with a snug fitting wooden strip.

I see three choices: Repair what you have as best you can. Make a completely new wooden weight shell and recast the lead weight. Or, leave it as is and pass the decision to the next owner.

My 2, Willie X

 

[Dick C]

The bottom is off....just took a little more effort!



I enjoyed the article that Roughbarked provided and if I thought that the weight could be saved I would have purchased the material and proceeded to remove the corrosion. In this case, the corrosion was so bad I figured that I had nothing to lose by putting it in vinegar for some hours with a baking soda bath to follow. So here are photos of the weight showing that the corrosion ate into the lead. Notice in the bottom photo the weight is not round so one wonders how this was cast in the first place. Note that this weight would have been cast sometime between the mid to late 1930s and the mid to late 1940s. What an education this message board provides!

Many thanks to those that contributed.

 

[shutterbug]

Lead expands as it cools, and it doesn't look like enough room was left at the top for that. So the lead was forced to expand outward, putting a lot of pressure on the shell. I've never encountered a wooden shell like that. Pretty cool find.

 

[roughbarked]

It is easy enough to melt lead and make a new one. The hard part is to make a mould that will fill the bill.

 

[Uhralt]

I would be tempted to protect the existing lead with some plastic foil and re-use it. Did you try if it will fit into the wood shell once you closed the gap?

Uhralt

 

[Willie X]

If it came out, it should go back in. If not, a little rasp work should do it. About 3 well placed dabs of E-6000 craft adhesive will keep it together for at least several more generations and it won't be to hard to remove if need be. Willie X

 

[Dick C]

I have the shell pulled together with elastics at the moment and I have not attempted to put it back in yet.

My concern is whether I have stopped further corrosion or or other methods are needed along with a protective coating are needed.

 

[roughbarked]

You'll likely have to seal the lead from exposure to the atmosphere.

 

[Willie X]

I have used oil, grease and linseed oil on lead. In your case I think the linseed oil would be best. It's a drying oil. You can thin it a bit with turpentine and it will dry in a week or two. One good dripping coat and wipe off any excess after about 30 minutes. Grease would be good too, a thin even coat rubbed on and wrapped in plastic, etc. Grease will also dry but it may take 50 years. Willie