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Oxidation On Lead


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#1 icd leadlight

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Posted 05 July 2007 - 03:49 AM

I have a problem with oxidation on lead came. I have installed a new window in my bathroom and I am getting a lot of white spots (lead oxide ?) on on the lead on the inside of the panels only. I used patina on the lead.
I presume that this oxidation is due to condensation and reaction of the lead with water, but stained glass has been installed and open to the elements for hundreds of years. I don't think that this is due to poor quality lead. Is there a problem with lead came in moist environments? How can I remove it and prevent it coming back? Help.

#2 Boris_USA

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Posted 05 July 2007 - 07:10 PM

QUOTE(icd leadlight @ Jul 5 2007, 03:49 AM) View Post
I have a problem with oxidation on lead came. I have installed a new window in my bathroom and I am getting a lot of white spots (lead oxide ?) on on the lead on the inside of the panels only. I used patina on the lead.
I presume that this oxidation is due to condensation and reaction of the lead with water, but stained glass has been installed and open to the elements for hundreds of years. I don't think that this is due to poor quality lead. Is there a problem with lead came in moist environments? How can I remove it and prevent it coming back? Help.


A bathroom is a high moisture content area. You may be able to slow oxidation down, or stop it for perioids, but lead will oxidize. Yes, lead has always been exposed to elements in windows for hundreds of years, and in those hundreds of years, it has always oxidized also. The oxidation actually forms a protective coating for lead. In your case, I would try plain clear paste wax, which you can easily redo when the need arises. Sealing with lacquers or hard sealing products would still be temporary, and a lot harder to redo, if needed, if oxidation started again under the coating. Wax may be an old solution, but still the best one I have seen so far.

#3 icd leadlight

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Posted 08 July 2007 - 09:16 PM

Thanks Boris. You are right; I think waxing the lead is the answer.
I have done a bit of research since I posted the message. You may be interested. I assumed that the oxidation process involved the formation of lead oxide (PbO) and this provided the protective layer. However, its not that simple. Lead forms a series of oxides,. The principal ones are PbO, a yellow oxide called litharge, and PbO2, a reddish-brown substance called lead dioxide, Orange-yellow Pb2O3, while red Pb3O4, red lead or minium. In addition to these, there is Pb2O, lead suboxide, a black, amorphous substance
Basic lead carbonate, 2PbCO3•Pb(OH)2, when pure, is a brilliant white substance that makes an excellent paint pigment, called white lead.
(ref: http://www.du.edu/~j.../lead.htm#Chem)
: Perhaps lead's best known property is its resistance to corrosion in various aggressive environments Lead's ability to give good service in such situations often gives the erroneous impression that lead is a passive metal. Lead is, in fact, a very reactive metal and it is this reactivity which enables it to be used in corrosive environments. In air, for example, a close fitting and adherent film of lead carbonate is formed by rapid reaction first between metallic lead and oxygen to form lead oxide followed by a second reaction between the lead oxide film and carbon dioxide, which is always present in air, to form a protective film of lead carbonate. Further contact with the metallic lead underneath is then prevented and corrosion ceases.
Lead patina is actually a layer of highly insoluble lead salts, including lead carbonate, which gradually form on the lead surface to eventually give the familiar grey lead appearance.
During the initial stages of the oxidation process, lead can display various colours including blue, bronze and green. It is probable that such films are extremely thin and in fact have no intrinsic colour but appear coloured due to an interference effect Similar interference colours may be observed when oil is present on a wet road. Lead is most likely to appear coloured when placed indoors or in protected locations.
When lead comes into contact with moisture, rainwater, condensation etc, at early stage, ie my bathroom, discoloration, spotting and white powdery deposits (usually basic lead carbonate) can form and may ‘run-off’. The degree to which all these occur is governed by the environmental conditions, but with longer term weathering, the lead will take on its’ familiar appearance.
Investigations have shown that the patina formation follows the route: lead, lead oxide, basic lead carbonate, normal lead sulphite, and normal lead sulphate. The ‘run-off’ stage occurs when non-adherent basic lead carbonate is formed, usually through contact with moisture. Each of the stages in patina formation is adherent, highly insoluble lead salts and in practice, as these salts develop with weathering, they stifle the basic lead carbonate release. The final patina is made up of approximately 30% normal lead sulphite, 60% normal lead sulphate and 10% normal lead carbonate. However, this can vary dependant upon location, time and airborne impurities.
(Ref: http://www.smashingw...com/faqs.htm#7)
I believe, what I have experience is an accelerated rate of oxidation, as this is a new window. The ‘scale’ needs to be cleaned off ASAP and a wax coat applied. I have some ‘Alna’ Teak wax that I think will do the trick.
Another point, Although lead is very stable in sulphuric and hydrochloric acid, it is particularly susceptible to organic acids, such as acetic acid, humic acid, and tannic acid. Lead, therefore, should not be stored in oak cabinets or drawers. If so, even small concentrations of vapours of these acids can initiate corrosion, which progresses rapidly. To be safe, lead should by stored in sealed containers or polyethylene bags.



#4 Dennis Brady

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Posted 08 July 2007 - 11:40 PM

QUOTE(icd leadlight @ Jul 5 2007, 04:49 AM) View Post
I have a problem with oxidation on lead came. I have installed a new window in my bathroom and I am getting a lot of white spots (lead oxide ?) on on the lead on the inside of the panels only. I used patina on the lead.
I presume that this oxidation is due to condensation and reaction of the lead with water, but stained glass has been installed and open to the elements for hundreds of years. I don't think that this is due to poor quality lead. Is there a problem with lead came in moist environments? How can I remove it and prevent it coming back? Help.


You can't totally prevent it, but you can minimize it. Next time don't use patina. Instead, buff the lead with a natural bristle shoe brush. If you use a linseed oil based putty, the brush will pick up enough oil. If not, apply some linseed oil with a cloth and then brush it vigorously into the lead. The buffed on oil will turn the lead a dark pewter colour and provide a protective coating.

#5 Boris_USA

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Posted 10 July 2007 - 08:55 PM

QUOTE(Dennis Brady @ Jul 8 2007, 11:40 PM) View Post
You can't totally prevent it, but you can minimize it. Next time don't use patina. Instead, buff the lead with a natural bristle shoe brush. If you use a linseed oil based putty, the brush will pick up enough oil. If not, apply some linseed oil with a cloth and then brush it vigorously into the lead. The buffed on oil will turn the lead a dark pewter colour and provide a protective coating.

Never thought about linseed oil, but since it does not dry easy, if at all, it would be worth trying. I use an electric old shoe shine brush with rotary brushes, and it works great for all stages of cleaning excess putty to polishing the glass and came. For the final coat, I use butchers block paste wax, put on with a short bristle cut off paint brush. Works great for me. Will try Linseed oil on next project.

#6 Boris_USA

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Posted 10 July 2007 - 08:57 PM

QUOTE(icd leadlight @ Jul 8 2007, 09:16 PM) View Post
Thanks Boris. You are right; I think waxing the lead is the answer.
I have done a bit of research since I posted the message. You may be interested.


Thanks, always interested in information.

#7 e hilton

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Posted 16 July 2007 - 04:08 PM

Could you use boiled linseed oil, like what woodworkers use?

#8 Boris_USA

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Posted 16 July 2007 - 08:46 PM

QUOTE(e hilton @ Jul 16 2007, 04:08 PM) View Post
Could you use boiled linseed oil, like what woodworkers use?

I dont see why not, its what I use. A lot of woodworkers are leaving "Linseed Oil" in favor of wax. Antique restorers hav just about stopped using it. It is included in all the recipes I have seen for making putty, for glass/lead sealing. Its also the thinning agent for a lot of commercial putty. I intend on giving it a try, although enough of it should be on the lead already, after its puttied. We will pay attention next project.




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