I think it would help to know if you mean to remove dirt from a metal surface or metal corrosion because "cleaning" is not always referring to "removing strange material from a surface".

Dear Teresa

You asked about the methods of cleaning and protection of historical lead. there are different techniques to clean lead some by using acid by little concentration and anther technique by removing the corrosion by some delicate tools also by some Professional archeologist experts .I did that many times in some doors and windows in historical Masques and houses in Egypt., send to me what the methodology of your research if I can help for that.

Best regards

Hossam

You need to talk to specialised metals conservators and ask for their help, not archaeologists. Try CoOL (Conservation onLine) and search in their directory for metal conservators.

A conservator can assess the condition of the object, identify the reasons that brought it to its current preservation state, and perform conservation treatment without harming the object.

The questionnaire attached could be improved a lot, as you mention few methods, yet, the treatment depends on the condition of the object, and not all conditions are the same. In addition, I would like to notice that conservators do not perform electrolysis anymore. Our goal is usually to maintain what is left with minimum intervention.

Here are some  links to give you some idea about lead conservation, but be careful . I would not reccommend any conservation work (or cleaning) to be performed by a non specialised metal conservator, because any damage done by inexperienced people o metals is most times irreversible.

http://nautarch.tamu.edu/CRL/conservationmanual/File14.htm

http://cool.conservation-us.org/byform/mailing-lists/cdl/2000/1454.html

http://www.nma.gov.au/__data/assets/pdf_file/0008/346067/NMA_metals_s3_p05_organ_pipes.pdf

https://www.iiconservation.org/node/1145

Feel free to contact me if you have anymore questions