how to clean a silver cob

Can anyone shed some light on how to clean a silver cob? I have what I think is a 1/2 but still cannot tell because it needs a good cleaning but I have no idea how to do it without damage. I tried washing soda and a electro plate. Any help would be appreciated.

Sometimes you are better off not cleaning it at all.

First weight it with a gram scale so as to determine what
actual "mass" may be left.

Depending on where the coin was found, {near iron, under water, etc...}
has a determining factor on what may actually be left of it.

Post some photos.  There are more than a few of us
with some experience, who will be glad to
advise you - PRACTICALLY - about what you may need to do.

[Definitely worth the 2.9 meg download]

Can anyone shed some light on how to clean a silver cob? I have what I think is a 1/2 but still cannot tell because it needs a good cleaning but I have no idea how to do it without damage. I tried washing soda and a electro plate. Any help would be appreciated.

This may be a little technical unless you are a chemist or engineer - excellent resource though....
http://nautarch.tamu.edu/crl/conservationmanual/File13.htm

Maybe this simplified version....
http://www.mycoincollecting.com/col...ng/cleaning-coins-electrolysis.html

This is certainly a definitive resource on marine conservation, available for no charge in PDF format. Definitely worth the 2.9 meg download....
http://nautarch.tamu.edu/crl/conservationmanual/

Stan