Calculating the "Potential SG" of Potatos

I'd like to add Potatos to my Ingrediants list as an adjunct to try an old style american recepie.

How do I work out the Potential SG? I'm guessing it involves a kg of solids in a litre of water or something

I think most people boil the potatoes before they add them to the mash. I would say shred then boil the potatoes until they are soft (20 min should do for shreded), and take a gravity reading to see what their potential would be. I read about this in a Papazian book, I think it was "The Complete Joy of Homebrewing". But I would have to check to verify. I don't remember him putting a potential to it.

I would be interested to see what you came up with on the potential gravity and how many pounds you used.

Cheers
Preston