Just an update!
My first bottle of Canada Balsam no longer pours, but is still usable by geting a piece on the end of a glass rod, or similar, and letting it contact melt off onto the warm glass.
This time I have done an older lens - the Ross Actinic doublet - the Ordinary Angle version. This is one of the attempts in the battle for the "RR" design!
About half the balsam layer was discolored yellow. It took the usual 7 days of Xylol soaking. Once again, the balsam had left a Chalk looking deposit over the whole of the concave surface. Again this was removable quite easily with water based solvents.
This was very different type of lens mounting. The photo shows the cell with half the blacking enamel in place. The cemented lens is much smaller than the mounted lens - which is part covered with black paint or shows its mat rear surface.
This is good in respect of escaping the trouble with fiddling with the brass but means that fixing the cleaning lens in the balsam hardening process is more tricky. It also means that a total balsam failure would mean the demise of the lens as it would fall off.
I have just painted one side of the lens to show the GG surface of the fixed lens. The other side is fully polished. I suppose this use of "oversized" lenses is the price you have to pay for standardisation of mounts/barrels. This is the 4x5" size.
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