Dissolving the hardened grease in the 58mm Biotar and Industar 26
A frozen lens helical can be disassembled to remove hardened grease, but getting the threads lined up for reassembly can be a nightmare. This seems to be common with aluminum alloy lenses made during the 1950s and 1960s.
Some of you may have tried lighter fluid which works great until it evaporates. Heat guns also free the helical, but only while the grease is warm.
Two years ago, I experimented with Liquid Wrench on a frozen Carl Zeiss Jena Biotar. The lens remained usable for over a year but I didn’t use the lens on a weekly basis. I recently reapplied the Liquid Wrench and it works great. Note: use in a well ventilated area, preferably outdoors.
Press lightly on the nozzle to release a very small amount of penetrating oil on to the threads inside the Biotar, then turn the focusing ring back and forth throughout its entire range.
Use a cotton tipped applicator to pick up excess fluid and dry with compressed air.
With the Industar 26, apply a light stream of Liquid Wrench along the areas marked with red arrows. Turn the helical and work the penetrating oil into the helical grease. Use a rag to clean up the excess.
Make sure all the solvent has evaporated before using it on your digital camera.