To attack some of the rust, I have made a solution of Toulene, Methylated Spirits, Soda Bicarbonate, and some washing up liquid.
To make a good degreaser you need:
Something to thin the hydrocarbons (grease, oil, grime, etc), I used Methylated Spirit and Toluene solution (1:1),
Something to raise the Alkaline level, I used Soda Bicarbonate
A Surfactant, to treat the surface of material, I found washing up liquid did this the best.
Finally, I added a bit of water to bulk the solution.
Thinners 45%
Water 45%
Soda Bicarb 5%
Washing Up Liquid 5%
Sat the cylinders in a bath of this overnight.
Before:
After:
May not look like much but they are now very dry and ready for de-rusting.
Soda Crystals (1 Tablespoon per Gallon of water)
An anode of sacrificial iron bar (re bar)
with the unit as a cathode
Battery charger (5 amp / 24 volt)
Run a current across the units in the solution and the rust comes away:
Wash them off and light brushing
Before and after: