Cylinders

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: