The rotodip was a process used by BMC to coat both
vehicle bodies and other metal items not welded to body with a special
rust proofing agent.
All Mini, 1100 & 1800 bodies were rotated through the rotodip during
the painting process. Allowing primer to take to normally inaccessible
areas. The bodies complete with doors, bonnets and bootlids were fully
immersed and were rotated a six - stage phosphating machine.
The bodies had a large rod inserted through the grille cutting, and
through the remove able panel in the bulkhead, before the rod came out
through the boot opening. The body was clamped to the rod so that there
was no movement while the process was being carried out.
In the first stage the bodies were dipped in a tank which had a heated
alkali solution to remove any oil and other contaminants picked up during
the building process. The second tank was filled with cold water to rinse
off the alkali solution. The third tank contained hot water, which ensured
that the body was perfectly clean before it entered the phosphating tanks.
If there was any contamination left on the bodies then the rust inhibiting
solution wouldn't be as effective.
After the initial stages the bodies would then be run through the
phosphate solution. High pressure jets sprayed the solution into every
inaccessible area of the body. The phosphate solution acted as an anti
rust agent, so that if the body was accidentally damaged it would stop
rust coming through, and it also acted as a bond so that the paint would
take to the steel. After this processing the bodies were once again washed
off in a tank of warm water to clean off any excess. After the wash the
body was placed in an oven to dry the solution before being coated in
The painted bodies were then moved to a oven, where they would baked
for 30 minutes at 171 degrees Celsius.