I've got Hasag 351 L yesterday (with black plastic wheel, not cardboard "supersaver" version). The tank was covered by previous owner with "secret antirust mixture". I suspect it is (after closer look) -- a manure mixed with tar, or pig fat mixed with soot... Alas, some rust bites the metal, but not dramatically. Rotary wire brush will do, maybe some chemistry too... Would you tell me please, should the tank be black, or dark green (RLM-70 Schwarzgrün)? The cage is black, part between bottom plate and the fount -- zinc plated, the vent around iner hood -- enamelled with very dark grey (looking like a gunmetal a bit), the top hat is missing. I'll send the pics soon.
So, there's the beast. Decal -- destroyed by the handle. It will be totally removed while brushing the rust, alas... After first encountrer with rotary brush (nylon strings filled with abrasive). The dirty beast...
More surprises. Someone apparently tried to plant potatos in the lamp... Secret of the gardener unveiled... Is something alive there? Lonely island... After brushing with rotary brush and priming with Brunox anti-rust agent. The bicycle hub with M10x1 thread appears to match the thread of the tank and serves as handle...
