RobTV175 wrote:Well, I’ve scrubbed and scrubbed including what is the nearest thing I can find to gunk here in italy “industrial garage degreaser” and while it is significantly cleaner, it is still badly pock marked for about half the area of the chaincase with ugly dark patches. Are there any other tricks that I can try? Dean at Rimini can’t offer the acid dipping service at the moment as he is between providers.
John Haigh preferred sulphuric acid for his dipping service.
Seriously though, I use DEB Janitol Altrans:
https://www.debgroup.com/uk/products/janitol-altransBiodegradable, acidic metal cleaner specifically formulated to remove rust, oxidation and corrosion from most metals. Usual precautions advised.
Works well for me on engine casings, carbs etc but they must be free from oil/crud. No need to immerse the casing and I have obtained best results if applied and agitated vigorously with an old paint brush when it will foam. Several applications may be required and rise off with water. Said to be to be biodegradable and can be flushed down foul drains. Leaves a matt finish very much like the original, not shiny like in the Rimini pics. Expensive now but 5l lasts me ages.
Careful though, it can degrade or remove plating on gear swivel, brake arm etc, leaves steel dark grey and will make your concrete fizz if you spill it.