brackets and bolts finishing

[ditomagico]

Hi All

Restoring a couple of 1984 RZ500..

Need some help with the Yamaha brackets and bolts finishing (i.e. Master cylinder oil pipe bolt or the bracket on top of the radiator and coolant caps) . I'm not sure if the dark grey is painting or plating?

thanks in advance for your help.

Ditomagico

[rd84]

They are very dark olive zinc plated on my bike (the appearance is almost black) - there are variations on this throughout the bikes production though so don’t let anyone tell you that there is just one finish on the plated parts.

Cheers
Paul

[ditomagico]

Hi Paul

thanks for the reply . I noticed that the allen key bolts are black .. so I think is a black zinc plating. Some bolt and nuts instead are is yellow zinc. then some other bolt and the majority of the brackets are that olive color .. maybe black nickel plating?

[Almac]

The colour is obtained from the passivates not the zinc process.

When the part is zinc plated the zinc Layer is soft and has a dull grey finish. Chemicals in the solution help to brighten the plating and you can also dip the zinc’d part in nitric acid to brighten it further.

To give the part its colour and to harden the surface the part is then dipped in a passivate solution. The passivates come in clear/blue, yellow (gold), olive drab and black.

The final colour can substantially change depending on how long the part is left in the passivate, passivate temperature, passivate chemical makeup and the initial finish/colour of the zinc plated part.

Basically, whether you plate yourself or get a professional company the colour may not match the original part, the original parts may not be identical bike to bike from factory and over time the passivated parts do change colour.

[ditomagico]

I wasn't sure if the black bolts are back nickel or black zinc plated .

I did an test with the chloridic acid and I can confirm that the bolts are black zincked from factory. The original passivation process must have been very quick as the bolts are not fully black but keep a chromatic effect.

[rd84]

That's a good piece of research

Cheers
Paul

[ditomagico]

Thanks Paul!