Some months ago I was asked to chemically black some bolts I made for a V twin BSA. From passed experience personally and as a defence contractor, neither chemical or oil blackening lasts very well. So I spoke to one of my plating subcontractors and he said they now did zinc plating with a black passivation. So I had the bolts finished in this. It looked ok.
I tried some gun black on a freshly blasted stainless part and it had no effect at all...So a chemical/process for the specific job will be required I imagine...Ian
And that matches what I have found on my early projects..
Quite a few nuts and bolts on these early bikes where painted....I have not studied it in detail but think that bolts and nuts which are not likely to be used in normal service are painted, like these headlamp bracket bolts/nuts, certain mudguard bolts etc.
And those who are more likely to be used, like the detachable rearmudguard, frontmudguard stand, the steering clamp bolts etc. where cadmium plated.
It's quite funny that this is being discussed I'm in the progress of putting my front light brackets on now, I know some are more rivet counters then others and dont want to spoil a good post with a diffrant slant.
My Grandad was a dispatch rider in the BEF ,Africa and Dday onwards, when I turned up on my m20 years ago before he passed, he pointed out that the 1st thing that a Donr did was go to the stores and get a pot of paint and paint the shiny bits especial bolts ,nuts and even the levers etc. He said some guys painted the engines also but if a inspection was going to happen you would have to scrape the paint off , nuts and bolts and other bits didn't matter. Having items painted in Africa was a must as something could catch the sun and be seen from miles away , you also had a standing order not to go to fast as it stirred up dust.
So essentially home front yes you could keep factor standard , everything else then think and use common sense .
At the end of the war my grandad got shot a total of 7 times and his ukulele got some extra holes in it along with his bikes and him .
Hi Michiel
your knowledge on early bikes is always great & welcome
I have looked again at the parts lists I have here - 1940 models - Blue cover
15-8994/6 - top bolt - short x 1
15-8993/6 - top bolt - long x 1
15-8994/6 - bottom bolt - short x 2
EA80/6 - Nut - 5/16" cycle x 4
/6 on the book lists finish as Rustproof black
Then on my Provisional Parts list - WD motorcycles
WM20 - 14,000 to WM20 18,000
Contract C5610
15-8994/11 - short bolt - x 4 - same bolt used in all - 15-8993 is deleted !
EA80/11 nut - 5/16" cycle x 4
/11 finish has now changed to Khaki green ( No 3 Gas Proof)
This information is found in the "Sundries" section of both list and supplement list
Another parts list I use is the following as it has illustrations which is unusual for wartime lists - at least in my experience
Lamp brackets, securing bolts and nuts are now located in the Fork section
15-8994 x 3 - no finish indicated
15-8992 x 1 - no finish stated - bolt re-introduced
EA80 x 4 - no finish stated -
For Info
Lamp bracket bolt (19/32"-5/16 cycle 26tpi)
Lamp bracket bolt (21/32"-5/16 cycle 26tpi)