Nut and bolt plating

Norton was a bit different from most and used a satin (dull) chrome on nuts bolts and washers. Some items were polished ,fork top nuts,seal holders ,shocker inner covers wheel nuts etc. Washers and nuts were mostly bevelled on the top faces.

Richard

If you enter 'dull chrome' in 'search site' you will find lots of info and discussion regarding the dull chrome finish Norton used up until the '50's, and maybe into the sixties as well. Look on the 'Pre- war ES2 restoration' in the 'dull chrome' heading and there is mention of Will Horgan, who makes a good range of stainless parts. If you bead-blast stainless it comes up with a finish not far from dull chrome.

There are chrome finishers that still do dull chrome, but my experience is that it is not advisable on fine threads, they tend to get choked up with the plating. The original Norton plating was superb, easy threads, good corrosion resistance, and it seemed to be soft enough not to crack off under a spanner.

Incidentally, I recently acquired a sixties P11A Norton, with most of the original fasteners done in cadmium. Not generally available anymore as it is toxic. I do know of a company that will plate motorcycle fasteners in cadmium, obviously be aware of the dangers, and be prepared for eye watering prices!

Roger.

As Roger says, 'Dull Chrome' is something special. Don't be fobbed off with 'satin chrome' which seems to just be a brushed finish over dull nickel.

No-one in the trade seems to be able to explain exactly how 'Dull Chroming' was carried out. I suspect that there is a good chance that it was a process involving hexavalent chrome (chromium VI) which is horribly poisonous and now banned throughout the European Union.

It was a supreme motorcycle finish. I have original areas on my 1939 16H and it is not deteriorating but later plating is...

Raleigh and Sturmey-Archer seem to have used it on bicycle parts until the mid 1960s but I can't think of any later examples. I'm not sure with Norton that it survived the move to Woolwich.

The best impersonator of dull chrome that I've found in the UK is Collins Chemical Blacking but even they are not 100% consistent. Some of the WD chaps in Holland have got a good source at the moment, although it is a little rough to the touch.

In my opinion, it's worth investigating the possibilities...these things make the difference if aiming for a true 'period' restoration.

Previously richard_payne wrote:

As Roger says, 'Dull Chrome' is something special. Don't be fobbed off with 'satin chrome' which seems to just be a brushed finish over dull nickel.

No-one in the trade seems to be able to explain exactly how 'Dull Chroming' was carried out. I suspect that there is a good chance that it was a process involving hexavalent chrome (chromium VI) which is horribly poisonous and now banned throughout the European Union.

It was a supreme motorcycle finish. I have original areas on my 1939 16H and it is not deteriorating but later plating is...

Raleigh and Sturmey-Archer seem to have used it on bicycle parts until the mid 1960s but I can't think of any later examples. I'm not sure with Norton that it survived the move to Woolwich.

The best impersonator of dull chrome that I've found in the UK is Collins Chemical Blacking but even they are not 100% consistent. Some of the WD chaps in Holland have got a good source at the moment, although it is a little rough to the touch.

In my opinion, it's worth investigating the possibilities...these things make the difference if aiming for a true 'period' restoration.

Richard, I have a 1937 International to racing specs as confirmed by the factory records. In the records as in my 1937 sales catalogue, the petrol and oil tanks are dull chrome plated. After finally getting the correct piecrust tank in the UK a couple of years ago, I have been trying to identify what dull chrome was for the last 18 months as it was not listed in my "Cannings Handbook of Electroplating". I have been in contact with all of the Norton experts in the UK and the plating chemical supply houses here in Australia. One of my ex employees supplies plating chemicals here in Australia and through the network of old plates found someone doing it here. After sending my tank to Sydney it was found that the plating tanks could not accomodate my petrol tank.

However the process is as follows (as there may be platers doing this process in the UK). The process is essentially dull nickel plating over plated with a flash of chromium. Another one of my plating text books advise that this process (and I quote) ..."when this deposit is overplated with decorative chromium it gives a pleasing dull chrome effect, similar the finish on micrometers and similar tools"

The zinc plating bath is called Watts nickel and consists of 240 g/L Nickel Sulphate, 45 g/L Nickel Chloride and 30g/L Boric Acid. Current density is from 10 - 40 amps per square foot. Aiming for about 25 - 35 microns of zinc.

Preparation is typically cleaning and pickling followed by alkaline (cyanide) copper for tanks to prevent acid being trapped in the seams.

regards, Ian

On your home kit did you after the plating fix the zinc by passivating, this can add a blue or gold tint but slows down the blooming you get as the zinc reacts to moisture. Its just a solution you dip the plated parts into for a few seconds and then let air dry.

I have a 1939 ES2 and I used stainless nuts and bolts with reduced heads throughout. Mainly because I could re-shape the heads on the lathe to a dome pattern as original spec. I then polished them for some fittings ie- handlebar clamps but bead blasted the others. they look as good as new even after six years.

As for the tank, I have the three and a half gallon "Inter type" which should be dull chrome plated, as it was more like a collender, I painted it instead, after a patch job. However I would like to respray it with chrome paint. Has anyone any experience of this product?

BSA WD B40s had dull chrome plating - don't want a gleaming shine when hiding from people who aren't keen on enhancing your well-being. So many have been stripped to make pre '65 trials machines (although they are not in fact pre '65, but that's another story). There must be piles of discarded dull chrome fasteners lying around somewhere.

You only need to keep the part in the passivate solution for 20 to 40 secs.

On the galling yes Stainless does gall easily so you need to use copperslip on all threads and I do it regardless of the grade. Galling happens on a molecular level where 2 parts of the same alloy bond at the joint, I have had bolts shear when undoing the joint was so strong. Not tried it but using a different grade stainless on the nut from the bolt should reduce the risk as then the 2 alloys are not exactly the same but much better for them to not touch which is where the copperslip come in.

I bought a large mixed bag of various BSCY nuts and bolts from Nooky's Nuts. The very bright zinc plating looks very much like chrome and saves a fortune. Many have half height heads and all heads are smooth without numbers or letters embossed. Will use these for all my restorations...much stronger than SS too and no worry of them "welding" up.....Les