Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: Murf on January 13, 2026, 10:26:08 AM
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I need to get the bolts and nuts for my 550 resto zinc plated, I have read through past posts on the site about this and have decided that I am not going to do it myself.
Can anyone recommend a good platers that will do the whole process ie. cleaning, preparation and plating.
I would do basic cleaning, rust removal and degreasing of the parts before hand of course .
I am in the East Midlands but will send or take the parts to anywhere that is a well recommended company.
Thanks
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My local plater switched to anodising years ago and I haven't found any where that will do non commercial stuff or vehicle restoration bits. I'm just in the process of pulling a set of carbs apart, all needing yellow zinc. Last summer I had 4 tacho/Speedo bases to do and the 3 quotes I got back from commercial platers ranged from 50 to 100 quid plus vat and postage both ways. I did them myself in the end but without proprietary brighteners in the bath the finish isn't mirror like but this didn't matter since they were covered over with black epoxy. The above platers were the ones that come out top on the search engines.
I searched around to see what I could find this time around, looking on car restorers forums and come up with DDG plating in Nottingham and they seemed like a candidate to try this time around. Still a 3 hour round trip for me though , twice.
I'm also looking to alter my bath chemistry to improve things and try to source some proprietary brighteners in small enough quantities to make it viable.
There a lots of videos on u tube of people shining up dull plating with a wire brush and things do look shiny but without passivation the coating will degrade quite quickly, that's if they haven't brushed most of the coating away already.
Be careful with any high tensile bolts or springs as they will need oven baking soon after plating to expell hydrogen to avoid embrittlement. Some platers can do this.
Regards
Dave
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I think my mate Graham Curtis uses Derby Platers for zinc. Minimum order there though I think.
http://www.derbyplating.co.uk/services/
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I've used this firm on Abbey Street a few times over the latest 10 years for Chrome Plating, excellent job, turn
round time was long as they seem too always have a lot of work in hand.
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I did most of the plated parts on my cb550, takes ages and a fair amount of room to do with some mixed results early on but soon got the hang of it. Would I do it again? Maybe but only because I have the kit now, definitely don't rule out going diy
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Thanks for the replies,
I believe Derby plating has ceased trading, they are just open to finish off orders they have but not taking any new work on. Yet another one los.
DDG plating are only about 5 miles from me and they do hexavalent zinc plating which is supposed to be more corrosive resistant and less toxic and polluting than trivalent plating. I have phoned them and they will do small batches for restoring work. However they will not clean the parts, you have to clean them yourself. They told me that the parts go in the plating tank exactly as you bring them in, if they have rust or grease on them then they won’t come out very well.
I have had a go at cleaning and degreasing some of the bolts I have and have given them a session in my ultrasonic cleaner, they have come out very clean but have a sort of brown rainbow colour to them. I suspect this is a reaction between the cleaning fluid and the remaining zinc plating.
I have no idea if they are ok or not to be replayed so plan to take some to DDG and see if I can get to ask someone there. I am also worried about flash rusting on any parts I do clean before they get replated.
I will keep you informed.
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A soak in white spirit to shift most of the grease then oven Pride is your friend if there is stubborn grease. Warm it up to speed things up. If there is any deep pitting with rust in them they won't plate and you'll be left with black spots in the finish. Either electrolytic clean or a long soak in warm citric acid solution so that the pits are showing metal.
Once past this stage they need to be kept dry to prevent further rusting because any residual plate will be gone.
The platers will degrease and pickle as part of the process but mostly to clean off polishing compounds and cutting fluids from manufacturer of new components. Any black gunge might not be removed, also they don't want their baths crapping up.
I doubt they are still using hexavalent chrome as that has been banned through some end of life vehicle directive. They will probably be using a trivalent yellow passivate that gives a similar appearance to the old hexavalent finish. If you need a clear passivate on some stuff best to bag them separately to those needing yellow.
Regards
Dave
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Wasn’t hexavalent chrome the stuff in the Erin Brockovich film?
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I started re-plating parts a few years ago when the local plater ceased trading. A bit of a learning curve and research but now I get good results. Although most parts I'm re-plating are unseen.
The procedure place the parts in vinegar if rusty, that dissolves the rust and will also remove zinc plating. That can take a few days, then into brick acid and rinse. Dry off with heat gun. Some flash rust can appear.
Now ready to plate after a dip in caustic soda, a rinse and a dip in brick cleaner followed by a rinse. Now in the plating tank, It takes a bit of trial and error to set the amps correctly. Probably takes about half an hour on the larger bases and a bit less on smaller ones. Out of the tank, a rinse, into the passivate followed by a rinse. A drying cabinet would be ideal as despite a final rinse the passivate does sometimes leave slight stains.
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Those Speedo bases look shiny enough for me.
What bath chemistry and brighteners are you using? Alkaline zincate or acid chloride?
Not sure about using vinegar though, makes me cough and gag if I spend too long sniffing that. One reason I started using citric acid for stripping. Works quickly enough if you warm it up to 'cup of tea' temperature. Also citrate will chelate iron so more efficient than acetate for getting residual rust out of any pitting.(Same mode of action as evapourust)
I'm currently using boric acid to contro/bufferl the ph around the cathode, again less smelly than vinegar.
I'm just setting up to do all the metalwork on a set of carbs.
Getting hold of chemicals needed for making your own brighteners is impossible in the nanny state that we live in.
Regards
Dave
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I just use the zinc plating chemicals from Gateros. The brighteners they use are spot on. I know they sell the top-up 'maintenance' brighteners separately but not so sure about the brightener they use on initial mixing of the zinc electrolyte. I did once try YouPlate zinc plating chemicals but big mistake as the brighteners they use gave me crap results. I discussed this with them but in the end I just bolted with my feet at went back to Gateros. I have seen saccharine suggested as a brighter but never tried it.
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Thank Ash,
That's where I have been looking, there's the leveller make up and brightener available.
Other brighteners could be aliphatic polyamines, furfural,thiourea, vanilla extract and derivatives.
Regards
Dave
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I too use Gateros and just add a few drops of their maintenance chemical if the the plating gets dull. Getting the amps right and the temperature at 25c. Bags on the anodes helps to keep the electrolyte clean and filter it after each use.
Fair to say the vinegar does stink a bit so I just keep it out of the way and it does take a couple of days to dissolve the rust. Some parts might take longer especially something like that shown in the image that's in it now. The river it was found in has not been disclosed!
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That's looking a bit of a mess. Though the plate inside looks like it's still there.
The worse bits I have seen on them is the outside at the bottom where they sit in water in the bowls and the pitting can be quite deep.
Regards
Dave
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[quote The river it was found in has not been disclosed!
[/quote]
Been magnet fishing?
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I have had a lot of success with Gateros chemicals. However, they used to sell zinc passivate chemicals that were hexavalent. However, they only sell less toxic trivalent passivate chemicals now and at the end of last year, I wasn't getting decent results with trivalent yellow passivate on some 400F carb bits so I contacted them via email. Here is the correspondence :-
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QUESTION from me to Gateros :
Hello,
I recently refreshed my zinc plating chemicals and, as always, got excellent results.
However, my experiences with the yellow chromate passivate both original formula and the new 2-part type are mixed. I did get some reasonable results but in particular with springs, I get instant smutting after the pre-dip in 5% HCl. I am thinking of trying a 1->3% dip in nitric acid instead. I have also read on the .net that if you blue passivate first and then yellow passivate you get better adhesion results. Another suggestion is that the brighteners in the zinc electrolyte affect the performance of the passivation ... but not sure how true that is.
I do have a small amount of the original, more toxic yellow passivate and also the new, 2-part yellow passivate. Given that I have both, then which do you recommend, is it best to use performance wise please? Obviously, the health and safety aspects need consideration.
I bought some olive drab passivate from you last year, as I have a registered business and results with that were superb.
Attached is a box of small parts I did with the new zinc solution / 2-part yellow chromate pass. Not too bad but the large spring took about 5 attempts (i.e. stripping completely then replating). I stretched the spring out on a former jig I made.
Best wishes. .... Ashley
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REPLY from Gateros:
Hi Ashley,
So in theory spring steel, once plated with a thick enough layer of zinc should passivate exactly the same as any other steel item.
In practice it is not quite that simple as springs are tricky to plate because as you have found you often have to use a jig to stretch them out and may also have to de-embrittle them after plating and before passivation.
I would also drop the percentage of the HCL you are using for activation and if you are using nitric then drop it to 0.5 to 1% maximum.
I have pasted a bit below on the yellow passivate.
The key with the yellow trivalent passivates is to remove as much of the brightener film from the surface of the plating before you passivate. The brightener film is on the surface of the plating and trapped in the tiny pores of the plating itself. This caused problems with both adhesion and can also lead to high iridescence in the passivat and staining.
Good rinsing is key for a start so 3 minutes under running tap water.
Then we activate in a dilute solution of HCL from 2 to 5% ( acid brick cleaner would need to be diluted ) then rinse again. You can also use the dry acid salt solution for this but HCL works faster and seems to work better. You can also use a dilute nitric acid solution so from 0.5 to 1%. If you use HCL or the dry acid salts you may see a little gassing on the part
After this activation dip and rinse it is then into the passivate. Always make sure that your passivate temp is about 25°C. Watch the time in the passivate and rinse well after passivation in clean rinse water every time.
I use a hairdryer on cool to dry the parts, you don't want it on hot.
We also run the zylite maintenance brightener level not too high, we aim for a bright finish but not like chrome, too much brightener causes problems with adhesion and gives high iridescence.
This should help you get a good yellow iridescent finish that looks good and sticks well.
No problem, I personally would use the hexavalent yellow but as a private individual you should probably use the new trivalent yellow
Kind regards
Dan
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I read somewhere that a hot water rinse helps remove brighteners from the surface that might otherwise cause poor adhesion of the passivate.
I have read so much recently can't remember where though.
Also from my previous life working in chemistry labs, nitric acid will eat organic matter, so might help disperse any residual brighteners. Certainly would dissolve fish livers and shrimp at the right strength. It's a strong oxidiser as well as an acid.
Regards
Dave
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I found that you can buy nitric acid online from APC-Pure but only in low concentrations but that's fine for what I was using it for. Think it was 2% ... any stronger they won't sell to Joe public...even the 2% had to be diluted to around 0.5-1%
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Yes it's a precursor for making stuff that goes bang!.