Chrome plating - progress and advice on next ateps

[David9694]

The photos are of an old Raleigh Gran Sport frame, and a pair of forks that came with a different frameset and which were a pretty sad pitted specimen. Some Gran Sports I see on-line (but not in the Raleigh catalogues) have chromed rear ends, so I thought I’d try for this. I collected them both from Dorsetware in Poole today, having dropped them off just before Christmas. They charged me £120. My next step is to paint the frame (I got the Caramel shade colour matched last year).

I’d be interested in polishing up the head-lugs - will they polish up sufficiently, do we think?
Any advice on primer for the plated but not polished areas?

Where the polishing ends

General view of the frame

Fork legs

shimano fork end

[thatsnotmyname]

I’d be interested in polishing up the head-lugs - will they polish up sufficiently, do we think?
Any advice on primer for the plated but not polished areas?

Depends what you mean by 'sufficiently'..? You could have got them chromed at the same time you got the ends done? Either way, you're unlikely to be able to match the finish of the chrome.

Not sure what you mean about priming a plated area. If you're going to paint over it, then I'd think about removing the plating first.

[al_yrpal]

Chrome is extremely hard, you cant really polish it You can only get it stripped polished and replated. That involves a copper flash, then nickel and finally chrome.

Al

[Mick F]

Wot he said. ^^^

You can't polish chrome.

[fastpedaller]

As above - it can't be polished. the 'polish' is done before the plating process. The parts required to be 'highest quality shine' are polished before the plating process - if you were to see the steel parts they would look 'as shiny as chrome' before any plating is done. Regarding the primer, IANAE (I am not an expert) but suspect an etching primer would be the first coat (especially where painting over chrome) followed by the 'usual process' of undercoat and topcoats that would be used (irrespective of if the frame has chrome), but someone with more knowledge will hopefully be able to give a definite answer.

[Brucey]

as per answers above, the usual route is

- polish the steel to a mirror finish
- copper plate
- nickel plate
- chrome plate.

The chrome layer is the thinnest of the three. Occasionally I have seen an extra-thick layer of copper used, so that imperfections can be polished out in the (thicker than normal) copper layer, instead of threatening the make the (pitted) steel too thin though being overpolished.

Any attempt to polish a rough-looking chromed surface will soon breach the plated layers and leave a mess.

It looks like they plated your entire frame, but only polished the parts you wanted to show. Painting over chrome is not foolproof; the roughness aids paint adhesion and further roughening with abrasives (or light grit blasting) can help the paint to stick. The other weapon at your disposal is the correct etch-primer; this can act as a good base for further paint.

cheers

[David9694]

as per answers above, the usual route is

- polish the steel to a mirror finish
- copper plate
- nickel plate
- chrome plate.

The chrome layer is the thinnest of the three. Occasionally I have seen an extra-thick layer of copper used, so that imperfections can be polished out in the (thicker than normal) copper layer, instead of threatening the make the (pitted) steel too thin though being overpolished.

Any attempt to polish a rough-looking chromed surface will soon breach the plated layers and leave a mess.

It looks like they plated your entire frame, but only polished the parts you wanted to show. Painting over chrome is not foolproof; the roughness aids paint adhesion and further roughening with abrasives (or light grit blasting) can help the paint to stick. The other weapon at your disposal is the correct etch-primer; this can act as a good base for further paint.

cheers

They have indeed put the entire frame through most of the process. Getting chroming done seems to be a bit of a dark art, so I though I’d try it out and post my results, lead times and costs ( they said the rear end polishing was £40 out of the total). I guess it would be the same again to have it professionally painted - but this will be aNother rattle-can effort of mine.

I get that I can’t now polish-up the unpolished areas (and for my next trick, I’m going to mix radial and cross-ply). However, if the unpolished area can’t show, then they’ve got to be painted. The lugs was just an afterthought. The unpolished plated areas, I.e. the main tubes, do need smoothing down.

If the chrome-plating process involves physically dipping the work piece in various tanks of chemicals, then it makes sense to me to treat the whole thing - there was a lot of sucking of teeth about the amount of masking that would have otherwise required - this would be more substantial than a rolled-up page from Cycling Weekly stuck down with tape.

Interestingly, they must have sealed-up the frame openings, and I noticed when I got it home that I’d left the adjusters in situ - one of them turns by hand!

So etch primer, followed by normal primer?

[thatsnotmyname]

So etch primer, followed by normal primer?

If you're using an etch primer, there's no need for another primer on top. In general though, it sounds like there's been a bit of mis-communication between you and the platers.

[David9694]

So etch primer, followed by normal primer?

If you're using an etch primer, there's no need for another primer on top. In general though, it sounds like there's been a bit of mis-communication between you and the platers.

I’m a contractor, so sometimes it’s wall-to -wall work, whereas this month, I’m on my backside*. In work mode, it’s difficult do deal with places out on industrial estates only open M-F (although some start at 7.30 am). I took it in on 23 December, being the only time there was someone there, and I had finished for Christmas. They rang me on a busy morning the first day back in January about the all over plating. My other problem is not knowing what for them is easy and routine and what is a pain in the bum for them and expensive for me - for example for local sprayers/ powder coaters, applying decals pre-lacquer or doing a contrast panel - The latter is tricky I know.

But I’m not unduly worried about the chrome because on a couple of refurbs I did last year I noticed shiny metal where original paint had chipped, where there was chrome plating further up.

* can’t say ar** on here, it seems; let’s try backside, see if likes that

[Brucey]

the main purpose of using coats of normal primer/undercoat over the etch primer is (of course) so that you have enough undercoat thickness to allow the paint to be wet flatted before the topcoats, without which the paint job will be utter rubbish. (*) It can also (if the undercoat is say zinc rich) provide additional corrosion protection.

FWIW some folk like the 'matt chrome' look. It is interesting and different, if it is not too lumpy. You could try masking off the head lugs and then just clear coating them when you clear-coat the rest of the frame.

(*) if you rub through the etch primer coat then it will have to be repaired. It turns out that some paints are incompatible with one another, but only when the layers are in the wrong order. So for example you may find that your undercoat works just fine over your etch primer, but causes horrible cracking when the layers are the other way round. This sort of thing can drive you berserk should you have to repair the etch primer coat because you rubbed through it. Ask me how I know this....

FWIW the traditional way of plating part of a bike frame is to have that part only immersed in the plating solutions. However last time I saw inside a platers (who mostly plate things all over), they weren't set up to do this; the support hooks/power rails were too close to the top of the tank and indeed the tank surface was covered with plastic balls, which presumably prevent too much fume/heat loss from the plating tanks. The balls may interfere with the plating quality on partially immersed objects too for all I know.

cheers

[thatsnotmyname]

Masking is generally the way platers avoid plating areas that don't need to be plated. Lots of different methods used, depending on what the item is. Can be quite time-consuming, depending on what you're plating (or not plating, as the case may be).

[David9694]

So for example you may find that your undercoat works just fine over your etch primer, but causes horrible cracking when the layers are the other way round. This sort of thing can drive you berserk should you have to repair the etch primer coat because you rubbed through it. Ask me how I know this....

Thanks. It seems logical to me to assume that an etch primer will attack a layer of paint it is sprayed onto.

[Brucey]

it may seem logical but it usually has more to do with the chemical make-up of the paint binder, eg cellulose vs acrylic; reactions happen between all sorts of paints not just etch primer and others.

cheers

[wirral_cyclist]

I've worked with printers hard chrome (useless for anything else). Steel needs three plating processes before chrome, a nickel flash coat, an alkali and an acid copper coat before chroming. The balls are croffles and are indeed fume limiters, but they would play havoc with trying to part plate an item, masking is the only way to be sure of limiting the plating area, but it is difficult to do as the plating solution is so damn hot, so adhesive tape isn't reliable as it softens - good PVC gaffer tape last 15 mins max, masking paint is a faff to apply neatly, removal is a pain as it is too soft when hot and tears, oh and cracks and shatters when cold...

[David9694]

it may seem logical but it usually has more to do with the chemical make-up of the paint binder, eg cellulose vs acrylic; reactions happen between all sorts of paints not just etch primer and others.

cheers

Someone scraped my car and I though with all my spraying skills that I could DIY it. I found that the rattle-can spray reacted with the original lacquer.