Brompton 'Lacquer' Finishes

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LiveFree
Posts: 16
Joined: 25 Mar 2019, 3:57pm

Brompton 'Lacquer' Finishes

Postby LiveFree » 11 Aug 2019, 10:43am

Hello all-

I am hoping that you might be able to advise about something- I know that there have been a fair few stories of the raw lacquer (clear powdercoat) finished Bromptons having problems with surface rust/other blemishes appearing- even on bikes that are not so old; but I am wondering about the new 'flame lacquer finishes'- would these also run a similar risk of rust/blemishes appearing/showing?

And equally, are these fancy 'lacquer' finishes more difficult to deal with in terms of touching up chips/scratches etc than something like the standard black Brompton? I can see that with the matt black finish (although not as useful at hiding blemishes as gloss finishes) if any touch up work needs to be done (and by the virtue of it being a folding bike, I think the chance of that is quite high!) it shouldn't show too much; whereas with the flame lacquer I can imagine it would really stand out. I would be interested to hear other people's experiences/opinions- I think that the black Brompton, whilst not as aesthetically pleasing to me as the flame/raw lacquer, for a folding bike being kept in the long term might be a better bet than the fancy finishes.

Any input from others would be gratefully received :D

AndyA
Posts: 386
Joined: 21 Mar 2009, 9:16pm
Location: Edinburgh

Re: Brompton 'Lacquer' Finishes

Postby AndyA » 11 Aug 2019, 8:15pm

I think this sort of corrosion/blemishing happens under all kinds of powdercoat and it's only visible on the clear powdercoat frames. I don't think it will be as visible under the flame lacquer as the clear, the flame lacquer is close to rust in colour! I'm certain it would be a pain to touch up. That said, it would be the colour I'd choose. Or maybe purple

alexnharvey
Posts: 725
Joined: 10 Jan 2014, 8:39am

Re: Brompton 'Lacquer' Finishes

Postby alexnharvey » 12 Aug 2019, 12:13pm

Rust spiders are a feature now, rather than a bug.

LiveFree
Posts: 16
Joined: 25 Mar 2019, 3:57pm

Re: Brompton 'Lacquer' Finishes

Postby LiveFree » 12 Aug 2019, 12:17pm

Many thanks Andy- what you said makes total sense. Alexnharvey- I'm afraid I didn't quite understand your response: could you please explain it? Thank you :D

alexnharvey
Posts: 725
Joined: 10 Jan 2014, 8:39am

Re: Brompton 'Lacquer' Finishes

Postby alexnharvey » 12 Aug 2019, 12:32pm

LiveFree wrote:Many thanks Andy- what you said makes total sense. Alexnharvey- I'm afraid I didn't quite understand your response: could you please explain it? Thank you :D


Rust spiders is a term for the filigree rust patterns that develop under the lacquer. I think they're inevitable with these finishes, so if you want that look you accept them.

http://groovycycleworks.blogspot.com/20 ... f.html?m=1

LiveFree
Posts: 16
Joined: 25 Mar 2019, 3:57pm

Re: Brompton 'Lacquer' Finishes

Postby LiveFree » 12 Aug 2019, 1:05pm

Aha, many thanks Alexnharvey- now I get you. Cheers for that- again, good information to have :D

Brucey
Posts: 34868
Joined: 4 Jan 2012, 6:25pm

Re: Brompton 'Lacquer' Finishes

Postby Brucey » 12 Aug 2019, 1:22pm

its more usually known as 'filiform' corrosion I think.

Its worth comparing the performance of clear coating in other applications, e.g.

1) on top of other paint finishes. They have got this sorted out now, but a few years ago every change in paint chemistry made for a new, improved risk that the clear coat would just fall off the underlying paint. Very nasty.

2) On alloy car wheels, eg on top of turned aluminium finishes . Doesn't last that long; a couple of UK winters is often enough to cause the finish to go white and crusty under the edges of the clear coat. A whole industry exists for refinishing alloy wheels and this is a good part of the reason why.

3) over bare steel. At best it works about as well as any other coating that isn't properly chemically bonded to the metal surface, and hasn't got anything in it to retard the corrosion process. i.e. not very well.

Crummy paint finishes may well have filiform corrosion beneath them (often you can see this raised 'veins' in the paint surface), but most good paint finishes don't. A good wet paint system ought to comprise a passivation treatment, an etch primer, an undercoat that resists corrosion (e.g on steel containing zinc) and then further colour coats before the clear coat. The multiple coats give the paint finish the overall combination of properties that is desired.

You can do a pretty good job with a two-coat powder coat too but the overall finish is thicker and less smooth overall, so isn't the best way with steel frames which have delicately filed lugs; the definintion is lost, and the hours of work by the framebuilder is wasted.

Overall verdict; clear coat direct on steel is a load of nonsense, for looks over anything else. It is only going to last if you ride/store your bike in bone-dry conditions.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

LiveFree
Posts: 16
Joined: 25 Mar 2019, 3:57pm

Re: Brompton 'Lacquer' Finishes

Postby LiveFree » 12 Aug 2019, 2:35pm

Great information- thanks Brucey :D I'm not sure if Brompton's clear powdercoats count as being painted directly on bare metal exactly- their solution to this seems to be to pre-treat the frame with an iron phosphate coating, to prevent any corrosion occurring under the clear coat. In practice though, from what I've seen- this doesn't seem to be a sufficient solution, as there seem to be more than a few of the 'raw lacquer' Brommies about with filigree rust showing.
It does indeed seem that the clear powder-coated Bromptons are a case of form over function! Good for anyone thinking of buying one to know :o