Thanks Guys! This is good and important information. I will probably go
ahead and put my 'new' bumper guards in service and not be surprised when the
chrome starts to peel. I also will not give him any of my spare bumpers to
re-chrome!
> Date: Mon, 15 Jun 2009 15:36:27 -0400
> From: dmscheidt@gmail.com
> To: tr3driver@ca.rr.com
> CC: shop-talk@autox.team.net
> Subject: Re: [Shop-talk] (no subject)
>
> On Sun, Jun 14, 2009 at 11:59 PM, Randall<tr3driver@ca.rr.com> wrote:
> >> thus the copper isn't needed unless
> >> the metal is badly pitted.
> >
> > What I was told, long ago, was that it is very difficult to get nickel to
> > bond properly to steel. B If it's not done just right (some claim it's
> > impossible), then the resulting chrome will eventually peel. B Maybe not
> this
> > year, maybe not next, but it will peel.
> >
> >> B They then leave the piece in the nickle for about
> >> 45 minutes, vs the usual 5-10.
> >
> > Sounds kind of haphazard. B For a quality job, there should actually be
two
> > separate layers of nickel, done under slightly different conditions. B I
> > forget the details offhand, but it has something to do with preventing
> > dissimilar metal corrosion. B Without the two layers, the part is more
apt
> to
> > rust. B Supposedly the nickel is what provides the corrosion resistance
and
> > much of the 'shine', the chrome just improves the appearance of the
nickel
> > and keeps it from tarnishing.
>
> Well, it depends on what you're plating, and why. For something like
> a bumper, where you're after the shine, the best process is
> copper-coat the bare part, polish the copper to mirror smoothness,
> then two layers of nickel, followed by a very thin layer of chrome.
> The copper fills the surface of the part, and more readily takes a
> polish than steel. The two layers of nickel are called bright and
> semi-bright. I think, but can't remember, that the semi-bright goes
> first. The bright nickel is a sacrificial coating (galvonically), and
> spreads the corrosion forces laterally, instead of through the
> coatings.
>
> for a part that's covered in what's called "hard chrome", where the
> chrome is a wear preventing surface, there's a slightly different
> procedure. (Gun barrels and chambers, hydraulic cylinder bores and
> pistons, and the swivel balls of elderly Land-Rovers (LBC content!)
> are all hard chromed.) The surface is prepared; typically that
> involves grinding it smooth, but sometimes some texture is put into
> it, if it's supposed to have it (to keep a film of oil, say). Then
> the two (or sometimes three) layers of nickel are put on, followed by
> a very much thicker layer of chrome. These parts aren't usually super
> shiney, though they can be, if that's useful property.
>
> A part with only one layer of nickel might well look wonderful, but it
> won't stay that way.
>
>
> >> Is there any good
> >> way to tell the quality of a re-chroming job?
> >
> > Not that I know of.
> >
> > Randall
> > _______________________________________________
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>
>
> --
> David Scheidt
> dmscheidt@gmail.com
> _______________________________________________
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