[DeTomaso] Powdercoating Campi rims

[MikeLDrew at aol.com]

In a message dated 9/23/15 11 49 14, michaelsavga at gmail.com writes:


> I have heard that real magnesium wheels ( like ours ) do not fair well in 
> a
> powder coating oven,
> something about the heat after all these years making them even more
> brittle,
> 
>>>You're confusing several conflicting ideas.

Our wheels often don't do well in powdercoating because they have tiny 
cavities filled with gas, and when the wheel is first painted and then heated, 
the gas expands and creates bubbles in the paint.

Some people claim that magnesium wheels become brittle with age (although I 
have never, EVER heard of a Pantera wheel failing due to that, so I chalk 
it up to urban legend).   However, years ago Jack and I wrote an article 
about the care and feeding of such things, and Jack asserted that they can be 
returned to like-new condition by annealing them.   This involves heating them 
up in an oven (like a powdercoating oven) and then allowing them to cool 
slowly.

So if you want to powdercoat wheels, first you strip them, then put them in 
a powdercoating oven at the end of the day; this heats them up to full temp 
and then they cool down overnight.   Then they can be powderpainted in the 
morning, and put back in the oven in the normal fashion to bond the 
powderpaint to the wheel.

Garth Rodericks has done a magnificent job of powdercoating his own wheels 
using a kit (from Eastwood I think?) and an old kitchen oven.


> >I would simply clean them , maybe strip them, spray them with Argent 
> Silver
> and then a clear coat.
> 
>>>That's generally what I advocate too, except you can't just strip them 
and paint them silver.   The unique characteristics of magnesium require much 
additional care.

Ford issued a bulletin to the dealers advising them that the standard Ford 
Argent Silver was a suitable color, but I don't really believe that's 
true--I think the Ford color is too bright.   

The code is PPG3822C, which corresponds to Ditzler DX8555.

Campagnolo made the OEM wheels for all the Italian marques (Ferrari, 
Lamborghini, Abarth, Maserati etc.) and I think they only had a handful of stock 
colors (silver, gold mostly).   

The original magnesium wheels were first painted with a zinc chromate green 
primer/sealer, then painted silver atop that.   If they strip the wheels to 
metal and just paint them without the zinc primer, corrosion could well set 
in and the paint might fail.   

If you really wanted to go crazy, after the wheels were stripped to metal, 
you would need to ship them off to have them Dow 17 anodized (Google it), 
then painted with zinc chromate primer, then silver.

You can spend days reading about this stuff on Ferrari forums.   Those guys 
go crazy trying to replicate the original paint hue and finish, and often 
fail and have to do them again and again to get it right.

The stock primer is pretty tough stuff.   If you are going to have them 
strip the paint off, perhaps they can do so in a manner that leaves the green 
coating underneath?   But failing that, I would definitely urge that you seal 
the wheels properly with zinc chromate (again, this is based on both the 
factory's original technique, and what I've read on these various Ferrari 
forums, learning from the mistakes of others....)

Mike

-------------- next part --------------
   In a message dated 9/23/15 11 49 14, michaelsavga at gmail.com writes:

     I have heard that real magnesium wheels ( like ours ) do not fair
     well in a
     powder coating oven,
     something about the heat after all these years making them even more
     brittle,

   >>>You're confusing several conflicting ideas.
   Our wheels often don't do well in powdercoating because they have tiny
   cavities filled with gas, and when the wheel is first painted and then
   heated, the gas expands and creates bubbles in the paint.
   Some people claim that magnesium wheels become brittle with age
   (although I have never, EVER heard of a Pantera wheel failing due to
   that, so I chalk it up to urban legend).  However, years ago Jack and I
   wrote an article about the care and feeding of such things, and Jack
   asserted that they can be returned to like-new condition by annealing
   them.  This involves heating them up in an oven (like a powdercoating
   oven) and then allowing them to cool slowly.
   So if you want to powdercoat wheels, first you strip them, then put
   them in a powdercoating oven at the end of the day; this heats them up
   to full temp and then they cool down overnight.  Then they can be
   powderpainted in the morning, and put back in the oven in the normal
   fashion to bond the powderpaint to the wheel.
   Garth Rodericks has done a magnificent job of powdercoating his own
   wheels using a kit (from Eastwood I think?) and an old kitchen oven.

     >I would simply clean them , maybe strip them, spray them with
     Argent Silver
     and then a clear coat.

   >>>That's generally what I advocate too, except you can't just strip
   them and paint them silver.  The unique characteristics of magnesium
   require much additional care.
   Ford issued a bulletin to the dealers advising them that the standard
   Ford Argent Silver was a suitable color, but I don't really believe
   that's true--I think the Ford color is too bright.
   The code is PPG3822C, which corresponds to Ditzler DX8555.
   Campagnolo made the OEM wheels for all the Italian marques (Ferrari,
   Lamborghini, Abarth, Maserati etc.) and I think they only had a handful
   of stock colors (silver, gold mostly).
   The original magnesium wheels were first painted with a zinc chromate
   green primer/sealer, then painted silver atop that.  If they strip the
   wheels to metal and just paint them without the zinc primer, corrosion
   could well set in and the paint might fail.
   If you really wanted to go crazy, after the wheels were stripped to
   metal, you would need to ship them off to have them Dow 17 anodized
   (Google it), then painted with zinc chromate primer, then silver.
   You can spend days reading about this stuff on Ferrari forums.  Those
   guys go crazy trying to replicate the original paint hue and finish,
   and often fail and have to do them again and again to get it right.
   The stock primer is pretty tough stuff.  If you are going to have them
   strip the paint off, perhaps they can do so in a manner that leaves the
   green coating underneath?  But failing that, I would definitely urge
   that you seal the wheels properly with zinc chromate (again, this is
   based on both the factory's original technique, and what I've read on
   these various Ferrari forums, learning from the mistakes of others....)
   Mike