Bill Pragnell nous apporta ses lumieres en ce 2007/08/30 05:09:
> Alain <ele### [at] netscapenet> wrote:
>> The copper holds well on the silver paint, but nether the nickel nor the chrome
>> will. The copper plating is to thin to help protect from the heat.
> Quite the opposite, probably - Cu is an excellent thermal conductor.
Sure is. And, for exactly that reason, it won't protect the plastic from the 
heat, as in the plating vat, heat comes from all around. Cu will transmit that 
heat quite effeciently to the plastic!
> 
>> Then the nickel makes an exellent bond with the copper, while the chrome will
>> peel from it.
>> Then the chrome will perfectly fuse onto the nickel. Also, the nickel makes an
>> harder, more resilient, substrate.
> Having had a quick peek at the binary phase diagrams, this seems to be
> because Cr is soluble in Ni at low concentrations, and both Cu and Ni are
> soluble in each other to a small degree, whereas Cr and Cu appear totally
> immiscible.
So Ni will bont to Cu, then Cr will bond to Ni, but Cr will not bond to Cu, nor 
will it bond to Ag.
> 
> The silver paint is probably just to give the substrate all-over electrical
> conductivity so it can act as an electrode during the plating process.
Only plausible explanation. The paint's cost comes fron the silver dust it contains.
> 
> Anyway, that's not how I made my styrofoam blob; I used a magic chrome corn
> kernel in a giant popcorn maker. ;-)
> 


-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when your personal correspondence to 
friends starts out with #Dear Linda =
Ken Tyler

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