Sputtering gold

lathmach

In a recent thread there was discussion concerning the possible "lasering" of proof gold coins.
The use of lasers on metal I have seen has been for cutting, welding, and blasting holes.
I felt this form of laser could not be used to smooth the surface of a coin, as it has a cratering effect.
Mark Feld made a comment that he had seen examples of coins that had been lasered, and they had a somewhat wavy surface finish.
I used to have gold plating done on aluminum extrusions that were used as reflectors in dental equipment and this got me thinking.
What has possibly been tried on proof gold coins is actually a plating process known as sputtering.
This is how silver or aluminum is plated to glass in the manufacture of mirrors.
This may be something to investigate further online, for those of you more computer savvy than I.

Ray

Bayard1908

What you're calling sputtering, I believe is better known as physical vapor deposition.

Bear

Technology advances, for good or ill.

tincup

I'm not sure if PVD can be used to smooth gold surfaces. This is the process that is used to put dark coatings on knife blades, etc; hardening of surfaces, etc. But can it be controlled to a very localized area such as would be needed to 'smooth' out a rough surface on a gold coin? (I have very little knowledge of this process, and can only speculate whether the process can be used for this purpose or not).

coinguy1

<< <i>In a recent thread there was discussion concerning the possible "lasering" of proof gold coins.
The use of lasers on metal I have seen has been for cutting, welding, and blasting holes.
I felt this form of laser could not be used to smooth the surface of a coin, as it has a cratering effect.
Mark Feld made a comment that he had seen examples of coins that had been lasered, and they had a somewhat wavy surface finish.
I used to have gold plating done on aluminum extrusions that were used as reflectors in dental equipment and this got me thinking.
What has possibly been tried on proof gold coins is actually a plating process known as sputtering.
This is how silver or aluminum is plated to glass in the manufacture of mirrors.
This may be something to investigate further online, for those of you more computer savvy than I.

Ray >>

Ray, for the record, in my recent posts on the subject, I didn't describe the appearance of the lasered proof gold coins I had seen. You are probably thinking of the post I have included below from WTCG/Wei.

"At the next big show look for proof gold coins housed in "third world" holders and odds are those coins were lasered or altered in some way or another.

Proof gold coins that have had their fields lasered will have fields that bear a "watery" look, as if there are ripples or tiny waves . An unlasered proof gold coin should have smooth fields. By the devices such as the stars there could be a "halo" near where the raised devices meet the fields. Lasered surfaces will also have a tendency to haze over after time."

keets

what about Orange Peel??

PerryHall

<< <i>what about Orange Peel?? >>



Agree. I thought proof gold was supposed to have watery surfaces commonly refered to as the orange peel effect.

coinguy1

<< <i>

<< <i>what about Orange Peel?? >>



Agree. I thought proof gold was supposed to have watery surfaces commonly refered to as the orange peel effect. >>

"Watery surfaces" and "orange peel effect" are not necessarily synonymous. Many, if not most proof coins exhibit watery surfaces, but many of them don't display an "orange peel" texture.

Edited to add: Look at the upper/darker part of the reverse image of the coin below and and you should see the "orange peel effect". The obverse, which according to the auction description, did not display "orange peel", looks watery in appearance. Again, "orange peel" and "watery" don't mean the same thing.

EagleEye

The Orange peel found on gold and copper coins comes from the high annealing temperature the planchets were subjected to. The were heated to the same specs as silver, which was too high for gold and copper. The planchets were crystallized because of the higher temperature. On Proof pieces with deep mirrors the crystallization is very evident.

If the surface of these gold and copper proofs are altered it will be very evident. You'll see a melted or flat area where there should be a "Orange peel" look.

coinguy1

<< <i>The Orange peel found on gold and copper coins comes from the high annealing temperature the planchets were subjected to. The were heated to the same specs as silver, which was too high for gold and copper. The planchets were crystallized because of the higher temperature. On Proof pieces with deep mirrors the crystallization is very evident.

If the surface of these gold and copper proofs are altered it will be very evident. You'll see a melted or flat area where there should be a "Orange peel" look. >>

Rick, I agree that if a proof gold coin with orange peel surfaces is lasered, it should be evident IF the coin is examined very carefully. However, there are many proof gold coins without the orange peel texture and if they are lasered, it should be much more difficult to detect.

Hyperion

Great, now we have watery vs. sputtery.