Stained platinum

I'm currently making a platinum ring - all fabricated, no castings. I've
worked with platinum many times and thought I knew what I was doing, so
this came as a surprise. Because the shoulders cover part of the head I
polished part of it prior to fitting them. I first tack-welded the
shoulders at the point where they joined the shank and then started to
solder them where they joined the head. The photo at
http://i106.photobucket.com/albums/m...oldersetup.jpg shows
how the ring was held for soldering. I used hard platinum solder (MP
1450C), but as the solder melted I realised that there was a slight gap
between the shoulder and the head, so I stopped. (I know, I should have
checked before, but in mitigation this is the first time I've used my
new PUK 2 and I didn't appreciate that the metal would move quite as much.)
Anyway, when it had cooled down I noticed the stain on the other side of
the head (the side at the bottom in the first photo).
This photo shows the stain quite well
http://i106.photobucket.com/albums/m...edPlatinum.jpg
It doesn't occur on the side where I started soldering, its on the side
that was nearest the solder pad. The solder pad, which has been used
many times for platinum, is a standard item by GRS. but the jaws of the
holder are made of tungsten.
So, what caused the stain and what's the best way of removing it - its a
slightly brownish colour? The shine is still present, but its stained.
The right hand side, as depicted in the photo, is still pristine.
--
Regards, Gary Wooding
(To reply by email, change feet to foot in my address)

lemel_man wrote:
I'm currently making a platinum ring - all fabricated, no castings. I've
worked with platinum many times and thought I knew what I was doing, so
this came as a surprise. Because the shoulders cover part of the head I
polished part of it prior to fitting them. I first tack-welded the
shoulders at the point where they joined the shank and then started to
solder them where they joined the head. The photo at
http://i106.photobucket.com/albums/m...oldersetup.jpg shows
how the ring was held for soldering. I used hard platinum solder (MP
1450C), but as the solder melted I realised that there was a slight gap
between the shoulder and the head, so I stopped. (I know, I should have
checked before, but in mitigation this is the first time I've used my
new PUK 2 and I didn't appreciate that the metal would move quite as much.)
Anyway, when it had cooled down I noticed the stain on the other side of
the head (the side at the bottom in the first photo).
This photo shows the stain quite well
http://i106.photobucket.com/albums/m...edPlatinum.jpg
It doesn't occur on the side where I started soldering, its on the side
that was nearest the solder pad. The solder pad, which has been used
many times for platinum, is a standard item by GRS. but the jaws of the
holder are made of tungsten.
So, what caused the stain and what's the best way of removing it - its a
slightly brownish colour? The shine is still present, but its stained.
The right hand side, as depicted in the photo, is still pristine.

Well I dont use platinum, but if Ive a stain on anything the first thing
I do is see if its just surface discolouration ie rub on a bit of
cardboard to which youve put some polishing compo.
this will tell you if its something easy to remove or if its gotten
deep into the metal, like firestain does in overheated and underfluxed
sterling silver
as its platinum why dont you put it in some pickle? for cleaning off
fluxes in gold and silver.?
your going to have to do something anyway, so youll have to experiment.
We all have to learn how to find answers to problems which come
upon us in our work. Thats the eal knowhow which you geerally cant find
in books etc.