Platinum and gold - a string of questions

[ajda]

I was planning to use white gold wire to make a kind of stitching effect on gold sheet. Now I'm wondering if platinum wire might be a better option. But not knowing much about it I have a few questions:
1. I assume platinum would be significantly more durable than white gold - is that right?
2. Cooksons seem to sell it no thinner than 0.5mm - would it be easy enough to draw down, to say, 0.3 or 0.2mm?
3. What do I need to be aware of when working with platinum for the first time? I've read that it's is more ductile but less malleable than gold, that it anneals at a higher temperature, that it is susceptible to cross-contamination from tools that have been used with other metals - but I have little idea of what all this might actually mean in practice...
4. For soldering platinum to gold, what type of solder would be recommended? The platinum is 950, I believe, and the gold would be 750 red.
5. Hallmarking: the platinum "stitches" would probably too thin to take a mark and the total quantity used would be very small in any case (ie less than the 0.5g threshold for platinum). As far as I can understand from the LAO guidance, they'd probably mark the gold part and not put any mark on or for the platinum - is this correct?

Alan

[china]

Others will be able to elaborate more on this I am sure although I will pass on what I know.
1 Yes because it is harder, also does not require plating.
2 Don't see why not.
3 It is less malleable, Gold is most malleable of all non alloy's, more ductile? yes it anneals at a higher temperature, also solders at higher temperature, cross contamination is a concern with all precious metals if I don't have duplicate tools I make sure to clean them between metals
4---?
5 Don't have this problem in Australia so I can't comment

[ps_bond]

It's ductile, but quite tough on tools. Drawing it down works; I like my carbide drawplates for it *but* you can also buy platinum laser welding wire which is around the 0.25mm mark IIRC.

There's a Johnson Matthey pdf around called "An Introduction to Platinum"; it used to be available on the London Assay Office site, but I can't see it there at the moment. Well worth a read. You might find it with some googling, but I'm not sure why it has disappeared from the net virtually everywhere.

I'd use 750 red gold solder - the mp of Pt solder is too high for your gold and the colour difference is not a problem. Actually, that's a lie - I'd laser the thing :)

Some links -
http://www.ganoksin.com/borisat/nenam/fearless-platinum-repairs.htm
http://www.ganoksin.com/borisat/nenam/joining-platinum.htm
(Plenty of others around too)

[ajda]

Thanks, both - useful links, Peter. I think I've found the Johnson Matthey intro here - http://www.jmny.com/technical/platinum-manual

Alan