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Re: soldering platinum
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Posted by Daniel E. on December 16, 1998 at 23:42:13:
In Reply to: Re: soldering platinum posted by J Dungey on December 15, 1998 at 06:01:58:
Let's put it this way--if a client wanted me to do what you are considering doing, I would turn down the job in a heartbeat.
The reason has to do with the flowpoints of the materials involved--platinum is 2000 to 3000 degrees F.; silver is 1600 to 1700 degrees F. Any solder alloy which would bond to the platinum sufficienty well would need to be brought up to temperatures so high as to puddle the silver. There is a technique called "investment soldering", but since the brooch has sentimental value, I would hesitate to take the risk.
You can use a medium silver solder (flowpoint of around 1100 to 1300 degrees F.) This would minimize the danger to the silver elements--you will need to HEAVILY scuff the platinum at the points of the joint. However, this type of solder joint will be fragile at best because the solder never really makes a molecular bond w/the platinum, but only sticks to the surface; in addition, over a relatively short period of time, the silver solder will darken, revealing the joint