Updated: Feb 21, 2022
Some strange things happen to the metal as you solder. It happens in stages; some of the changes are very subtle. Look for the subtle change. This happens just at the temperature that the surface of the metal will start to melt. The metal gives off an ion cloud of charged particles. The cloud is a plasma that admits an orange glow.
When you see the glow coming from the metal and you see the surface start to shine, that’s the maximum temperature before every thing melts. You must assume that your solder has melted at that temperature because the solder melts at a lower temperature than sterling silver.
What Is Plasma?
Plasma is superheated matter – so hot that the electrons are ripped away from the atoms forming an ionized gas. It comprises over 99% of the visible universe. In the night sky, plasma glows in the form of stars, nebulas, and even the auroras that sometimes ripple above the north and south poles. That branch of lightning that cracks the sky is plasma, so are the neon signs along our city streets. And so is our sun, the star that makes life on earth possible.
Plasma is often called “the fourth state of matter,” along with solid, liquid and gas. Just as a liquid will boil, changing into a gas when energy is added, heating a gas will form a plasma – a soup of positively charged particles (ions) and negatively charged particles (electrons).
Solder is a mixture of three metals: silver, copper, and zinc. This mixture is called an alloy.
Solder comes in three different alloys: Extra Easy, Easy, Medium, and Hard and Extra Hard. Each one has different melting point.
Extra Easy 1207F / 653C
Easy 1325F / 719C
Medium 1660F / 738C
Hard 1450F / 788C
Extra Hard 1490F / 810C
The solders melting point can be changed by improper heat application. The zinc and copper can be depleted from the solder before they flow. The Zinc and copper can be absorbed into the sterling silver. This can happen by holding the temperature elevated just below point for too long; Or by multiple heating and cooling the piece. The zinc can migrate into the Sterling causing a change in the melting point of the solder. Applying the heat directly to the solder will also overheat it causing the zinc in the solder to evaporate and the copper in the solder to oxidize. This destroys the properties of the solder causing it not to flow properly.