Silver Solder Extra Hard 1540^oF (IT Solder)

This is one piece of Extra-Hard Silver Solder weighing approximately 5 Pennyweights (5 DWT-or 1/4 troy ounce). This silver solder is used for hard (torch) soldering (brazing) only.  The flow temperature of this solder is 1540^o F (838^oC) This solder contains silver (75%), copper (23%) and zinc (2%).

Because this solder has such a high flow point, it can be refered to as an IT solder for use on findings being enamel fired.  You can use this solder to solder findings onto pieces to be enameled before the pieces are to be enameled. Since the enameling firing temperature is below the high 1540^oF flow point of this Extra Hard Silver Solder, the soldered findings will remained soldered.  If enamel comes into contact with this or any other zinc bearing solder, the enameling may bubble. Because this solder contains Zinc, it is not an eutectic solder.  Eutectic solders are used during enameling to avoid bubbling if there is a high chance that the solder will come in contact with the enamel. Eutectic solders contain silver and copper only.

The terms Extra Easy-Easy-Medium-Hard are used to describe the relative temperature flow points between one type or more specifically, one brand of hard solder.  Extra Easy will have a lower flow point than Easy, which will have a lower flow point than Medium, which will have a lower flow point than Hard.  Extra Hard will have the highest flow point.  This labeling system generally holds true for all brands of silver solders, but there are differences between manufactures, so you could find one makers Medium flows at the same time another makers Hard will flow.  Generally, the higher the flow point temperature, the higher the silver content of the solder.  The higher the silver content of a silver solder, the better the solder will match the color of the silver, and theoretically, the stronger the bond.

What temperature solder should you use?  If you are manufacturing, use the highest temperature (Hardest) solder you can so repairs may be made later with lower temperature solders.  If you are doing repairs, use the lowest temperature (Extra Easy) solder you can, since you don't know what was used before.

Here are the flow points and silver content of Otto Frei's Silver Solder:

• 804-404 1300^oF (705^oC) Extra Easy 
• 804-405 1325^oF (719^oC) Easy 
• 804-406 1390^oF (755^oC) Medium 
• 804-407 1475^oF (802^oC) Hard 
• 804-408 1540^oF (838^oC) Extra Hard