PMC Pro – an exciting new material, part IV, soldering

Is PMC Standard really THE most difficult silver clay to solder? If you like challenges, try to solder PMC Pro.

Soldering is inevitable if you want to integrate (semi)precious stones into your pieces. Or even larger CZ stones, because owing to their size and PMC shrinkage, the larger stones often crack the surrounding bezel.
Because of a low melting point of PMC Pro (800°C – as compared to sterling silver: 890 °C or fine silver 961°C) solder with lower flow temperature has to be used.

Silver solder usually comes in the following varieties

Not the melting but the flow temperature of the solder is critical, so with PMC Pro only easy (and, occasionally, medium) solder can be used.
On the other hand, hard solder is superior to easy solder in many ways. Not only it makes stronger bond, it also has a higher silver content. Hard solder is 75% silver, medium is 70%, easy is 65%. Hard solder is recommended for precious metal clay, because it does not soak through the porous silver surface as easily. PMC Pro might be one of the densest precious metal clay types, but it is still porous as compared to cast silver. The other reason of solder erosion through the surface is the overheating of solder, which, obviously, is more likely to happen with low-temp solder. I don’t really understand why ‘easy’ solder is called so: it is not easy at all, especially every time the bond turns out to be a ‘false flux bond’ and the solder just ‘escapes’.

So now you understand why soldering PMC Pro is such a tricky balance “between the devil and the deep blue sea”.

Maintaining the right temperature is the most challenging part of soldering PMC Pro to sterling silver parts, such as bezels. And – funny enough – soldering larger pieces is easier because they do not heat up as quickly as smaller pieces.

This experience has shown that soldering PMC Pro is possible, but it has some constraints. Overheating and burning PMC Pro elements, as well as solder erosion through the surface and weak bond remain the biggest problems. Tricky soldering is probably one of the factors that limit the popularity of PMC Pro.