Jensen solder

In general, Jensen recommends the highest melting presolder that can work with any given alloy.  For example, the recommended pre-solder for Sentry is PWS.  Sentry has a solidus temperature of 1190°C, PWS has a liquidus temperature of 1150°C, leaving the technician about 40 degrees between the temperature that the solder will start to flow and the temperature that the casting will start to melt.

Using the highest melting presolder gives you a technical advantage, in that your pre-soldered frames will be less likely to warp or distort during oxidation and opaque firings.  Generally speaking, higher melting range solders will be more resistant to creep than lower melting solders.

However, some technicians (particularly those who solder infrequently) may need a larger “window” between solder liquidus and alloy solidus.  If you have difficulty getting the solder to flow, you can usually use a lower melting solder.  In the case of Sentry, you can easily use P80 solder which is completely molten at 1115°C.  You’ll then have a “window” of 75°C between the temperature where the solder starts to flow and the temperature where the casting starts to melt.  You may give up a little theoretical creep resistance in the framework, but it’s easier to get the solder to flow.

Our LX solder is a noteworthy product that deserves special mention.  LX stands for “Low expansion” – the CTE of the solder is much, much closer to that of PFM casting alloy than most pre-solder formulations.  LX is great for repairs, and those frameworks where the joint gap is a little too wide for comfort.  Often times when a technician solders a large repair or a wider-than-ideal gap with a conventional pre-solder, they find the high CTE of that solder causes cracks in the porcelain during subsequent veneering.  LX virtually eliminates porcelain cracking around wide joints and large repairs.  It’s a lifesaver product that most technicians should have in the drawer in case of emergencies.  LX has a similar melting range as Spirit solder, and in most cases can be substituted entirely for Spirit, but it does not flow quite as readily as Spirit so some technicians choose to use Spirit for routine soldering of alloys like JP-I, Advantage and Stability, and use LX only for larger repairs and joints when the ceramic may be effected by a large mass of solder on the framework.

Download: Pre-Solder Guide

Download: Post-Solder Guide