The vast majority of solders in the world are slurries or mixtures such as 60/40 tin lead solder. They go through a slurry stage as they solidify wherein one component solidifies first and then another. The result is a solder connection rather than a joint. Eutectic solders such as Kesters Ultra pure Tin/lead Silver are in fact excellent because they solidify at a temperature lower than any of the component parts thus they form a solder joint rather than a connection - the key here is the eutectic formula which must be very precise - the solders are obviously different in that they set up with a mirror finish rather than a dull finish, the reason they do this is because they solidify as a unit. The week link in the solders is contamination - the molten solder easily dissolves other metals, this is no problem if you are soldering to a metal that is part of the eutectic mixture (such as tin or lead) you will get contiguous flow right in to the joint (easy to see) but if you solder to a dissimilar metal (such as copper or silver) you will see an obvious dulling at the connection where the eutectic formula fails and and the continuous joint becomes a connection. Cardas Quad Eutectic is tin, lead silver, copper, eutectic. The results are obvious. Most highend products use this solder and other cable manufactures have been using it for over a decade - to them it represents good sound and absolute reliability. - George