Brazing alloy on the basis of copper for the connection of copper, brass and bronze.
Lastek 391 is especially recommended where careful preparation of the joint is not possible (large or unevenly shaped gaps, overhead welding, …).
The melting characteristics are such that the operator has complete control of the weld pool.
On red copper Lastek 391 can be used without flux.
For brass, cast copper, tin-copper alloys: use flux.
Recommended for cold and hot water systems, cooling systems, sanitary and electrical applications.
Not suitable for gas pipes or for soldering steel. Here you can use Lastek 31, Lastek 32, Lastek 34, ...
For joints that are subject to fatigue (e.g. cable connections on vibrating transformers, rotating electric motors, etc.), the use of Lastek 38 or Lastek 39 is recommended above Lastek 391.
Bonding temperature: 690 °C (1274 °F)
Electrical resistivity: 0.25 ohm.mm²/m
Flux: Lastek 31CH (powders) - Lastek 31CN (paste).
Preheat with a slightly carburizing flame.
If the solder does not run around in the seam by itself, then add at different places.