Lastek 39

No flux on pure copper

Silver solder for joining copper and silver without using a flux.

Requires no finishing after brazing (no fluxresidues that have to be removed).

Lastek 39 cannot be used on nickel or aluminium containing alloys or on steel.

Specifications & Usage


Joining copper in electrical motors, tubes, ...

Refrigeration industry, heating installations, breweries, dairy farms, car radiators, water pipes in the building industry.

Don’t use Lastek 39 for joining copper tubes that contain sulphuric products.

Hardness: ca. 180 HB

Bonding temperature: 680°C (1256°F)

Electrical resistivity: 0.20 ohm.mm²/m


Joint clearance: ± 0.5mm (0.02").

Flux (on brass and bronze): Lastek 31C and Lastek 31CH (powders) - Lastek 31CN (paste).

Preheat with a slightly carburizing flame.

Melt the rod without flux on pure copper.

Bonding temperature: 680°C (1256°F)

Electrical resistivity: 0.20 ohm.mm²/m


Welding proces: Brazing rod
Material Type: Silver solder
Welding positions: PA, PB
Norm : EN 1044
Classification: CP 104 // CuPAg 5 BP
Norm: AWS A5.8
Classification: B Cu-P3
Minimum packing: 1 kg in a cardboard box