Flux - Thessco
The Thessco Group is one of the world’s largest manufacturers of Silver Brazing Alloys, Metal Joining Products and Industrial Silver Alloys.
Thessco Group, Silver Brazing Alloys, Metal Joining Products, Industrial Silver Alloys
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The correct choice of flux is the key to good brazing practice and many problems arise from the incorrect selection or ineffective application of flux. A good match between the flux and the brazing alloy/parent metal combination is essential if strong, sound joints are to be produced.

The flux layer performs the critical function of cleaning and protecting the surface of the parent metal during brazing, and so facilitates the ‘wetting’ and flow of the brazing alloy.

Not only is it important that the proper flux is selected, but also that sufficient flux is applied to the joint area to provide protection throughout the brazing cycle. A further benefit is, that if excess fluxis applied in the immediate joint area, oxidation of adjacent surfaces may be prevented, so reducing post-brazing cleaning costs.

As a guide, the flux selected should be active at least 50°C below the solidus and 50°C above the liquidus of the brazing alloy selected.

Our range of fluxes is available as either powder or paste in a range of packaging. Please consult your Sales Office for technical support.

Specialist fluxes are available for specific customer requirements.

Table 5

Range (°C)
General Purpose
Y550-750GoodHighMediumPowder & Paste
U600-800GoodHighMed/LongPowder & Paste
F650-850ModerateModerateLongPowder & Paste
Special Application
B750-1000ModerateModerateVery LongPowder
HT750-1200ModerateModerateVery LongPowder
U4 (Gas Application)550-800Very GoodMediumMediumPaste
H1R550-880ModerateModerateVery LongPaste
H35R700-1000GoodMedium/HighVery LongPowder & Paste
Al 5530-600ModerateMedium/HighMediumPowder
F670200-400Very GoodHighMediumLiquid
E550-800GoodHighVery LongPowder