Flux:  Which one is right for your project?????


Question #1:   Is flux going to be used in a Coal or a Gas forge?

Many coal forge fluxes have iron filings in them. Just as your mig wire is designed to aid in the weld, so too is the iron in the flux.   However, those same iron pieces can adhere and shorten the life of the insulation in gas forges.  Most fluxes designate which type of forge it should be used with (gas or coal) for this reason.

Question #2:  Can a gas forge flux be used in a coal forge?

Yes.  Although not necessarily designed for or fully tested in a coal forge it will weld pieces together providing the material is up to welding temperature.

Question #3:  Can a coal forge flux be used in a gas forge?

Yes.  If there is metallics in the flux it would be bad for the insulation material in a gas forge.  But it will weld.

Question #4:   What are you forge welding?

The same metallics that harm your gas forge liners will leave spot that can show out on that beautiful Damascus knife you just cleaned up.  If you will not be shining up your piece, the iron will make the welding process easier though.

Question #5:  Modern Chemicals or Old school fluxes?

Forge Welding Flux, like hammers, can be a very personal thing.  I’ve been forging for over 40 years and have been forge welding for almost as long.  When I first started welding I was not allowed to use flux. I had to learn to listen for that crackle.   It was all about getting to that perfect temperature and not about the fairy dust that could be sprinkled on.   Years later and when my father’s back was turned, I tried many of the borax based fluxes.  Most of those fluxes today are manufactured by Superior flux’s Anti-Borax brand. I also tried items that were even more readily available like mud daubers nests, sea salt, beach sand…..and the list goes on.  We definitely have a lot more choices today.   The chemists have been at play.  Modern does seem to be better, requiring less sprinkled on and better flow, but modern comes with a bigger price tag.   Hopefully ease of use and efficiency make the cost more palatable.

Below is the list of Fluxes we carry and a little bit about each one:

Iron Mountain Flux (16oz.) – Most popular – Contains Iron Filings - A Modern chemical composition that flows better than most other fluxes.   Due to its popularity, it can be seen used in many YouTube videos.

White Mountain Flux (16 oz.) – Very Popular – No Iron Filings – Same as its sister above but minus the metal, which makes it the choice for welding Damascus billets.

Z-Weld – (1 lb.) – No Iron Filings – Gas Forge Flux - Discontinued (but still in stock) - Sodium Tetraborate – Modern formulation, which is well accepted, but chemical has become very hard to get.

Anhydrous Borax (1 lb.) – Depot Flux - no iron filings – just plain borate of sodium with nothing added.    Anhydrous = moisture removed

Boric Acid (1 lb.) – no iron filings – Just plain hydrogen borate or boracic acid.  Another cleaning agent that works well for forge welding and is not too hard to get.

EZ-Weld Forge Flux (1 lb.) – contains iron filings – Ez-weld. Cherry-weld, and Climax Flux are identical...except for the label - adheres to ferrous metals at relatively low heat, and is equally good for lap, split, butt, or jump welding. This flux compound enables the blacksmith to weld tool steel, plow open hearth and Bessemer steel at relatively low temperatures making stronger, smoother welds. The flux’s high percentage of metal (about 40%) facilitates the forge welding process considerably. EZ-Weld forge flux can be used with both iron and steel.


Stableweld Forge Welding Flux (1 lb.) – contains iron filings - has a lower (12%) metal loading than the EZ-Weld. This forge flux is used in forge applications that require a lower metal concentration in the flux. Stableweld functions like EZ-Weld in most forge welding processes and can be used in a wide variety of applications.


Forge Borax (1 lb.) – no iron filings - contains no water of hydration and melts smoothly at 740°C /1350°F. The flux promotes deep penetration of the filler metal in the joints, resulting in high bond strength. Forge Borax removes oxides rapidly and thoroughly without bubbling, keeping impurities and porosity out of the joints.


Crescent Forge Welding Flux (1 lb.) – no iron filings - serves as a substitute for Borax on fine work forgings. Crescent Forge flux contains no metal filings and thus cleans easier. It is used in applications such as finishing heats, toe caulk and plow work.


Now that we are all thoroughly confused.  Below is a chart that might help.