Fire Assay Flux

Westref prides itself in supplying geochemical mineral laboratories with high-quality fire assay flux to detect gold and other valuable elements in mineral samples. Our range of flux is made to your specification in our Perth based plant. Is is individually quality controlled in one metric tonne batches which means consistency you can count on. Flux powder is a blend of predominantly dry ingredients that includes litharge, dense soda ash, borax and other ingredients, with a high level of quality control at each stage of production. It comes packaged tailored to your requirements with prompt international shipping. Consultation is available upon request.

  • High level of Quality Control at each stage of production
  • Packaged to your requirement
  • Prompt international shipping
  • Consultation available as needed.

What is Fire Assay Flux?

Flux is a dry reagent used as a key ingredient in the fire assay process. The composition of the flux should be adapted to suit the matrix of the sample being tested. Fluxes are combined with mineral samples containing precious metals and then heated in a furnace to initiate a fusion process precipitating a Lead (Pb) button. Further treatment of this Lead button through the process of cupellation produces a prill containing the precious metals that were present in the original sample. From this point, the assayer can decide on any number of methods to establish a precise breakdown of the precious metals. This method of mineral testing produces results that are so precise they can be specified in parts per billion.

Fire Assay Flux is available with a wide selection of ingredients, although the most common globally are Litharge, Soda Ash, Borax, Baking Flour/Corn meal, Silica Flour and Silver Nitrate. The Litharge is available in both powder and granular form and in different grades of purity to suit your application. Westref will always provide the ingredients to give you the right result at the lowest possible price.

Flux Recipes

Typically, Westref will produce Flux to a very specific, customer-supplied recipe. However, we do have general purpose fluxes available. A commonly referenced product in the industry is F104 which is always kept in stock and is suitable for a wide range of matrixes.


“Reliable, driven, family business that provides quality products and will work diligently with its partners towards mutual success.”

Anonymous customer survey submission, 2016

“I hope you can keep producing such wonderful products and expand the range of your products”

Head of Fire Assay

“We have been using Western Refractories Fire Assay Flux, Crucibles and Cupels for the past six years at our Laboratory in Metro Perth and have had virtually no issues with the quality of the products or timely supply.”

Laboratory Manager Perth, Western Australia

“WR’s level of support, commitment to partnering, response time and desire to constantly improve are exceptional.”

Procurement Lead Perth, Western Australia
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