New additions and the quality of used metal… Reducing porosity rates will be affected by the amount of new metal used. It is obvious that the greater amount of fresh used, the lower the amount of oxide buildup therefore a lower porosity rate. Reality is additions of 25-50% new metal for most users. When reusing old metal, we suggest some of the following:

      1.) When using Non de-oxidized alloys and melting with opened system, use approximately ¼ teaspoon of flux, borax or a 50/50 borax/boric acid mix. This will help gather the oxides formed, cover the molten metal to protect from absorption and increase fluidity of the metal. Be careful of flux being poured into melt !. Enclosed melting system is not required any flux or Boric & Borax.
      2.) When using de-oxidized alloys and melting with opened system, use only enough flux to gather the oxides formed by the de-oxidizing agents. Usually add the flux by a pinch between ring finger and thumb. Enclosed melting system is not required any flux or Boric & Borax.
      3.) When possible, re-melt old metal to remove investment powder and chemical compounds from de-vesting solutions. Flux melts as necessary and remove this residue flux containing oxide before pouring into shot. Enclosed melting system is not required any flux or Boric & Borax.

When adding fresh additions, it is advisable to maintain a consistent addition of fresh metal, such as 40% each day. White gold will require a higher percentage of fresh metal, such as 50-70% due to the faster oxidation rate by higher melting temperature & prior of melting. We recommend mixing and shotting before casting. These steps allow for the most uniform consistency and control. When fluxing white gold, boric acid is preferable. Double the amount of flux for white gold may necessary by melting with opened melting system.

Note : Flux, Borax and Boric is recommended for opened melting system and may not suitable for closed melting system.