We’re back with more of your platinum FAQs. Stuller experts Randy Welch and Shane Guidry share their insights. If you missed part one of this series, check it out here.
6. Which sandpaper grit is best for removing dents and scratches from a platinum ring?
360-400-500 abrasive paper
7. When polishing platinum that’s joined to gold, which do I polish first – gold or platinum?
When polishing platinum that is joined to gold, be sure the platinum is polished completely before polishing the gold.
8. Joining Two Platinum Metals
a. Avoid the use of flux when joining Pt alloys. Flux may be used when joining Pt alloys to gold alloys.
b. Platinum iridium to platinum iridium – weld
c. Platinum ruthenium to platinum ruthenium – weld
d. Platinum ruthenium to platinum iridium (10%) – weld.
e. Platinum cobalt (5%) has a lower melt point than PtRu (5%) or PtIr (10%), it cannot be welded to either PtRu or PtIr.
f. Platinum cobalt to platinum cobalt – use 1700C seamless
g. When in doubt, always solder
h. To eliminate the dip in a solder seam use a 1700C seamless solder.
i. Re-tipping - use 14kw cadmium free solder on prong then come back with platinum wire on top of the white solder.
j. If gold is melted into a platinum surface remove the gold with a ball bur and fill it with platinum wire.
9. What does the stamp: IRIDPLAT signify?
This is an older stamp that refers to 900 platinum/100 iridium alloy that was used until the mid 70s. Today, the same alloy is stamped Pt900, 900 Pt or 900 PLAT, as established by the Federal Trade Commission. Platinum Products containing 95/5 platinum alloy may be stamped PLAT.
