Questions and Answers
Technical
Annealing and soldering
Casting
Degreasing and rinsing
Polishing and finishing
How to distinguish between Argentium Sterling and standard sterling
Health and Safety
Technical
Annealing and soldering
Q1. Are there differences in annealing Argentium 930 Silver in comparison to standard sterling?
A. Argentium 930 Silver shows a paler red glow at annealing and soldering temperatures, in comparison to standard sterling silver. To prevent overheating the silver, it is recommended to carry out annealing and soldering operations in a shaded area, which makes it easier to see the pale red colour. The recommended temperature for furnace annealing is 1100°F/595°C.
Q2. How can sagging be prevented in Argentium 930 Silver sheet , during high temperature heating applications?
A. Sagging can be prevented by an initial low temperature anneal. Make sure the sheet is well supported and heat evenly with a large flame to a pale red annealing temperature, then air-cool to room temperature.
A. Use lower temperature solders whenever possible.
Q3. Why has my Argentium 930 Silver cracked after quenching?
A. Argentium 930 Silver cools slower than standard sterling silver after heating operations. It is important to wait until any red heat has disappeared before quenching.
Q4. Argentium 930 Silver cracked when I moved it during soldering - how can this be prevented?
A. It is important not to move or manipulate Argentium 930 Silver at red-hot temperatures as the silver may crack. Simply make sure that your piece is well supported during soldering and annealing operations and wait for any red heat to disappear before touching your piece.
Q5. Do you need to apply flux to the whole piece of work during soldering applications?
A. No, it is only necessary to apply flux to the solder seam. Argentium Silver alloys benefit from being heated in air, as this promotes the formation of the protective germanium oxide at the surface.
Q6. Flux has caused a stain on Argentium Silver, how can this be prevented?
A. We would advise using a different flux. MY-T-FLUX (supplied by Rio Grande), Prip's flux and Battern's flux have been recommended for use with Argentium Silver by our customers.
Q7. What could be the cause of firescale after annealing Argentium Silver?
A. Soldering or annealing on charcoal blocks may cause firescale in Argentium Silver. The charcoal creates a reducing atmosphere that inhibits the formation of the protective germanium oxide surface layer during annealing or soldering.
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Casting
Q1. Castings have not completely filled - how can this problem be solved?
A. The pour temperature of the metal may have been too cold. The recommended pour temperature for Argentium 930 Silver is 930-950°C / 1706-1742°F.
A. The mould/flask temperature may have been too cold. The recommended mould temperature is 1005-1255°F / 540-680°C.
Q2. What can cause Argentium 930 Silver castings to be brittle?
A. The alloy may have been overheated. Use a pour temperature of 1706-1742°F/930-950°C. Argentium 930 Silver glows a paler red than standard sterling siver, when molten; it is therefore recommended to use accurate temperature control. If this is not available, it is best to work in a shaded area to clearly observe the colour difference of the metal at red heat.
A. Make sure that the melt has not been contaminated by silicon, as this can cause brittleness. It is best practice to use separate crucibles for Argentium Silver, to prevent cross-contamination.
A. The ductile properties of the silver will diminish if alloy is recycled too much. Higher percentages of fresh alloy will give more ductile castings. It is recommended to use at least 60% fresh alloy and more preferably 75% fresh alloy for recycling.
A. Quenching the flask too soon can cause brittleness. It is recommended to wait at least 15 minutes before quenching. Longer cooling times result in harder castings, for this reason, flasks can be air-cooled to room temperature before breaking out the casting. N.B. Larger castings will take longer to cool.
A. It is important to protect the melt if you are not casting in a vacuum/inert system, to minimise evaporation of the boron grain refiner in Argentium Silver. Boric acid, borax, charcoal, wood and graphite powder can be used for this purpose (most casters use boric acid).
A. Jerking or hiting the flask as it cools may cause castings to crack.
Q3. What can cause imperfections in Argentium Silver castings?
A. Silicon carbide crucibles can contaminate the melt and cause imperfections in the cast alloy. It is recommended to use clay graphite or pure graphite crucibles.
A. Investment powder residues from recycled material will cause contamination - it is important to thoroughly clean recycled material before use.
A. Use separate crucibles for Argentium Silver, to prevent cross-contamination with other alloys.
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Degreasing and rinsing
Q1. Why has Argentium Silver discoloured after a short period of time?
A. Discolouration can be caused through some degreasing agents, where:
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a film is left on the surface of the silver, which discolours with time
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the degreasing agent is not effective at removing deposits from the silver, which discolour with time
Q2. Can you recommend a degreasing agent for small workshops?
A. Dishwashing detergents can be recommended (e.g. Joy), diluted with tap water at approximately 0.5 : 100 and heated to approximately 122-130°F/50-54°C, used in an ultrasonic cleaning tank. Immerse for aproximately 1-2 minutes.
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Polishing and finishing
Q1. Will finishing process remove the germanium oxide protective surface?
A. The protective germanium oxide is able to replenish itself through the migration of germanium atoms to the surface; tarnish resistance can therefore be sustained, even when the surface is abraded or polished.
Q.2. Do I have to heat my Argentium Silver to activate tarnish resistance?
A. It is not vital to heat final pieces, as the protective germanium oxide surface layer develops naturally at room temperature, however, the benefit of applying heat to Argentium Silver alloys is that heat promotes the formation of the germanium oxide. A simple heat treatment is to bake in an oven or furnace at 250°F/120°C for 20 minutes.
Q3. Why do Argentium Silver articles benefit from a wipe with a silver cloth?
A. Some silver cloths are impregnated with thiols. Thiols are compounds that form a strong chemical bond with Argentium Silver (thiol bonding with standard sterling is much weaker) and help to give the surface extra protection from everyday pollutants, finger-marks and water-marks. Argentium thiol products currently being developed. Goddard's Longterm Silver Cloths and Tiffany & Co. polishing mitts are recommended.
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Other technical questions
Q. How can you distinguish between Argentium Silver and standard sterling?
A. Cynthia Eid recommends: "If you can't identify a piece of metal, first sand, scrap, or otherwise abrade the surface to make sure there isn't a fine-silver surface coating. Then heat the metal with a torch, being sure to take the flame off the metal occasionally to expose it to oxygen. If the metal is traditional sterling, it will turn black and stay black. If the metal is Argentium Sterling, it may turn black, but as you keep heating, the metal will turn white again. It can be helpful to test a known piece of each alloy at the same time."
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Health and Safety
Q1. Does Argentium Silver contain nickel?
A. No, Argentium Silver does not contain nickel.
Q2. Is Argentium Silver safe to use for articles that come into contact with food?
A. Yes, Argentium Silver is certified to the proposed European Standard pr EN ISO 8442-7 "Materials and Articles in Contact with Foodstuffs - Cutlery & Table Holloware - part 7" (see document below).
Certificate to Conformity to pr EN ISO 8442-7 by CATRA (pdf download)
Q3. How safe is the element germanium?
A. Please see safety data sheet below:
MSDS germanium by Teckcominco (pdf download)
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