Hi everyone, I’m a new member here and was looking for some advice.
I make jewelry, mostly working in silver, but I was wanting to get into making some objects that are food related - serving spoons, scoops, maybe vessels for water or teapots.
However my supplier of metals has told me that silver solder is not food safe, and so this has stumped me a little. Are there special food-safe solders I should be looking out for? They mentioned that theirs had a zinc content.
So I was just wondering what are other people using when they need to solder areas in their flatware and other objects? Any advice would be much appreciated!
I’ve never heard that before, but that doesn’t mean it’s not true. Let me ask around and see what some of my friends who make silverware and hollowware say. As far as I know, all jewelry grade silver solders have a little bit of zinc.
Maybe someone else in the forum knows? Let’s see if what others say as well.
So far as I know and from what I can find on the web, modern silver solders no longer contain lead or cadmium. Zinc is the primary additive along with copper to make silver solders. Zinc and copper are both essential trace elements for health. In excess, zinc (eg. zinc supplements taken in high dose and chronically) will cause a copper deficiency. Excess copper exposure will cause a zinc deficiency, as the same metal tranport mechanism in the gut wall cells, take in trace amounts of both elements. Over exposure to one element leads to a deficiency in the other, as both metals compete for the same binding site. The amount of zinc and copper contained in solder that will leach out, even in acid contain foods is neglible. Only storing acids like vinegar in a container made of sterling with soldered joints for long periods of time can leach out any significant amount of copper or zinc. I have seen only 1 case of copper deficiency leading to spinal cord and nerve damage in 40 years of specialty medical practice… the patient had been taking large (4X recommended) doses of zinc supplements on a daily basis for many years… To make a long story short, no- modern solders are safe. Lead and cadium free!
Hello
Use the hard silver solder which has the least amount of zinc @ 2-3% if you are concerned, a lot of Sterling silver flatware has solder on them.
Thanks
Ken
Jeff, talk to the people at the Metals Museum in Memphis TN. I use to go there 30 years ago and help with their restoration days. Those days were when people would bring in their antique items and have them repaired. Many items were food utensils and pots. They would be the best resource since they have to deal with it.
this is so interesting,thank you for all the detail! so it sounds like my supplier is sort of technically correct, but not so much in the application. This is really great to know!
silver and copper toxicity (sterling) is not a signficant problem. Your can go to OSHA and NIOSH websites to look it up… the below are google AI overviews of this subject… most of the references are from above.
Low toxicity**: Silver is not known to cause cancer, reproductive or neurological damage, or other chronic adverse effects.
Skin reactions**: Sterling silver can irritate the skin of people with sensitive skin.
Argyria**: Prolonged exposure to high levels of silver can cause argyria, a permanent blue-gray discoloration of the skin and other body tissues.
Exposure
Inhaling silver
Inhaling silver fumes or dust can irritate mucous membranes or the upper respiratory tract.
Drinking water
The EPA recommends that drinking water contain no more than 0.10 milligrams of silver per liter.
Workplace airThe Occupational Safety and Health Administration (OSHA) limits silver in workplace air to 0.01 milligrams per cubic meter.
Jewelry
Hypoallergenic metalsSterling silver is hypoallergenic and less likely to cause allergic reactions. Flashing and plating**
Some manufacturers apply a thin layer of pure silver or another metal to reduce irritation.
Rhodium coating**Some sterling silver jewelry is coated with rhodium to make it more resistant to tarnishing.
SILVER SOLDER
Silver solder can be toxic to humans if swallowed or inhaled in large amounts. Symptoms include skin discoloration, respiratory irritation, and nervous system issues.
Symptoms
Skin**: Argyria, an irreversible bluish-gray or ash gray discoloration of the skin
Eyes**: Argyrosis, an irreversible bluish-gray or ash gray discoloration of the eyes
Respiratory**: Coughing, difficulty breathing, or respiratory irritation
Nervous system**: Confusion, hallucinations, headache, seizures, or coma
Muscles and joints**: Muscle aches, weakness, joint pain, or paralysis
Other**: Low blood pressure, fatigue, tremor, twitching, or uncoordinated movements.
Before you scare yourself, argyria, due to silver toxicity itself, is the predominant cause of symptoms… this condition is so rare that it’s no longer talked about. People who deliberately ingest silver salts will get sick from silver itself… solder related copper and zinc toxicity is also almost non existent. Toxic cases are almost always related to industrial exposure…or acute ingestion…symptoms of ingestion are mostly gastrointestinal: copper sulfate and zinc salts are highly irritating to the stomach…Neurologic symptoms are usually chronic toxicity…the habitual use of solid copper cookware for preparing and storing acidic foods is one cause but also exceedly rare… IN SHORT: occassional use of flat ware is NOT going to be dangerous.
To follow through. Everyone that I contacted who makes silverware and hollowware professionally said that they’ve never heard that jewelry grade silver solder is a problem.
I’ve never heard of this either.
Hope all of the answers from everyone help you sort this out!
I once wrote about metal toxicity, your response was similar… the incidence of agyria is vanishingly small… I can’t find any reference saying that modern lead and cadmium free solders present a health problem.
No problem, you’re most welcome!.. I never heard of nor can find any references that the use of modern lead and cadmium free solders present a health risk… vessels of copper storing acids like vinegar for long periods of time are more of a risk… the EPA and OSHA limits on silver metal are very low… these standards are fixed by industrial exposure processes where workers are not using protective equipment… mining and smelting of silver ores do present risks as heavy metal contaminants, particularly lead, cadium, arsenic, and other toxic heavy metals are present and volatilized by high temperature… Modern silver and copper mining in the US has to follow very strict standards… Mining companies have liability concerns for worker exposure. These concerns do not apply to using flatware… nor present a hazard for home studios so long as an exhaust vent over soldering and melting work is used…making flatware generates fumes, using them generates nothing…