Silver tolerances and solder

I have looked into the laws regarding silver tolerances around solder. It is a tolerance of 6 parts per thousand where solder is used and 2 where no solder is used. What exactly does this mean given silver solders are never plumb, most are around 60-70 percent silver which is around 400-300 parts per thousand non-silver metals. Does the tolerance mean the solder itself can only deviate by 6 parts per thousand or that the joint can only deviate by 6 parts per thousand? How would you know if you were safe or not?

Does this make fine silver with sterling as solder (which only deviates 75 parts per thousand compared to 400-300) safer than sterling and standard solder?

I am sort of confused and don’t want to break the law or sell something unethical so if someone could help me understand what these laws mean (or point me to someone who can) I would greatly appreciate it.

You may be overthinking the guidelines. a bit. It’s based on the
finished weight of the piece. So the amount of alloying metal
can’t exceed those tolerance for the whole item; not just the
minuscule amount of solder used in the finished item.

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MJSA put out an article from the USA ftc about metal purities and stamping of such. It came out July of 2018. Im sure if you wrote to them about your confusion they would have an answer. I for one never worried about this. If you find out something about solder making a huge impact on how we stamp our pieces, let us know. It just might turn out that it is something no one else ever thought about, and will cause a new spate of rulings.

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Oh I see.Sso if there is a piece without any solder in it the tolerance is 2 parts per thousand. If the piece has solder in it the tolerance is 6 parts per thousand.

I have done some calculations. Here I assume the solder for .999 is sterling and the solder for .925 is 65% silver. This is for something like a jump ring which seems to be most consequential. I also assumes the pallion was 0.02 grams, I weighed my pallions yesterday and most seemed to be around 0.013-0.016 grams.

0.3 gram .999

1 pallions, 0.02 grams solder

0.0015 grams non silver

Or 4.7 parts per thousand in the whole piece

Finished percent: 99.43%

0.3 gram .925

0.0225 grams copper

1 pallion. 0.02 gram solder

0.007 grams non silver

Total non silver: 0.0295

Finished percent: 90.68%

So with a tolerance of 0.6% percent the fine silver passes and the sterling doesn’t…,

Hi, also a Canadian! The law is based on the overall metal content with the understanding that solder must be used in fabrication. In order to solder, the solder must melt at a lower temperature, which therefore means that it is a lower grade. The standard of using 925 solder on 999 silver is a known, you are not creating the piece out of 925. It is a minor very minor portion of the product. Stamp it 999 you are not breaking the law.

You can buy plumb sterling solder from Stuller. I use it when soldering sterling.

I checked on stuller’s website and thier solders contain 80% silver for thier hard, 70% for medium and 60% for easy. No silver solder to my knowledge is plumb 92.5% silver.

In the US the tolerance is 10 parts per thousand which seems much more reasonable than 6. The silver tolerance is actually less than our tolerance for gold (7 parts but per thousand) even though gold solder is plumb and silver isn’t! Anyway, it seems that you would have to sparing with solder whether it’s .999 or .925 because not matter which you go with it seems to be a hallmarking landmine…