Question on lead / tin percentages

[kenk]

Afternoon, I asked this question on another forum, but though I would run it by you guys as well. I have the attached laying around, and am unsure if they would be of any value for casting, as the tin content is likely to high. They are used in the printed circuit board industry, and are 60% tin, and 40% lead, measuring aprx 1.5” in diameter.
Any thoughts on if these could be utilized for casting?
Thanks

https://i.postimg.cc/8CQw54mJ/47-F4-E384-FBD9-4036-B3-C5-CDB83090-C5-C3.jpg

[NyFirefighter357]

Short answer yes
60/40 solder
1%-2% tin for better fill out.

What do they weigh?

1lb of 60/40 solder mixed with 39/40lb lead would give you 1.5% tin.

[Winger Ed.]

I'd use them to mix into my alloy if I had them instead of pure Tin or 95/5 solder.

They're too valuable to use straight.

[kenk]

Short answer yes
60/40 solder
1%-2% tin for better fill out.

What do they weigh?

1lb of 60/40 solder mixed with 39/40lb lead would give you 1.5% tin.

Thanks. Not sure what they weigh but I wouldn’t want to get hit by one


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[kenk]

Short answer yes
60/40 solder
1%-2% tin for better fill out.

What do they weigh?

1lb of 60/40 solder mixed with 39/40lb lead would give you 1.5% tin.

So I could actually use them then as is, is that correct?
Thanks so much!


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[Land Owner]

We are saying, "yes, you can use them", but less concentrated from their current 60% tin. Dilute them, by weight, into a lead-tin alloy of 1.5% to 2% tin.

Tin is the "expensive part" of alloying, at about 10 times the cost of lead. It does not take much tin for the alloy to conform to a hot mold. Lead, by itself, is not as "greasy" as an alloy of lead and tin. Tin, at ~2%, by weight, helps solve the headache of incomplete mold "fill out", which is widely recognized.

[GregLaROCHE]

I don’t see any problems using them pure, but it’s a shame to waste all the tin in them, when you could be adding it to a mix that needs a bit of tin.

[kenk]

Thanks, I have reloaded for years, but am just getting started at casting, and know next to nothing about it. Would I just add more lead into the pot with one of these solder balls to increase the lead content? Also, if I used the solder balls by them selves, it would work ok to it sounds like, correct? I have a bunch of old egg sinkers I could Add for starters, but haven’t found a reasonably priced lead source yet.
Thanks for the help on this, I believe I’m going to enjoy casting a lot

Ken

[kevin c]

As commented on above, tin is expensive, so using no more than the small amount needed to make lead cast well is what most recommend.

At 60% tin, one part by weight of your solder balls melted into 59 of non tin containing alloy gives you 1% tin content, which is often enough to cast well. Similarly, one part to 29 yields the 2% content that is the most needed for ease of casting, though more is used by those looking for other effects on their alloy.

My personal take is that good reliable alloy with consistent content helps the new caster through the learning curve, so I agree that commercial alloy with a guarantee on content while expensive, is worthwhile (remember you can always remelt any mistakes); mixing your own means more things that could go wrong while learning the ropes.

As for adding the solder and lead into the casting pot as you go, it’ll work if you always add the same ratio of each to the already mixed alloy in the pot. Otherwise the content may vary with each addition. Not a concern for some applications, but important for those seeking the greatest consistency.

[Land Owner]

Weigh them! And it will take some SIMPLE MATH on your part to develop a formula for adding Tin and Lead to make an effective alloy.

Here is the SIMPLE MATH (substitute the WEIGHT of EACH sample into these equations):

Total weight of Tin in a sample:
Multiply the weight of the 60/40 sample TIMES 0.60
Sample Wt. * 0.60 ==> [Equation A]

Choose the weight of Tin you want in a Lead-Tin ALLOY ==> say 2%

How much Lead-Tin alloy, at 2% Tin, can be made from one (1) 60/40 sample?
[Equation A] DIVIDED by 0.02 ==> [Equation B]

ADD the weight of Equation B, as Lead, into the melting pot.
ADD the weighed 60/40 sample into the melting pot.
[Equation B] + 60/40 sample ==> [Equation C]

When [Equation C] is fluxed and melted, the resulting alloy will be nearly 2% Tin.

++++++++++++++++++++++++++++++++++++++++++++++++++ +

Test these equations:

SAY the 60/40 sample weighs exactly 1-pound (16 ounces).

[Equation A] equals 9.6 ounces of TIN in the 1-pound 60/40 sample.

[Equation B] equals 480 total ounces of ALLOY at 2% Tin from the 1-pound sample.

There are already (16 minus 9.6 =) 6.4 ounces of Lead in the 60/40 sample.

So, 480 ounces MINUS 6.4 ounces = 473.6 ounces (29.6 pounds) of ADDITIONAL Lead is required (that's a LOT of sinkers).

[243winxb]

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