Two Questions About Solder Bar and Mixing with Pure Lead

[phantom22]

1: Is the tin/lead weight of the bar measured in mass or volume? The bars I have are 67/33 tin/lead and weigh 1 2/3lbs or approx. 26.66oz. Does that mean that the makeup of the bar is 17.86oz tin and 8.79oz lead or do I have to figure the volume and do the percentages from there.

2. To make a 16:1 lead/tin alloy does that mean 16lbs of lead and 1lb of tin for a total of 17lbs?

[kevin c]

1: By weight.

2: Its a ratio. 16:1 is 16 parts of one substance to 1 part of another. That’s for whatever unit of measure that’s applicable: weight, volume, length, etc.

[phantom22]

Thanks, I figured it was by weight. So 16lbs of lead and 1lb of tin will make my 16:1 alloy, is that right?

[kevin c]

Yes.

With your solder, that’s be a bit more than a pound and a half added to a bit less than 15 1/2 pounds of pure for a total of 17# of the final alloy. You can use the alloy calculators if you want to be more exact.

ETA: if you have bars of eutectic lead/tin solder, I believe they are 63% tin and 37% lead.


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[phantom22]

I have a bunch of kester bars that are stamped 67/33.

[kevin c]

Can’t argue with that ;^)


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[RogerDat]

I think that may be 67 Pb and 33 Sn which would be a common plumbing alloy. And as pointed out 63 Sn 37 Pb would be the eutectic alloy also somewhat common. No mention of a 67 Sn and 33 Pb alloy specifically in the table despite covering a lot of solder alloys. https://en.wikipedia.org/wiki/Solder_alloys

Look in the table toward the bottom of that article. You will find both the 67 Pb / 33 Sn and the 63 Sn / 37 Pb solders. With no 67 Sn / 33 Pb. If you have a good thermometer you might be able to narrow it down by melt temperature and temperature it plateaus at when cooling back to a solid.

Lot of difference between 33% tin and 67% tin for you calculation to make 20:1 alloy. If you are doing enough alloy or have enough solder it could be worth sending a small piece to member BNE for testing, cost you a pound of lead but if you want to know what you really have that will do it and leave no doubt.

[kevin c]

Isn't the convention that the tin percentage is the leading set of numbers, or did I just pull that out of the fuzz, navel lint and mothballs in my head that make me mix up memory and imagination?

[phantom22]

So I double checked my bars and they are indeed marked 63/37. My memory isn't what it used to be apparently.

[Land Owner]

Oh Goodie! Word Problems!!!

Use a similar calculation as your first post and recalculate for 63% Sn and 37% Pb on a 26.66 oz. bar (the sum of the parts equals the whole).

Keeping UNITS in ounces, multiply the Sn part above by 16, subtract from that the Pb part of the 37% bar to determine the OUNCES of Pb you need to add to the melt. Divide that by 16 (ounces per pound) to determine the weight of Pb in pounds.

I point out that EXACTITUDE is not the end game in making an alloy. Close to the pin is often quite acceptable.

[kevin c]

Consistency versus exactness? I'm fairly OC, and like to know exactly what I'm shooting, though what I've gained with age (experience and common sense, I'd like to think, but really, more impatience and an unwillingness to put in the effort) tells me I don't need all of the exactness for my application (coated pistol boolits shot at very short range and in volume).

Now I compromise and settle for consistent: large batches of casting alloy made of known component stock alloys. With each batch I'll be shooting consistent boolits from beginning to end. Oh, I'll try to mix each batch "exactly", but now it'll be to the nearest 10# ingot added to the 240# batch in the processing pot, not to the nearest ounce.

[Drm50]

I'm 69 and have poured bullets since I was a kid. The guys who taught me weren't technical on alloy but they knew what they were doing. Boolits were pistol or LV rifle like 25/20-45/70 ect. They went for uniform mixes that were primarily Lead- WWs & Tin. I go about it the same way because I don't shoot anything that requires technical alloy. I work up metal just as I would powder load for individual guns. On my target WCs I back them down soft as possible. The others I just go by standards in casting manuals for alloys. The only leading problem I've ever had was with 45Colt Speer lead bullets shot at 750fps/ Unique. I never bought Speer lead bullets before or since.

[phantom22]

Had my first casting session with the alloy and made some very nice .40 bullets. Over 600 of them! They all filled out nicely. It was a 175gn mold that seemed to drop them at an average of 177gn. Now to powder coat them and give them a go.

[kevin c]

You're on your way!

FYI, many here would likely save the expensive tin by limiting it to one or two percent for improved fill out, and get the hardness they want by adding less pricey antimony for air cooled casting, and even more hardness water dropped or heat treated (which takes a bit of arsenic, I believe).

[Ohio Rusty]

I have some bars that say either 50/50 or HALF AND HALF. (National Lead company hallmark on some.) I'm assuming those bars are 50% lead and 50% tin ??
I found on the Otley plumbing site they are indeed 50 lead 50 tin.
Ohio Rusty ><>

[alamogunr]

I just went to the chart referenced by RogerDat. I'm not sure that any convention of referencing solder alloys is consistent. The Wikipedia chart has so many alloys listed that there could be a consistent order of components but I didn't take the time to try to determine what it was.

I have a large supply of wire solder in original boxes that specifies the contents as 40/60, or 40% Sn and 60% Pb. Apparently, this is not as common as 60/40 because I have been "corrected" several times when I have mentioned it.

I agree with RogerDat that the OP should send a sample to someone who can verify the alloy. Tin is valuable enough that you don't want to waste it by using too much. It would also put to rest the identification as either 67/33 or 33/67. I'm in the group that guesses it is 67/33. Don't get too hung up on exact percentages. The analysis will probably have decimals on each number.

I enjoy using alloy calculators which have been posted on this site but if I come within 4 or 5 percent of a target alloy, I am satisfied.

[uscra112]

A hardness tester for lead might be a good acquisition, if a bit spendy. I have a Cabine Tree which is handy for testing ingots, and a SAECO for testing bullets. A while ago I made a "slug mould" which casts a flat-ended cylindrical "bullet" for easier handling in the SAECO tester.

[RogerDat]

I think at some point the convention of lead/tin was replaced with tin/lead. I recall in my youth 70/30 solder was common and that was 30 tin. But when I look at more some solder bars it isn't uncommon to see the tin percentage listed first. I have some bars that are marked 30-70 and 40\60 but have heard that same 40\60 referred to as 60 40 solder.

Lord knows it would make marking our own alloys and ingots from scrap that have been tested a lot easier if I didn't have to include the Sn and Sb designation but since one can't count on any convention or even ones memory sometimes it requires a bit more marking to make sure I know what I have.