20/1

[weasel 21]

Looking for the formula for 20/1 & 30/1 alloy mix. I want to mix my own.

[ktw]

20 or 30 parts pure lead to one part pure tin (by weight).

[weasel 21]

OK, I think that means 20 pounds pure lead mixed with 1 pound tin would equal 21 pounds of 20/1 alloy.

[JeffinNZ]

And if you are using 50-50 lead/tin solder for the source of tin the ratio becomes 19 parts lead and 2 part solder.

[weasel 21]

I have a bar that says "Gardiner Solder" there are no other markings on it. About 1"x12", is it tin? On the back of the bar SN 68-PURE ALLOY.

[calaloo]

SN is the chemical symbol for tin. It is probably 68% tin.

Bill

[runfiverun]

weigh that bar figure for 70% of the weight and add the proper amount for your mix.

[Tom Myers]

I have a bar that says "Gardiner Solder" there are no other markings on it. About 1"x12", is it tin? On the back of the bar SN 68-PURE ALLOY.

Weasel,

Your bar of Gardiner solder is an alloy of 68% tin and 32% lead.

You want to add enough solder to 10 lb of pure lead to form an alloy that equals 20 lb of lead and 1 lb of tin which would consist of

1/21 or 4.76% tin and 95.24% lead.

So:

( 0.68*X ) equals the pounds of solder to add.

( 10 + X ) equals the weight, in pounds, of the 20:1 alloy.

Then:

0.68*X / ( 10 + 0.32*X ) = 0.0476
0.68*X = 0.0476 * ( 10 + 0.32*X )
0.68*X = .4762 + 0.0152*X
0.68*X - 0.0152*X = .4762
0.6648*X = 0.4762
X = 0.4762 / 0.6648
X = 0.7163

Add 0.7163 pounds of Gardiner solder to 10 pounds of pure lead to achieve a 20:1 Lead:Tin alloy

Or, if the bar of Gardiner solder weights exactly one pound, you could just add 13.28 pounds of pure lead to your one pound bar of solder to acheive the 20:1 alloy

0.68 lb of Tin / (1 / 21 ) = Total weight
0.68 / 0.047619047 = 14.28 lb
14.28 - 1 lb of solder = 13.28 lb of pure lead

Or, if the bar does not weigh exactly 1 pound, weigh it and then divide that weight by 0.0753 to determine the weight of pure lead to add the solder to.

*****************

A 30:1 alloy would consist of 1/31 = 0.0322

Then

0.68*X / ( 10 + 0.32*X ) = 0.0323
0.68*X = 0.0323 * ( 10 + 0.32*X )
0.68*X = 0.3226 + 0.0103*X
0.68*X - 0.0103*X = 0.3226
0.6697*X = 0.3226
X = 0.3226 / 0.6697
X = 0.4817

Add 0.4817 pounds of Gardiner solder to 10 pounds of pure lead to achieve a 30:1 Lead:Tin alloy.

Or, if the bar of Gardiner solder weights exactly one pound, you could just add 20.08 pounds of pure lead to your one pound bar of solder to acheive the 30:1 alloy

0.68 lb of Tin / (1 / 31 ) = Total weight
0.68 / 0.032258064 = 21.08 lb
21.08 - 1 lb of solder = 20.08 lb of pure lead

Or, if the bar does not weigh exactly 1 pound, weigh it and then divide that weight by 0.0498 to determine the weight of pure lead to add the solder to.


Hope this helps.

Tom Myers
Precision Ballistics and Records (http://www.tmtpages.com)