What can I do with pure tin

[chutestrate]

I lucked into a couple of pounds of pure tin. How should I use it? Should I mix it with some of the lead I have, and then use that batch to harden up softer lead in the future?

[fryboy]

use it sparingly !!!! and only when needed to get proper fill out of a mold ,tin of it's self doesnt harden lead too much ,2 pounds will sweeten 100 #'s of ww's ( 2% )

[chutestrate]

Thanks, but now that raises another noob question.

Is it only antimony that hardens?

How do I know when to use it? Do I get some crappy looking castings?

[lwknight]

Don't waste it. Tin will cost you about $12.00 or more per pound when you need some.

[303Guy]

I've had luck making an alloy from scrap lead pipe, lead sheeting and a small amount of tin. It casts real well and is reasonably tough. It sure expands well on impact and holds together well.

http://i388.photobucket.com/albums/oo327/303Guy/20gr2205_146PP.jpg Over 80% weight retention!

[lwknight]

Even a .5 percent of tin will make lead go from a 5 to 8 and after that it don't pay off so good.
Added tin is mostly to make better casts but it does strengthen the boolits a lot.
Strengthen and harden are not the same thing.
That equates to weght retention without losing expansion.
Antimony is where you get the hardness from and if you have muck antimony at all you will need 2% or so tin to keep the antimony from floating up and drossing out.

[chutestrate]

Ok, I still don't understand howI'm going to use this tin then. How will I know when I am casting to add a little lead to the mix?

[trk]

I've tried casting tin bullets. They come out AS HARD AS JACKETED. (42-43 on Rockwell B).
Best cast in a COLD mould.
They cool VERY slowly, so when the mould is hot you have to wait a lot.

[Edubya]

You could just send that nasty stuff to me! I'll pay the shipping and handling:)

Just add 2 oz. for each 10 lbs of WW and enjoy your results! Wheel weights do have a small amount of tin in them but it won't hurt to add this percent and your bullets will stay together even when they hit bone. I promise you that eventually you'll be grateful for learning this and for having the tin.

EW

[sagacious]

I've tried casting tin bullets. They come out AS HARD AS JACKETED. (42-43 on Rockwell B).
Best cast in a COLD mould.
They cool VERY slowly, so when the mould is hot you have to wait a lot.
You may have gotten some tin babbitt metal, or similar. Pure tin is dead soft and barely harder than pure lead, but babbitt is as hard as differential calculus.

[cbrick]

I've tried casting tin bullets. They come out AS HARD AS JACKETED. (42-43 on Rockwell B).

Pure tin is right at 7 BHN, pure lead 5 BHN.

The maximum hardness of a Sn/Pb alloy (63% Sn/37% Pb or 60/40 solder) is 17 BHN.

Sag could well be right about the babbit but whatever it was it wasn't just tin or a tin/lead alloy.

Rick

[lwknight]

Sagacious, the 99.9 tin bars I got from rotometals are pretty hard.
Also the little ingots that I made from then are way too hard to fingernail dent.

OK I just took one of my hardball RN boolits and crushed the nose into a tin ingot to make a pretty good dent and the nose was not affected. So you are right in that tin is not very hard.
It is a lot harder than soft lead though.

[cbrick]

lwknight, did you read post #11?

Rick

[lwknight]

Yea , I read it. Is a 7 a lot harder than a 5?
If that be the case then why the heck does anyone want boolits to be 18 or 20 hardness.
That would be like 100 times harder than lead.

I still had to bear down on the channel locks to dent the tin and I can dent lead easily , so it is a big difference.

[303Guy]

Strength versus hardness? Surface impurities making just the skin harder?

[cbrick]

Is a 7 a lot harder than a 5?

No, it is very slightly harder.


If that be the case then why the heck does anyone want boolits to be 18 or 20 hardness.
That would be like 100 times harder than lead.

No, it wouldn't. Not even close.

Rick

[sagacious]

Pure tin is very soft. BHN 7 is about right. But my 3rd grade teacher Miss Stevens would have said, "You're both right." OK... how so?

Pure tin ingots have a crystalline composition. Those crystals don't like being forcibly deformed, and are what produces the audible noise called 'tin cry' when the tin is bent. The crystal boundaries (crystal edges) work to reduce deformation as they resist it-- or as you push your fingernail into it. But the tin itself is very soft.

If you cold work the tin by rolling or extrusion, you crush the crystal structure, and the actual "hardness" of tin is easier to measure. This is different than lead, where 100% pure cast lead is very soft, and not made much 'softer' by cold working. That's why there's no 'lead cry' when you bend a cast bar of lead.

I was once given a quantity of 99.99% pure tin from a chem lab. It was in the form of 0.75" thich sheet. It was dead-soft. Not just bendy, but soft like pure lead sheet.

[lwknight]

So its not like the rictor scale?
What is double hardness of 5? And 7?

I know the scale is not linear and I know the math to test the hardness but what does it really mean in human terms

Does it bear any resemblance to the DB scale?

On the decibel scale, the smallest audible sound (near total silence) is 0 dB. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful than near total silence is 20 dB. A sound 1,000 times more powerful than near total silence is 30 dB

[semtav]

Ok, I still don't understand howI'm going to use this tin then. How will I know when I am casting to add a little lead to the mix?

Don't do anything with it. Put it in a safe place and go back to casting with what you've got.

You don't say what kind of bullet casting you do. ( Hunting, pistol, military, BPCR etc)

One day you will know what to do with it. Until then, just stash it.

[DukeInFlorida]

Here's how to handle your tin, if I can suggest a way. My plan for converting some linotype bars (pigs) caused the same concern. How to use "just a little" when I needed to.

My solution was to melt the large chunk of metal in a melting pot. And, then I ladled small one and two ounce amounts into my cupcake molds. When those cooled, I had round thin wafer type ingots, which I measured the weight of with a scale. I wrote the weights on each piece with a magic marker.

Now, when I need two ounces for alloying, I can find one of the wafers (or some combination of a couple or three of them), and use that, stirring it into the mix.

Treating your chunk of tin the same way would give you a similar result.

Check with the alloy charts to see how much (by weight) tin you need to add in order to effect a given alloy.

[lylejb]

Ok, I still don't understand howI'm going to use this tin then. How will I know when I am casting to add a little lead to the mix?


Tin is used to help correct poor mould fillout. If your boolits are having rounded off corners / bands / edges, and your reasonably sure the rest of your process is correct ( mould up to temperature, melt up to temperature, no contamination it the melt or mold ) then try adding 1-2% tin. It should help.

While some alloy has higher amounts of tin ( lyman #2 is 90 lead, 5 tin, 5 antimony) more than 2% tin doesn't gain as much. It's the point of diminishing returns. Many think using more than 2% tin is wasteful, as tin is about $12 / lb if you have to buy it new.

Tin does harden lead, but only a little bit. Tin adds toughness to the boolit, making less likely fragment on impact.

Antimony hardens lead much more effectivly than tin. This is why wheel weights are popular for casting, clip on wheel weights contain antimony in the alloy. While there's some speculation that WW's don't contain as much antimony as they used to, it's still a good source of inexpensive base alloy.

[Echo]

I like the idea of rendering your Sn down into manageable 2 oz. chunks. Allows easy managing of alloys - unless you were to use them with your turkey fryer, in which case a pound of Sn and 50 pounds of WW's would be viable. So.

Take them and melt in your furnace and dribble into 2 oz. mini-ingots. Use as needed. Two percent, or even less, to reduce the surface tension of the melt to produce shaarp corners where they should be.

Good idea, Duke. That is what I am going to do with some Sn I just got.

[deerslayer]

What form is the tin in now? If it is solder a measuring stick and a scale will net you the amount you need. In other forms Duke has a great idea.

[chutestrate]

Thanks Duke. That makes a lot of sense.

[fredj338]

Ok, I still don't understand howI'm going to use this tin then. How will I know when I am casting to add a little lead to the mix?

If you are using pure lead, a mix of 25-1 makes a good alloy for LHP, more ductile than ww/lead mixes. At 20-1, it works well for vel to 1200fps or so. If your alloy is ww, you really don;t need to add any tin, but 1% (3oz to 19#) may help mold fill out.

[Alex]

I like Ed's idea. Just send it to me and I'll figure out what to do with it. :wink: