A simple test or something?
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A simple test or something?
Hi, If You have a bar of tin, thin enough that You can bend it with Your hands, keep it right next to Your ear and bend it in silent environment; If it's pure or near pure tin it says "rtin...rtin...rtin" or creaks or what ever is the correct expression for it anyway... If it's weaker alloy like 60/40 or 40/60 or 38/67 or something else it won't make any sound.
Hi, guys: Besides making the groaning noise when bent like Finn45 said, tin reacts with hot concentrated lye water to make bubbles and a white insoluble residue. Lead doesn't do that. If you make some lye water for a test, only make a small amount and wear eye protection. Lye gets hot and will explode when water comes in contact with it, so when mixing a solution be very careful! Also, tin never tarnishes and is always bright silver colored and shiny, while lead is dark and grayish colored except when first cut, but it turns gray in a few days. Lead is soft enough to be dented with your fingernail but tin is not. Unfortunately, when you find these metals they are usually alloyed, which covers up all of these identifying properties. Zinc also makes a crackling noise when bent, but it sounds different, more like breaking toothpicks. Zinc is a dark bluish-silver colored metal and is never shiny except when freshly cut.
To determine the approximate amounts of these metals in lead-tin alloys is pretty simple with a reloading scale. All you need to do is weigh a small piece then weigh the same piece under water and find its specific gravity by dividing the dry weight by the difference of the dry and wet weights. Lead has a specific gravity of 11.34 and tin has a specific gravity of 7.31, and using the following method the percentages of each in the alloy can be determined. Using the formula of:
x/spec grav lead + (1-x)/spec grav tin = 1/ spec grav of alloy. To find the percentages of lead and tin solve for x. Let's say that the specific gravity of the lead-tin alloy is 9.15. Then x/11.34 + (1-x)/7.31 = 1/9.15 Turning the math crank we now get 0.0882x + 0.1368 - 0.1368x = 0.1093. Combining like terms we end up with
-0.0486x = -0.0275, then solving for x we have x = -0.0275/-0.0486 or x = 0.5658, which translates to 56.58% lead and 43.42% tin. We know that the lead is 56.58% and not 43.42% because the lead specific gravity was used as the first value in the sequence of operations in the formula. Because of that, make sure to get the sequence of operations right so that the correct value gets assigned to the correct metal. I hope I didn’t make any typos, I looked it over, and it seems okay. For those of you with an electronics background you'll notice that the formula is the same one that is used for finding resistance values for resistors in parallel!
Hi,Linstrum.
Thanks for the post.Very interesting.How do you measure underwater with your reloading scale?Do you have your pan dunked in a cup or something?
I'd like to give this a try.
Art Croft
Hi, Art: To find specific gravity, I place my reloading scale so the pan is hanging over the edge of the work bench and then I check and re-zero it with the pan in place, the same as it is always used. The zero should be checked because the scale was moved to a new location. To find the dry and submerged weights of the test metal, I suspend the test sample by a length of very light weight sewing thread, with one end tied onto the scale pan support on the other end glued onto the metal with just enough instant setting crazy glue to make it stick and hold its weight. If the piece of metal to be tested is very large, say around 200-300 grains, then you could just tie the thread around the piece of alloy, but the less thread that is under water, the better. I weigh it dry first, then use a clean clear glass or plastic container like a cup, drinking glass, etc., to hold some cold water and weigh it under water by bringing up the cup from below until the piece is totally submerged with maybe an inch of water over the top to make sure it is all the way under water. I take a soda straw and tease the air bubbles off of the metal and thread so they don’t buoy it up and change the reading any. I do the underwater weighing several times until the same weight reading is achieved consistently.
Don’t worry about the weight of the sewing thread changing the readings. In relationship to the weight of the piece of test metal, the thread is so light that its influence on the test results are inconsequential, especially if the test metal is pretty heavy. Make sure that the thread is long enough to tie the metal onto the scale and then hang the metal down far enough to let go into the glass cup. Use glass so you can see what is going on underwater. I do specific gravity tests all the time. I recently used it to determine the kind of metal alloy I got at the recycling yard when I found a bar of metal in with the stainless steel that was far too heavy to be stainless steel. Stainless runs around 8 times as heavy as water and the stuff I found was about 19 times as heavy as water. The bar of metal I paid a buck for turned out to be a bar of tungsten worth $400!
Regards,
I found a block of metal I couldn't identify,so thought I'd try what I learned here. Weighed it underwater and now my camera doesn't work.
Thanks again,Linstrum.
I enjoy the BPCR ,and the busiest site for us since shooters.com fizzeled is on groups.msn.com/BPCR.
Can I post a link on that site to here in reference to your post?
Art Croft
No problem with links here ! Both ways is nice though,,if you dont mind. ;-)
Tin is a chemical element. That means that it will change from a liquid to a solid at one (and only one) temperature. Thus if you have enough of this stuff you can heat it up and track its temperature as it cools. Technique is important here (and I can discuss that if you are interested), but you could identify pure tin.
I posted the page at said site.Here it is..I hope.
http://groups.msn.com/BPCR/general.m...24998330929974
Hmm,didn't light up ...I'll find a way to let you enjoy the replies from the other site.If anyone looks...there are a good amount of casters in BPCR.
Art Croft
Hi,
I thought I'd mention something here. I'm always looking for scrape Tin myself. What you don't want is any Zinc!!! And this looks like Tin and there's plenty of it around so be careful. One way to test for Tin is it has a certain melting point I don't have the scale in in front of me but zinc is several hudred degrees off of this,so what you can do is get a Tempil stick crayon in the tins melting point and heat with a small propane torch and if the metal melts when the crayon melts you've got Tin!
Most srape dealers would not know Tin if a ton fell on them, so I try to figure this out myself and you can carry the torch and crayon to the scrape yard and test for it there. Just my thoughts!
Well, here is my 2 cents - when I bought some from a large scrap metal supplier they used Silver Nitrate (I believe) and when dripped on to the Tin it turned a blue color.
They did say it was expensive stuff, but I have never bothered to look for it. In small quanitities it might not break the bank.
5Shot