"Dimples" in your ingots

[Chris24]

I've noticed something when I cast ingots, and I'm sure others have too. The purer the lead, the more they sag in the middle. It makes sense, since tin helps fill out molds. Pure lead is shiny, but smooth. The more antimony and tin, the more crystalline the ingot is. I've found a couple posts referring to this, but not much.

I smelted clip-on weights, and the ingots were almost flat in the middle. I then smelted stick-on, and there were big "thumbprints" in the middle. I also smelted a mix of both, and the dimple was there, but much smaller. It's easy to keep mine sorted that way.

[RogerDat]

Labeling works too. ;-)

Contraction of cooling metal after partial solidification causes depression. Temperature of melt and size/shape of mold make a difference in how pronounced this effect is.

The stuff you mention can be an indicator on the other hand I have bread loaf slab ingots that show a metal flake or fine grained surface and both gun as 99.5 Pb with .5 tin so only 1/2 of 1% tin in both and they look different. Think how fast they cooled determined did they form larger crystals that look like flakes or small grainy crystals on the surface.

[Chris24]

I don't label them, but I do keep them separated. I understand about cooling speed, though. I poured the ingots all at the same time in the same molds, so they cooled at the same rate. That makes it more reliable. I wouldn't trust it on just random ingots.

[bangerjim]

Who cares what ingots look like! As long as you have fluxed good (3X) when making them you are good to go.

Marking them is almost an necessity when you start gettin thousands of them like me!!!!! And over 12 different alloys!!!! I use a 2 letter code with HF metal stamps. Hold them together and one whack of a hammer and they are marked permanently. I also spray the ends with colored wood lacquer so I can EASILY ID them when stacked on the shelves.

But do what you feel works for you. Marking them permanently makes them more valuable when selling or trading......when you are gone! "Life is short.......and suddenly you aren't there anymore."

bangerjim

[Chris24]

They're fluxed at least 3 or 4 times. I even skim the ingots after I pour them.

I'm just starting out. When I get up into the hundreds of pounds, I will definitely mark them. I haven't even finished my final boolit alloys yet.

[JSnover]

Interesting but I don't know if I would call it a reliable indicator. A set of El Cheapo metal stamps (or a box of Sharpies) will save you some head-scratching down the road.

[RogerDat]

How it melts, how it casts, how it fills the ingot mold can certainly tell you something about the alloy in the case of ingots of unknown alloy. Noticing the difference in how the lead "dimples" in the ingots is observant, sharing that observation is useful. So all good.

The trusty sharpie marker can save you some hassle later. Just a quick "WW" or "PB" for COWW's or plain, maybe SOWW for the stickons. Mixed you can do WW-PB or whatever works for you. Only difference between your lead stash and BangerJim's is you are still working on your first 1000 lbs. and Jim there is working on his.... well not his first anyway (probably not his second or third 1000# either)

I would suggest mixing your bullet alloy in smallish batches at first at least until you know how an alloy works in your mold and shoots out of your firearm. Keeping your ingredients in separate ingots until being used for bullet casting. You can combine the different alloys lots of ways, taking them back apart after they have been melted together not really an option. Good to have COWW's separate from plain separate from any tin or printers lead until mixing for bullet casting.

I box my ingots and label the box but I still label each ingot going into the box. Really helps when I have a box or two open and I'm pulling ingots out to mix into a bullet casting alloy. Nice to know exactly what I have stacked on the table even after it is out of the box.

I don't know what you are using for a mold, I use steel angle iron that makes three 8 inch ingots and the first fill will cool a lot faster than the third fill. The mold heats up. I'm using three in rotation and by the third or fourth filling they are all hot enough to seem hot through welding gloves. I can tell the difference in the ingots from the first fillings and after the mold gets hot. Those slabs I mentioned are like 15 lbs. poured into a bread loaf pan, totally for bulk storage of raw materials or big batch of mystery metal. I'll get a representative slab gunned and know what the whole batch of slabs are.

[Beagle333]

+1 for Sharpies. I have some ingots that have been piled out in the sun and rain for months now and the letters are still very readable, even though the ingots are kinda turning white. (I gotta remember to use those up!):oops:

[Chris24]

I'm just using some cheap muffin pans from the thrift store. They make a standard size that's easy to stack. That's why the dimples are so apparent. The round shape sags more in the middle than a thin bar. I'll have to find a Sharpie tomorrow, so I can mark them.

[RogerDat]

I'm just using some cheap muffin pans from the thrift store. They make a standard size that's easy to stack. That's why the dimples are so apparent. The round shape sags more in the middle than a thin bar. I'll have to find a Sharpie tomorrow, so I can mark them.

You are right the muffin ingots do show the dimple more than most. I still use those muffing tins fairly often. If nothing else I pour 1/4 inch thick "coins" with scrap solder using them. Allows me to deal with any acid core flux or oxidation in an old pot just for "crud" melting. I sometimes I find old solder which has lost it labeling. Melt one big batch with several months worth of garage sale or scrap yard solder purchases into coins, get a few coins from the batch gunned at scrap yard, label and store together. Have a bunch of these coins now with "30 Sn" or "43 Sn" or whatever written on them. Like coffee cans of coins I have collected over the last couple of years.

I like the muffin tins and don't plan to re-melt the bucket of ingots I already have, muffing tins are about the least expensive way to get a lot of molds that make good ingots. I just had the angle iron, access to a welder and 8 inch bars made from them fit inside a USPS flat rate small or medium box just right. The pack at around 20# per box. Easy for me to move and stack. Ready to ship if I get hit by a bus and the kids need to sell them. Or if I need to sell them, one never knows. I will say always test with just one ingot before filling all the cups, some muffin tins the lead will stick to. Much better to find this out with one ingot than when you have to bang and peel the muffin pan off of a dozen of them. Don't ask how I know this is a PITA.

Now that I have some other molds I still use the muffin tins for "odd" scrap, stuff that has some alloy that is not typical stuff like WW's or plain or solder. When I find something like dental x-ray foil that is like an improved COWW alloy, or some stuff that is 4% tin. Know just by looking at the ingot that it is not the normal lead supply because it is a muffin. Just a little can stack on a shelf, or if more can put in a bucket or crate.

[JSnover]

That's why the dimples are so apparent. The round shape sags more in the middle than a thin bar.
That's all the proof I need: Change your mold, your previous indicators are pretty near useless.

[RogerDat]

The tendency to sink in the center while less apparent in some ingot molds than in others it Will be fairly evident between different alloys in the Same molds. In a 1.5 lb. angle iron bar ingot it might be hard to spot the difference between WW's and WW's + 1.5% tin but WW's and Plain will be fairly apparent.

Of course just tap two of them together, plain goes thunk, WW's goes more tink,, adding a bit of tin won't change that sound much. Lyman #2 is probably enough different to detect. Either from dimple, sound, hardness or just appearance in general. Eventually the differences will make spotting similar alloys with some accuracy more likely.

Or oh yeah reading what I wrote on it with a sharpie :-)

[konsole]

Pure lead (soww) ingots will sink-in much more then less pure lead (coww). The larger the ingot the more it will sink-in. If you have ingots that are 5-lbs+ you could even see the sink-in cause cracks around the hole. You should see how much pewter/tin sinks-in if you pour a larger ingot of like 5-lbs, the holes are narrow but they appear to never stop getting deeper. That to me would indicate that its the antimony that stops the coww ingots from sinking in that much. I've noticed that if I drag a spoon or spatula across the surface of the molten lead after it has been poured into the mold, the resulting ingot will have a top side that has a different texture, and does look like the "thumbprint" your talking about. Remember that there is atleast 1 style of soww that is considerably less pure then the others, the sticky thread with the xrf scan shows it. Those I put in with the coww because they are closer to coww alloy, and if you do mix them in with your soww then the resulting ingot will end up with a little bit of frosting or crystalline shape specs. soww ingots should look dark, sink-in considerably on top (size dependent), have a semi-mirror finish, and just have this overall feel of being very soft for a metal. coww should look brighter, not sink in that much in top, have a frosted look almost as if its covered in very fine glitter, and just have a feel of having a hardness of an actual proper metal.

[RogerDat]

I think there is something distinctly different about how Konsole and myself make ingots. I do large ingots in bread pans, weight at least 10# with some going 16# and while I can see some difference in how the ingot finishes and the way the exposed part cools I don't see the extremes he describes.

I have no idea what exactly would be the difference that leads to the different results. I use a cast iron dutch oven over a propane turkey fryer burner. Melt at around 650* - 700* for mixed alloys, 725* - 750* for plain lead. Tend to do the large ingots when doing large batches. Big batch of sheet lead or mixed bunch of lead ingots. When I want to get a xrf gun check of the batch to confirm what it is before deciding what I'm going to do with it. Would rather pour some big blocks until I know what I have for certain.

I think that might have been the point being made by some of the prior posts - how it looks "depends" and thus is not a reliable way to determine or keep track of alloy content of an ingot.

[Chris24]

Pure lead (soww) ingots will sink-in much more then less pure lead (coww). The larger the ingot the more it will sink-in. If you have ingots that are 5-lbs+ you could even see the sink-in cause cracks around the hole.

I've seen the cracks on some of my 2 pound ingots that cooled really fast.

[mfraser264]

The sink or dimples you see is actually shrink if you were talking in the casting industry. The perimeter of the ingot (regardless of the size ratio) contacts the metal of the mold and begins to solidify and works back to the center. As the metal solidifies, it pulls metal from the molten area or the center lessening the volume of metal in the middle of the ingot. This is why the center solidifies or gets hard last as it remains hotter the longest. It is expected that the middle would be less thick or dimple. In pouring castings, risers (extra molten metal) are used to supply more molten metal to the casting to keep this defect from happening. One of the first things learned in casting that all castings have some level of shrink. Melt a 1" cube of metal and it will not fit in a mold that is exactly 1" even with dimensional shrink. Metal expands when in the molten state and is larger in area too. This is from having worked in 4 casting facilities over the years and is common to almost every casting process..

[konsole]

Rogerdat,

I use bread loaf pans also, the ones that are about 5" long. Those things make a really nice size 5-lb ingot, though the thin steel sides of the mold will warp slightly when filled with molten lead and give the ingot a slight concave/convex surface. What I consider a significant difference in look between ingots of each type could be viewed by someone else as not really that significant. I do think the difference is large enough to call it significant, and I could tell what an ingot was (coww/soww) if I forgot to label it or I was looking at it from 25 feet away. If I had 1 of each I would take a picture but I don't have any right now. Something about my ingots that I don't think is debatable is that I get strong consistency in how they look. In other words all coww ingots look practically identical, and all soww ingots look practically identical.

[RogerDat]

With things casting consistent technique tends to yield consistent results.

The point that mfraser264 makes about "risers (extra molten metal)" is exactly why when casting a bullet one has to leave a sprue puddle on top of the mold. The puddle provides the "extra" molten metal that gets sucked in. Often one can see a dimple in the sprue as it hardens.

I think possibly the volume of lead I'm using makes a difference. Generally 2 or 3 times the amount, more heat slower to cool and solidify, more time for metal to migrate. Top can radiate heat as easily if not more so than the sides. Bottom sitting on wood probably slowest to lose heat. I get less of a dimple more of a ridge around the edge and a broad center that is slightly depressed all the way from edge to edge. Bit more in the middle but the difference caused by contraction is spread out so less apparent.

As I said I only use the bread loaf pans when I'm doing stuff in bulk typical is 4 scoops from a 4# ladle. Without much concern for having each scoop level full or even consistently full. Just want this 100# of small "stuff" into bricks so it will stack until later. It is even possible that some of the most extreme contraction and edge cooling takes place before I'm putting in that last ladle so the last one acts as the "riser" that was mentioned. I think I'm going pretty fast but lead does go solid pretty fast.

[bangerjim]

If you are getting dimples/cracks/distortions in your ingots, please stop what you are doing and send them ALL to me for evaluation! [smilie=w:

We just cannot tolerate those defects in ingots, can we???????????

[Chris24]

I just poured some really hard, frosty COWW ingots today. No dimples whatsoever. They must be the older high antimony alloy. Very nice surprise!

[RogerDat]

Banger I would love to see folks accommodate your request that these defective ingots be sent to you for proper remediation and/or disposal for the ones that can't be salvaged. However I like to encourage people to stomp their own snakes so I'm going to suggest people get out there and scrounge more lead, cast more ingots until by gosh and by golly they get it right each time, and every time! I hate to see you burdened with more alloy to test and cast while I appreciate your willingness to help other members out.

Failing to produce perfect large ingots I suggest they go back to basics and cast smaller round ingots of say 100 grain to 350 grain depending on what smaller ingot molds they have available until they have worked through any issues with alloy and technique.

However in the event the above does not work out and you live on the East Coast, in the South or Midwestern state you may find it more convenient to send them to a closer disposal site I have here in Michigan. Save postage and transportation costs and all that. Package in MFRB not over 55# and PM me for an address to send it to. If you live on the West Coast you probably have zinc so go ahead and send it to Banger in Arizona.

:kidding:

[Chris24]

I smelted yet another bucket of COWW today. These made an odd layer on top. Lots of gold and orange, and even blue oxides. I fluxed it several times, and the oxides finally reduced away. I tested a sample for zinc with sulfuric acid. There were no bubbles. I think this is a high tin content batch. They filled the molds well with no dimples, but don't look crystalline like antimonial lead.

[Retumbo]

I smelted yet another bucket of COWW today. These made an odd layer on top. Lots of gold and orange, and even blue oxides. I fluxed it several times, and the oxides finally reduced away. I tested a sample for zinc with sulfuric acid. There were no bubbles. I think this is a high tin content batch. They filled the molds well with no dimples, but don't look crystalline like antimonial lead. Those colors indicate pure/next to pure lead

[Retumbo]

So what about these dimples? Aloy seems to be very hard 20bhn. I got lots of experience with wheel weights but not other aloys

147414

147416

[Chris24]

Those look odd. You didn't get some zinc mixed in, did you?

[Retumbo]

Those look odd. You didn't get some zinc mixed in, did you?

When in liquid form the alloy looks like normal lead, shinny and no lumps, no "oatmeal"

[RogerDat]

That surface does not look like anything bad the smoother ingot has what looks like the "buttery" surface of some printers lead or other good alloy. Which might explain the 20 BHN. I don't know about that rough textured looking stuff if it was the same batch as the smooth stuff I would suspect some off gassing or dross in the pour caught coming to the surface. Or possibly a patch of some concentrated x material?

Do both samples have the same BHN and come from the same batch?

[Retumbo]

Scored a bunch of lead in soup cans.I melted each soupcan seperately. I got two seperate types of lead. Both are very hard, have not measured the hardness of the porous one. Maybe I'll reheat and flux a couple more times.

[RogerDat]

Scored a bunch of lead in soup cans.I melted each soupcan seperately. I got two seperate types of lead. Both are very hard, have not measured the hardness of the porous one. Maybe I'll reheat and flux a couple more times.

Soup cans. Now that is a new one to me. If they are both really hard you might want to see if a scrap yard in your area will gun the ingots. 20 BHN is significantly harder than plain lead. Do post what you find out about the porous one. Interested in learning from your investigation.