Bullet Inclusion Help

In an effort to step up my casting game I recently upgraded from a cast iron dutch over and a turkey fryer with a bottom pour ladle to a brand new Lyman Mag 25 Digital bottom pour pot. I've had a lot of success with that method. I thought surely that adding an electric bottom pour pot with a PID would only help. That's where my issues started.
As soon as I got the unit I let it burn off the oil with no lead in the pot per instructions. I've casted with the pot twice now running probably 60lbs of lead through the pot. I keep getting what I can only describe as inclusions in my casts.
At first I was getting terribly wrinkled bullets and I chalked that up to me over oiling the molds. I took my molds and washed them with hot soapy water and sprayed them down with brake cleaner. I preheated my molds on a hotplate and set the furnace to 800 degrees and started casting. Those changes helped the wrinkles some but I'm still not getting satisfactory casts.
My alloy is mostly old plumbing lead pipes and drum traps mixed with clip on wheel weight all hand sorted and fluxed with saw dust and paraffin wax. I fluxed the lead in the Lyman pot several times with saw dust and bees wax thinking that perhaps I had some contamination in the pot. I emptied the pot to see if there was any obvious contamination in the unit, none that I could see.
So, those are the facts and I still have no idea what is causing this over 4 different molds. Out of the 60 or so pounds I've run through the unit I've gotten perhaps 50 or 60 keepers. I've attached pictures of the defects along with an ingot that I poured from the pot. This just has me scratching my head. Let me know what you guys think. Thank you.

Picture of the offending boolits in question

https://i.imgur.com/BNQAhN7h.jpg
https://i.imgur.com/LbbzzXhh.jpg
https://i.imgur.com/NLrcwUnh.jpg
https://i.imgur.com/DNUIRp2h.jpg
https://i.imgur.com/ZylGa5Gh.jpg

Picture of a lead ingot drawn down to empty the offending furnace

https://i.imgur.com/wXrht6mh.jpg

And a few pictures of some good boolits to show that I'm not a total noob and because I want to show off a little.

https://i.imgur.com/ndwy7Uah.jpg
https://i.imgur.com/1Q4RtOQh.jpg

Thanks again for your help.

I had similar problems and mine was zinc in the wheel weights. I drained the pot and use pure lead with approximately 15-20% lino with 2% tin. No more voids. Good luck. Wheel weights were the best material yrs ago but nowdays its a krap shoot as to what is in them. Thanks a lot EPA, for saving us from that terrible lead(which was in the ground to begin with)

I thought about zinc. I tested each wheel weight with a side cutter before it went into the melt. Also my melt in the pot has a mirror sheen on top, no "oatmeal" and I seem to be getting sharp corners and good fill out in most of the mold. Just doesn't seem to have the characteristics of zinc contamination. I could very well be wrong though. Thanks for the input.

Quote: My alloy is mostly old plumbing lead pipes and drum traps mixed with clip on wheel weight all hand sorted and fluxed with saw dust and paraffin wax. I fluxed the lead in the Lyman pot several times with saw dust and bees wax thinking that perhaps I had some contamination in the pot. I emptied the pot to see if there was any obvious contamination in the unit, none that I could see.
------------
To clarify, you did or did not smelt your scrap alloy in the casting furnace? It is hard to get a good vertical movement of the alloy when fluxing and reducing in a casting furnace.

The only thing I cast at 800 degrees is pure lead. I usually run about 720 for COWW and blends of that and soft lead with tin added. You might be making more dross by running this hot.

It does look like specks of contaminant. It could be just oxidized alloy that get carried to the bottom of the pot when sprues or ingots are added to the melted lead. I get them a lot toward the end of a 60 or 70 pound casting session out of my Mag 25. I clean out the pot and flux the lead in a different pot before returning it to the Mag 25.

You didn't mention adding any tin to the mix. Tin helps the metal flow and fill out. It dosnt take a lot but can make a big difference in the finished product. You might try 1% tin added to see if that helps out. Also flow can become an issue with a bottom pour pot. The ladle fills the mould quickly while the metal is all still molten. Sometimes the bottom pour is slower and the bullets nose and front portion start to cool solidify before pour is done. The Lyman pot should be more than capable here. I would turn down to 725*-750* preheat the mould good and experiment a little Pour speeds casting cadence, gravity pour, pressure pour, straight in to mould thru hole. on edge for a swirl, angled mould and straight mould. I would consider adding 1% tin to the mix also.
Making your alloy in the casting pot can cause several issues, 1 it introduces more crud and dirt into the pot when starting. It adds the clips and possibly undesirable weights into the pot. Its a small Batch and more care needs to be taken to replicate the alloy on every pot. Resurrect your dutch oven and turkey frier for smelting and alloying. This makes a bigger batch and is an easier pot to flux mix and clean. Pour this into clean ingots and label as to alloy and pot number. If you make 5 pots of a given alloy and pour 1 lb ingots then in your 25 lb pot 5 ingots from each pot every time makes a simple exact alloy every time. And since its 5 bigger pots it lasts longer in the casting pot before more needs to be blended. You flux several times with wood shavings and paraffin remove clips and dross, flux one or 2 more time and pour ingots. This makes very clean consistant ingots for the casting pot.

All dirty lead processing was done in a dutch over over a turkey fryer that is used only for processing dirty lead. Only what I considered "clean" lead ingots went into the furnace. I tried running it at all different temperatures from 700 - 850 with no noticeable difference in outcomes. Thank you very much for the help thus far.

Do you use saw dust in the casting furnace?

Quote:

---

Originally Posted by Dusty Bannister

Do you use saw dust in the casting furnace?

---

I have used sawdust in the furnace hoping that it may help to clean out any contamination that may have been in the pot. I also used sawdust when I would cast from a dutch oven and a bottom pour ladle I had no bullets that looked like this. Now granted, that was a different batch of alloy. But my molds would just rain keepers using that method. If it is contamination in the pot what is the best way to go about cleaning it?

I use only wax for flux in the casting furnace. Sawdust and wax together can stick to the pot below the surface and migrate to the spout as waxy charcoal specks. The cast iron smelting pot gets sawdust and wax until the alloy isclean. If you only introduce clean lead in the casting pot it reduces the possibility of contamination. That appears to be part of your woes.
I suspect you need to increase the flow into the mold.
At least two of the boolits pictured show definite cooling in stages caused by either too slow a delivery of alloy, too cool a mold, or both.
Every change in equipment or alloy has a learning curve even if it's a vast improvement.

Ditto on the wax/boolit lube. I've used a small piece of Lyman beeswax/alox lube cut into a small doughnut for years and it worked like a charm. Just remember to light the smoke with a match to keep it from smoking your shop up.

I tried again last night. Same issues after wax fluxing. I turned up the heat up to 800 and cast as fast as I could. They got better but not where I'm used to. I think the problem is that I've tapped my supply of WW lead. I mixed the last 7 or 8 pounds of COWW lead I had with probably 70-80 pounds of reclaimed plumbing lead. From some of the comments I'm seeing here it's making me think that perhaps I just need some tin and antimony in my alloy. Looking back it's mostly pure lead. Could that be causing the kinds of issues I'm seeing? Thank you all for you help thus far.

"Looking back it's mostly pure lead. Could that be causing the kinds of issues I'm seeing?"
No, That would only cause rounded corners, but never did for me when I used 50/50 coww and soft lead. The only time I have gotten what you show is with impurities in the lead.

Quote:

---

Originally Posted by farmerjim

"Looking back it's mostly pure lead. Could that be causing the kinds of issues I'm seeing?"
No, That would only cause rounded corners, but never did for me when I used 50/50 coww and soft lead. The only time I have gotten what you show is with impurities in the lead.

---

So are we thinking resmelting the ingots and fluxing the fire out of them with saw dust? I've used some pretty dirty lead before and it always came out clean after 3x sawdust flux and hit it with paraffin wax. This lead wasn't noticeably dirtier than other lead I've processed. Or is it possible the contamination is just so fine that I have no hope of cleaning it up and need to just sell it as ballast or fishing weight lead?

Try playing with the volume and height of the nozzle to the sprue plate. If the lead stream comes out too slow and stringy it could cause those specks to form.

Those black specs in the melt are likely the result of not getting all the burned saw dust out of the melt when stirring and skimming. I would not expect that to continue to add it to the melt is ever going to help remove it. What happens when you stir the pot in a circular motion for a several seconds and then let it set for a few minutes? Is it possible that there is a problem with the technique you are using. There are stickies on this. I thought Saw Dust was used to "reduce" and wax was used to flux? I have been wrong before.

Try looking at posts about removing zinc with copper sulfate. It seems to work. But read and follow the cautions

Do me a favor, try one of those molds again, don't run it quite so hot, preheat your mold.

And however long you are waiting before you crack the sprue, try twice as long.

Me I like to watch the metal change from liquid to solid, then count to 5.

I think what your seeing is the sprue plate "pulling" lead that is a bit too warm to cut clean. So it kinda grabs a little chunk. Letting it cool just a little longer just might be all you need to fix this.

My $.02. You are over fluxing and keeping the contaminants in a suspension. You are getting some slight tearing of the sprue when you open the mold. But that has nothing to do with the contaminants you are seeing. Try heating up the pot and let it sit for 20 minutes or so. Ladle off the dross and put a small amount of flux in the pot. The melt should be hot enough to allow the smoke from the wax/boolit loob flux to catch fire or readily burn if a match is thrown in the pot.

Alright, update time. I don't have internet access at home so I'm sorry I haven't been able to respond to all your suggestions. I remelted and refluxed all 150# of lead that I had . The black spots seemed to have gone away for the most part. I'm still seeing some here and there. I'm still not getting good fill out and I've yet to get a decent bullet out of my NOE 452 HTC. I just bought a new Lee 452-200-SWC 6 cavity that I finally got some keepers out of after casting like a mad man at 750 degrees. It took the bullets frosting to get good fill out. Is the bottom pour pot ready to cast as soon as it reaches temperature or do I need to let it set at temperature for 20 minutes to let the whole pot warm up? I did not add any sawdust at all to the pot this weekend, only beeswax. I'm starting to think I had multiple problems. One being sawdust in my lead like someone suggested, still not sure how to get that out. The other problem may be burned on oil in my mold cavity. Working on that now. After brushing with hot soap and water, brake cleaner, acetone soak I'm still not getting good bullets. I boiled the mold in water and dawn for about 20 minutes then dried in an acetone bath again. We'll see how that goes. Thanks for the help again.

The sad thing is you may try time after time and suddenly the problem disappears without you knowing why. A little lino (to harden and fill out) added will likely help. Once you get the melt level down in the pot, a good scraping of the pot surfaces should float what contaminates are left.
The speed you fill the mold and actual mold temp will be close to your past experience. Changing to a bottom pur doesn't alter that..

Another thing to remember with a new mould is it make take being heat cycled 3-4 times or 3-4 casting sessions to "break In" and cast its best. This break in is some burning impurities out of the blocks and more developing the patina that helps them cast so good.

Likely that the marks you see are from the towel or whatever you're dropping the boolits on.

After the though cleaning that you do with Dawn and Acetone soak, it takes 2 or 3 casting seasons to develop the patina that gives good boolits.

Heat the mold up and cast a few boolits till wrinkles are gone, let the mold cool down and repeat.

The third casting session should give good boolits after the mold gets up to temp.

Preheating the mold on a hot plate will help a lot in getting good boolits.

Lafaun

I would clean up the mix again.

It don't take much to make some bad ones.

It sounds like heresey, but when a mold makes me have fits I'll spray the bejezus out of it with RemOil, and in a few more casts I'll have good bullets.
I flux with a small piece of bullet lube or beeswax, stirring fairly quickly and deep, and throw a kitchen match in the pot to burn the smoke off. It works for me.......

I cast a lot of range scrap & no issues. When I get a new mold, it does take awhile, even after cleaning, for me to get good bullets 100% of the time. generally fluxing often helps. For me during casting, that is just stirring often with a wooden stick or spoon. Sometimes adding just a bit of tin helps a lot with mold fill-out. I cast about 700deg.