Odd melt with old Fishing Net weights

[akajun]

Friend gave me about 30lbs of old fishing net/shrimp trawl weights that he has collected over the years. They were all used in saltwater and were pretty oxidized. However preliminary tests past history tell me that they are close to pure lead. Anyway while smelting them I would get a lot of "oatmeal" type dross similar to zinc, even though I know there was no zinc weights. No dirt in the dross or melt either. However I scooped out the oatmeal and poured my ingots. Ingots test on my lbt tester similar to pure lead.

However I noticed that the dross I skimmed was now solidified into a solid blob so I decided to put it back in the pot and left it there for an hour. When I came back and stirred, I got a lot of ash and dirt, and was left with a 1lb ingot of lead.

What have I got and what happened?

[mold maker]

What you using for flux?
I've had the same thing happen with lead pipe that had lots of oxide. I didn't leave mine quiet that long, but with saw dust, a lid, plus a little more heat it soon came out just powdery dross and lead.

[akajun]

I did not flux (sawdust) until after pulling out the oatmeal. I was paniking trying to get what I thought was zinc out.

I used no flux in the second melt of the dross either.

[P.K.]

Thinking salt.

[jsizemore]

I didn't see in your post about your smelting setup. You didn't mention specific temps so no thermometer. Your melt didn't seem to get too hot because no mention of color change on the surface of the melt. If the temp is slowly rising on the melt then you could have a longer slushy stage which a lot of folks confuse with zinc contamination. Since you scraped it off the top of your melt and then remelted and got more lead leads me to think that's what happened. After an extended length of time you got your 'reclaimed' ingot and found some light dust on the surface of the melt. That could have been whatever was used to alloy such as tin or antimony. No doubt some dross too. Any loss due to oxidation can be reduced by fluxing before you remove it from the melt. I started smelting with a thermometer and learned what it was I was seeing as the melt progressed. Now I rarely use the thermometer except to confirm what stage the melts and when surprises happen. Folks at the scrapyard are good to me but don't always know what's what. At 25cents/lb I can live with it.

[geargnasher]

Like others have said, it's probably caked-up layers of lead oxide floating on top, and merely needes to be chemically reduced to lead again. Any kind of grease/wax/oil will do this quite well, and sawdust makes an excellent true "flux" to remove impurities and the carbon it produces also helps the reduction of oxides.

Gear

[cdet69]

Saw dust as flux? How does this work? Any particular wood you use? Seems a super great idea if it works. Thanks

[Justinsaneok]

What kind of saw dust? I heard not to use pine. Because the sap or something ? Someone who knows chime in at any time. I found this thread with the search function.

[jsizemore]

Sawdust that is not wet or from treated lumber is what you shouldn't use. You can use a stick, painter's stir stick or sawdust to flux. I use a piece of split heart pine and use it to flux and scrape the bottom and sides of my pot to release any traped dross and the carbon from the sawdust or stick reduces the oxidation back into the melt to reclaim the lead and other metals in the alloy. Sawdust,beeswax, motor oil or any carbon based item can be used just make sure there's no water.

[cbrick]

cdet69, Justinsaneok,

Read chapter 4 on fluxing and all your questions on fluxing will be answered. I highly recommend the entire book but chapter 4 is on fluxing.

From Ingot To Target (http://www.lasc.us/Fryxell_Book_textonly2.pdf)

Rick

[akajun]

Sizemore, I think you may be right. I did not put my thermometer in the pot, however using a thermometer before I know I need to let my old lee pot at #7 to get it around 650 to 700. MY method for smelting is to dump a load of lead in, and come back 20 miinutes later stir and flux. Using this meathod I have never had a problem until I got these fishing weights. Previously I had smelted 100lbs of window came that day the same way with no problems, and it was some dirty stuff too, full of glazing, rust, broken glass, etc.

BTW I use a special sawdust to flux. It is only available in one place and has magical properties. I open the door to my tablesaw and grab a handfull of whatever is in the bottom. It is mostly pine, some cypress, and very little hardwood.

BTW I have fluxed with a pine stick before, I realy dont think that they type of wood matters, other than not using treated lumber because of the chemicals. After all Rosin is used as a flux in a lot of solders and I believe that is made from pine sap.

[xr650]

What kind of saw dust? I heard not to use pine. Because the sap or something ? Someone who knows chime in at any time. I found this thread with the search function.

Pine is the only sawdust I use.
Someone posted on here some time ago that pine resin/sap was chemicaly perfect to flux lead. I don't know if this is true. I have collected dryed sap off pine trees and used it for flux. Works well, smells great.
I also use a split piece of pine to stir my melt with.

[Suo Gan]

za za za za ZINC!!!! Been there and done that with fishing weights myself. How do you know there was not zinc in those weights? This is what zinc does to your pot after all. It bubbles and foams. I ruined a hundred pounds of alloy using large fishing weights once. Live and learn.

[akajun]

This didnt bubble and foam, just looked lumpy. Also what I salvaged from the dross was definatly lead as I tested it with my lbt tester, it was dead soft.
. Also these are not fishing weights, they are net/trawl weights. They are made to be crimped onto the net after it is woven. I dont think you can do that with zinc, it would crack.

[Springfield]

Flux is the key sometimes. I get that lumpy stuff on top, especially with sheet lead as it has lots of impurities in it. I get lumps, so I flux some more, still lumpy, more flux, still lumpy, more flux then PRESTO! it all goes back in except for the ash on top. As I never let the temp over 675 I know it isn't zinc.

[jsizemore]

The linseed oil in the old glazing was your fluxing agent. Also the layer of dross on the surface of the melt acted like a lid on your pot. Even though you used the same heat setting for both the came and fishing weights the insulating layer provided by the came's dross allowed the melt temp to run a little higher. That's why the came never showed the slushy layer on top of the melt. Most of the came ingots I've used to cast act like my 50/50 lead/coww when cast for my 45acp. Bhn runs about 8-9.