Lead replacement?

[Fernet]

A big thank you to you all for the great info. I'll try to get a hold on some Bismuth an try the 90-10 blend. When saying it is brittle I hope that doesnt mean to brittle and wont hold together when smashed into the rocks?

Experimenting with new alloys may have been a bit naive and not well tought thru. I'll leave that for someone else better suite for the task.

[Ogajiga]

"Fernet", if "smashed into the rocks" above water is one of your techniques, you might consider adjusting. Even harder 60-40 is brittle enough to fragment with sufficiently hard impact, and 90-10 is more likely. A good tough powder paint job of course will add to the strength of any casting, including soft lead which easily dents out of shape. Although I don't get much water time anymore due to work load and geographical location, most of my fresh water time is spent shorelining jigs on rock dam faces, rocky bluffs, and boulder strewn streams, and I may have broken 1 jig head, which I really don't even remember.

[Fernet]

Hehe. No, I usually try to avoid that. But I'm aiming at selling my creations in the future and who knows what rough treatment the will suffer. Dont want disapointed customers. I will probably put an additional expoxy coat on top anyways for holding the eyes on place.

If with "fragment" you mean small pices coming off that aint to bad. My worries were more if the lure might break into thousand pieces like that fellow in Terminator.

Edited April 14, 2008 by Fernet

[Fatman]

Hawn,

Yeah I've already checked with Lee Precision Pots as I have 2 of the Production Pot IV's. There answer to me was.

"The Pots should not be used for zinc,copper, silver, gold ,

aluminum, pewter or brass."

and to the mix ration for bismuth tin they answered:

"The ratio of Bismuth to Tin would be better if it were closer to 50-50

or slightly more Tin than Bismuth."

but I'm looking at that ration as being WAY lighter than the 60 bis/40 tin. I'm gonna give the stuff a try as I'm really only using it for split shot/small sinkers and to try on a few jigs. I don't powder paint alot anymore as I still use the old testor's paint then a clear coat of epoxy.

Couple pounds can't hurt (well maybe) but I'd really like to only carry one box everywhere I go.

Fatman

[Ogajiga]

"Fernet", the reason I don't remember breaking a BiSn jig head isn't due to bad memory, its probably that it never happened. I just took a 1/8 tube head which I believe is a 7-1 mix and threw it down hard on concrete several times with no chips or any visible damage. "Fatman", split shots made with a Bi alloy will only be useful as sling shot ammo - only pure tin is soft enough to open/close. I notice that Lee didn't list tin or bismuth on their no-no list. One of our lurker members (Howzit Nellie!) is commercially casting tin in his Lee pot. Don't let the #s scare you away from trying BiSn heads. Since I switched totally to lead free in fresh water 4 years ago I don't even remember what lead weight feels like and think I get my fair share of catches with no problem.

[Vodkaman]

Bi_Metallic Corrosion ( Galvanic Corrosion ) this article shows a table of metals, showing how they corrode together.

If the pot is cast iron, in each case, the other metal is the one that corrodes. My point is that, if the cast iron is not reduced by corrosion, what is the problem?

Just curious.

[sagacious]

"The Pots should not[/b'] be used for zinc,copper, silver, gold, aluminum, pewter or brass."

Bi_Metallic Corrosion ( Galvanic Corrosion ) this article shows a table of metals, showing how they corrode together.

If the pot is cast iron, in each case, the other metal is the one that corrodes. My point is that, if the cast iron is not reduced by corrosion, what is the problem?

Just curious.

Dave,

The issue isn't one of corrosion, galvanic or otherwise. In the case of several of the metals on the do not use list, the culprit is erosion.

The reason that zinc plating (galvanizing) works so well, is that when you dip clean steel into molten zinc, the zinc actually forms an intermetallic compound (alloy) with the surface steel. Put another way, the zinc is actually fused to the steel, and is not just a separate surface layer. Not all metals will do this, but some will.

Those that can form an alloy this way will actually dissolve the other metal, regardless of it's melting point-- exactly the same as water dissolves sugar without needing to melt the sugar. So, molten zinc will slowly and steadily dissolve or erode steel. The inside of a steel pot used to melt zinc will soon have a layer of zinc permanently fused to it, and dissolving it. If you don't pay attention, eventually you'll get a pinhole stream of zinc spurting from the side or underside of the pot. Not good. Let me tell you, it gets your attention pretty quick!

I have no experience with melting gold, but all those metals (except pewter, as far as I am aware...) have the potential to readily attack and erode the steel liner of the pot. I sincerely doubt that your average lead pot stands any chance of melting most of these metals, but better safe than sorry, I guess.

Hope this helps, take care.

[Ogajiga]

That explains why cheap and reasonably workable melting point zinc sinkers aren't seen much. Given the appearance of the rotten zinker I found and now knowing zinc's tendency to dissolve in water with any salt/acid constituents I'm not convinced it's a suitable metal for lead replacement especially in low circulation enclosed fresh water bodies.

A final word on my experience with whole number ratio BiSn alloys from 9-1 to 1-1. All hand poured OK with increasing amounts of tin pouring tiny jig heads easier. Higher bismuth percentage = heavier alloy of course ranging from 83% to 75% lead weight. Higher bismuth also means higher melting point with the lowest at 58-42, which is the lowest amount of bismuth I suggest using in your fishing weight alloy. Higher tin toughens the alloy more, but reduces the melting point again down to 58-42 as the lowest. My original standard alloy was chosen as 7-1 although there wasn't a significant difference in pourability between 9-1, 8-1, 7-1, 6-1, or 5-1. Maybe 7 sounds luckier. When the cost of bismuth tripled I was forced to drop my bismuth content down to 58-60%. Downside is the alloy is lighter and not powder paintable. Bismuth price has increased several times in the past month, advise perhaps buying in ASAP if you're interested.

Edited April 16, 2008 by hawnjigs

[Vodkaman]

Thanks Sagacious, I guess I was in the pub when that lecture took place.

[sagacious]

That explains why cheap and reasonably workable melting point zinc sinkers aren't seen much. Given the appearance of the rotten zinker I found and now knowing zinc's tendency to dissolve in water with any salt/acid constituents I'm not convinced it's a suitable metal for lead replacement especially in low circulation enclosed fresh water bodies.

...

This is certainly true of pure zinc or anode zinc, but many zinc alloys are a different breed of cat. A small change in alloy components may result in a major change in physical and chemical properties-- not unlike steel. Common zinc casting alloys such as zamak (Zn, Al, Mg, and Cu) have good corrosion resistance, and are often used for marine fittings on boats.

Thank goodness we have lead and tin to work with! I have no need for an alternative to lead, but if I did, based on my experience with it, I might very well be working with zinc. Zinc alloys have the advantage of being fairly tough and hard, but are still relatively inexpensive and easy to work with. A neighbor friend of mine casts several-ounce zamak jigs and sells them informally during the summer at garage sales. They do catch plenty of rockfish.

Back when I was working with zinc, I used stainless crucibles to melt the zinc or zinc alloys in. Most anything stainless would do. Ordinary drawn steel or cast iron melting pots weren't up to the task.

In the environment, free zinc is eventually changed to zinc oxide-- the same stuff you take in lozenge form to reduce the effects of the common cold. Lead does the same, forming the toxic compounds lead oxide and chloride, but unless you're a bird and grind it up in your crop, these compounds by themselves are not bioavailable and not water-soluable.

Hope this helps, good luck.

[Ogajiga]

I was wondering if alloying zinc would retard oxidation. You zinker tinkers are a tough breed - those alloy metals require too much heat for my comfort(and fuel budget). "Sagacious", do you know what the melting point of zamak is? How do you remove such a tough sprue? Can you pour in standard molds? I occasionaly pour 3-5 oz. SW jig heads and the heat of lead melt destroys the tin plate on hook eyes. Yes thank goodness for lead & tin, and with rising fuel costs I appreciate my low melt BiSn alloy requiring less than half the fuel of lead casting.

[sagacious]

I was wondering if alloying zinc would retard oxidation. You zinker tinkers are a tough breed - those alloy metals require too much heat for my comfort(and fuel budget). "Sagacious", do you know what the melting point of zamak is?

Yes, your instincts were correct, the zamak alloys have good corrosion resistance. The melting point of the zamak alloys is about 725*F (385*C). That's about 100 or so degrees F above lead, so it's do-able, but those addidtional 100 degrees should not be dismissed out-of-hand. It does require additional effort and safety precautions vs working with lead.

How do you remove such a tough sprue? Can you pour in standard molds?

You can snip the sprue with dykes or wire cutters. I took a pair of dykes and ground the 'flat' side completely flat-- like gate shears. It's stronger than regular gate shears and that cuts the sprues nicely. I use them for lead as well. You can pour in regular metal molds. Smoke the cavities before each pouring session, or use a stearate spray-on mold release.

If the sprue is designed correctly, you can snap it off like you do with lead. Zinc is hard, but not that hard. The real hassle lies with mold pre-heat, and dealing with overpours. An overpour that locks the mold closed cannot quickly and easily be unbent from around the mold-- like you could with lead-- both because the mold will be really hot, and the zinc flashing needs to be manipulated with pliers. Not fun.

I occasionaly pour 3-5 oz. SW jig heads and the heat of lead melt destroys the tin plate on hook eyes. Yes thank goodness for lead & tin, and with rising fuel costs I appreciate my low melt BiSn alloy requiring less than half the fuel of lead casting.

Yup, if tin was cheap, wherever possible I would substitute it for lead. The lower the melting point the better, and tin is just 'nice' to work with. I pour jigs from 3 to 24ozs, and hard lead is really the only thing that will get it done. Aside from tin and tin alloys, most alternatives to lead have a number of challenging hurdles to overcome.

Hope this helps, good luck all!

[sagacious]

I occasionaly pour 3-5 oz. SW jig heads and the heat of lead melt destroys the tin plate on hook eyes.

An afterthought...

If you're still pouring those 3-5oz jigs, you may be able to remedy the heat damage done to the tin plate on the hook eyes. There's an inexpensive product-- as miraculous as it sounds-- that will stop heat transfer in metal. Non toxic, no fumes. Could be that dipping the hook eyes in this will solve the damage: HEAT STOP TM HEAT CONTROL PASTE at Brownells

Good luck!

[Fatman]

So Hawn with your experience in this would you recommend the

60% bis/ 40%tin or a 58/42% mix???

I'm leaning at the 60/40!!

Thanks for letting me know about the tin for split shot, maybe I'll just give up thinking about those and buy them, hopefully leaving more money for the lead-free material.

Fatman

[Ogajiga]

"Sagacious", call me sloppy but I often do overpour into the mold hinge area and that would be a nightmare to free up from hard zinc alloy. I don't think I would mess with zinc unless desperate with no other alternatives. Good tip on creating a tool steel sprue cutter. My two light duty gate shears are starting to look like saw blades at the cutting edges due to hard alloy trims.

"Fatman" 3-2 60/40 BiSn would be easy to measure out & alloy together. Weigh your tin then break the brittle bismuth with a cold chisel to measure 1-1/2x your tin weight. You probably figured this out already. Its improbable to make a precision 58-42 alloy in a home shop anyway due to different hot & cold oxidation properties of the two metals. If you want closer to lead weight don't be afraid to try 9-1, 8-1, 7-1 etc. BiSn alloys, though their working temps will be higher than 60-40. Although (shiny)tin split shots are Do-it-able, you can't beat low vis black tin Dinsmores.

Edited April 17, 2008 by hawnjigs

[Ogajiga]

An update on BiSn alloy composition cost strategy. I reduced the Bi content of my alloy when Bismuth zoomed to $18.50 while Sn(tin) remained at $8 per lb. Well, now with Bi at at $19 and Sn around $15 there is substantially less cost savings for alloying lower Bi. For those who want max weight and powder paintability might as well go with higher Bi.