melting/pouring lead

[Fritz Koschmann]

I have to pour 65 pounds of lead into a centerboard. I am aware of the many dangers associated with this but I have some practical questions. I have the lead in the form of round commercial fishing trolling weights, one of which is around 65 lbs. Should I pour it all at once or can it be done in smaller pours. A practical problem is finding a pot large enough and then being able to handle it safely with 65 lbs of lead in it. Will a regular cast iron pot pour lead without dribbling all over? Should I use a ladle? Should I cut the round lead ball into pieces before melting? Any suggestions will be appreciated.

fritz

[Bob Cleek]

Molten lead is funny stuff. (Think solder.) It will take a long time to melt that round sinker from a standing start because only one point will be touching the bottom of the pot and the whole piece has to "sink" the heat until it reaches close to melting temperature around 750 or 800 f. IIRC. On the other hand, if you have some small stuff that you can get melted in the pot first, then add the bigger pieces, it is surprising how fast the heat will transfer once the melt is started. I guess this is because there is greater surface area in contact with the heat source. Once a fair amount of molten lead is in the pot, you can ladle some out and at the same time add an equal amount of cold lead and it will keep up with you easily.

Sixty five pounds of lead is less than the size of a shoebox, I'd guess. You should have no problem melting it in a cast iron Dutch oven or similar strong pot on a propane turkey fryer burner. You can ladle it out with a stainless steel kitchen soup ladle. That will come to maybe thirty dips, but hey, you aren't doing this on a production basis. If your lead is kept sufficiently hot in the pot, and you ladle it in steadily, you should have no problem with it cooling too fast. The first ladle or two may cool and harden on contact, but don't sweat that. As you add more molten metal, the heat of the mass will remelt the earlier material in the mold.

I would never attempt to pour sixty-five pounds of molten lead without a foundry crane and proper foundry pot! Drop her and yer dead meat!

[ 01-19-2006, 11:28 PM: Message edited by: Bob Cleek ]

[epoxyboy]

I cast the lead tip (about 55 pounds) for the centerboard of my Welsford Pathfinder as follows. I bought the largest cheapest stainless steel cake mixing bowl I could find at the local purveyor of cheap s**t chinese hardware - this got one side mashed into a bit of a spout. I sat that on the gas barbecue (cooking plate removed!!) and added small scraps of lead until there was a good half inch of molten lead in the bottom. Things went much faster after that. Once the lead was all melted (about an hour later) I put two F clamps on opposite sides of the bowl to use as lifting handles, and a third at right angles (opposite the "spout") to tilt the bowl with.
My lovely assistant helped me with the lift and pour into a concrete mold - I would NOT recommend trying to do this part on your own.
The bowl went into the rubbish bin after this.
The setup wasnt fancy, but was stable and as "safe" as I could make it. The end result was surprisingly good.

Pete

[Andrew S/Y Rocquette]

Camper and Nicholsons used to pour them up to several tens of tons with a rotating human chain with large ladles, and a pair of extra hands with gas blowtorches playing on the keel/mould surface to stop the it solidifying before the next batch was poured on, to ensure a homogenous end product with no cracks or flaws.

This process might adapt quite well to a smaller 2-person pour - one with the ladle, one with a blowtorch on the mould?

[Fritz Koschmann]

Thanks Bob and others for your replies.

I should mention that I will be pouring directly into a cut out section of the plywood centerboard. I have the cutout, backrouted?, so the lead will be locked in place. I have heard that waterglass can be painted onto the wood to prevent scortching? Seeing as how I cannot heat the mold should it be poured at one go?

fritz

[Tom Robb]

What everyone said.
Plus stay up wind of the hot lead and keep any pregnant females and little ones WAY far away. The fumes are likely to be more of a risk for them. The fumes won't do you any favors either.
The wood will scorch and the resins in it will bubble up. Maybe the waterglass thing might help that.

[willmarsh3]

I did almost exactly the same thing you are doing here (http://home.att.net/~willmarsh3/el/elver071804.html) . My fryer had no problem melting 30 pounds of lead. Just remember to preheat any piece before placing into the molten lead to drive off any moisture. Also instead of routing out the inside of the hole I used screws.

Good luck.
Will.

[landlocked sailor]

I recently smelted ~250 lbs of lead from old wheel weights; I used several pie plates. As the lead melted I skimmed off the dross. When the plates were ~3/4 full I turned off the heat and let them sit until the lead was 'stiff', then moved them to a concrete pad to cool and started a new plate. The resulting discs of clean lead weigh about 20-25 lbs each. Rick

[wyndham]

Fresh air and lots of it.
Like Bob said 65 lbs is not a lot of lead. Good gloves, be careful.

[landlocked sailor]

Yep, I did mine OUTSIDE. I did no pouring or ladling. Rick

[Ed Strong]

How much does the wood mold i.e hole in centerboard, burn? Is this a problem? Never have worked with lead before.

[ssor]

That will depend on how hot you get the lead. Check with a pine splinter. After it melts you can go on heating it until it boils but hot enough to char a maple stick is plenty hot enough.

[capt jake]

When it gets to the point of 'boiling', it will then begin to emitt the dangerous vapors. I believe it is around 650 when this happens. If you melt it and keep it just hot enough to pour (without getting it too hot) you will avoid that added danger.

I recently poured a weight into a Mahogany rudder; no charring at all.

[Jay Greer]

I would recommend coating the wood with Sodium Silicate, "water glass" to hold down the scorching. It's a shame they took the lead out of wine bottle foils. Us winos put 200 lbs. of foils into "Taliesen's"
keel when we poured it.

[Bob Smalser]

I should mention that I will be pouring directly into a cut out section of the plywood centerboard. I have the cutout, backrouted?, so the lead will be locked in place. I have heard that waterglass can be painted onto the wood to prevent scorching? Seeing as how I cannot heat the mold should it be poured at one go?


On a small pour like yours, chalk works adequately to protect the wood providing you practice cooling the lead by swirling the ladle to the minimum temperature at which it'll pour. The lead inside your pour will lose heat at a lesser rate, but you can play the torch on it to heat if required.

Here's how I do small pours...notice the backer board, level, thru-hole and dovetailed mortise, and tightening the lead after cooling:

http://www.woodenboat-ubb.com/vbulletin/upload/showthread.php?t=8948

http://pic3.picturetrail.com/VOL12/1104763/6583947/84771679.jpg

Above is an 80lb block of lead hanging off the end of the sawhorse I play the torch on with the warm ladle beneath.

As this pour is only 20lbs or so and done quickly, chalk or waterglass wasn't required to prevent scorching. I've done over 50lbs using the same method, only with chalk or waterglass to protect the wood, heating the puddle when necessary to prevent a cold joint.

Waterglass is available at foundry and some farm supply (poultry) stores. Pharmacies also carry it, I believe.....sodium silicate powder. My Grandmother preserved hen's eggs in the stuff. While schools don't use blackboards any more, toy stores carry sidewalk chalk in big chunks.

http://pic3.picturetrail.com/VOL12/1104763/6583947/84771686.jpg

[Tom M.]

On the small pour for my leeboard, I didn't pour at all. Instead, I bought some lead shot at the sporting goods store, in the fishing section I think. Then I sawed a hole clear through the board where I wanted to put the weight. I placed the 'board over waxed paper on a bench, mixed and poured a little epoxy, then lead shot, then a little more epoxy, until I filled the hole. Wait until the epoxy is almost too hard to plane, and then plane it. It worked great, and took no time at all. You can rout a key in the hole before you pour if you want, but I didn't. It hasn't fallen out yet.

[Bob Smalser]

... lead shot at the sporting goods store, in the fishing section I think. Then I sawed a hole clear through the board where I wanted to put the weight. I placed the 'board over waxed paper on a bench, mixed and poured a little epoxy, then lead shot, then a little more epoxy, until I filled the hole....

http://pic20.picturetrail.com/VOL12/1104763/3955069/50326170.jpg

Or you can simply thin the epoxy using a heat gun to have it saturate the lead.

Simple, but the graphite the shot is coated with doesn't make for a great bond, so fully encapsulate it in epoxy. Also doesn't provide as much weight for the size of your mortise as poured lead.

[Tom M.]

http://pic20.picturetrail.com/VOL12/1104763/3955069/50326170.jpg

Or you can simply thin the epoxy using a heat gun to have it saturate the lead.



Yup, good point. I stirred it all together with a stick to make the lead and epoxy one unit, and stuffed the hole with as much shot as it would take. The epoxy should just fill the holes between the shot, and no more.

What is that a pic of?

[Bob Smalser]

http://pic20.picturetrail.com/VOL12/1104763/3955069/50554506.jpg

I figured I was too close to two epoxy lamination joints to use hot lead.

[Tom M.]

Jeez Louize

You get an indoor shop Bob? Or is that the shed still?

[Bob Smalser]

Jeez Louize

You get an indoor shop Bob? Or is that the shed still?

Same setup. Building the house first, then the barn.

[Bill Childs]

I'm ashamed to admit it... but I had to look good on paper at one point in my life to buy a house. I quite building real boats and punched a clock at Nordic Tugs whittling teak staterooms inside of ungainly plastic tubs so the bank would think I had a real job - yeah. Depending upon how many refrigerators, generators, microwaves, and wet bars they installed, and where they placed them in the boat, they would pour between 300 and 1000 lbs of lead shot mixed with polyeter resin in the bilge just forward of the stern to make them float near the designed waterline. It was painful to watch. Almost as painful as listening to the Sperry Topsider and argyle sock wearing buyers of these ridiculous craft when they took a tour of the factory to see their future dreamboats being built.
"Darling, do you really think we should buy the boat this year or the condo in Hawaii?"

Sorry for the slight deviation in topic - a brutal memory gland was jarred loose with the mention of lead shot. Carry on.

[Bob Smalser]

I'm ashamed to admit it... but I had to look good on paper at one point in my life to buy a house.

I understand. I have a shameful amount of commercial experience with particle board, dowel and biscuit joints, corrugated nails, T-nuts and cheap laminates I never talk about.

[Greg Nolan]

When it gets to the point of 'boiling', it will then begin to emitt the dangerous vapors. I believe it is around 650 when this happens. If you melt it and keep it just hot enough to pour (without getting it too hot) you will avoid that added danger.

I recently poured a weight into a Mahogany rudder; no charring at all.

Dangerous vapor will be given off by any molten lead -- the amount of vapor will increase with the temperature of the lead, but the molten lead doesn't have to be "boiling" to be producing dangerous levels of toxic vapor.

[PeterSibley]

I would recommend coating the wood with Sodium Silicate, "water glass" to hold down the scorching. It's a shame they took the lead out of wine bottle foils. Us winos put 200 lbs. of foils into "Taliesen's"
keel when we poured it.

I have to disagree with you on this Jay,perhaps we did something differently but a week or so back I ran a little experiment to find the best thing to line a mould with .(I've got a big pour coming up).The sodium silicate wasn't good at all,the casting was all bubbly and rough.For a small pour I'd probably line the mold with something like our Hardiflex wall board.

For mine ,5600 pound ,I'll use a mix of kaolin and aluminium oxide or hydrate plus a bit of PVA glue to bind it .Its the stuff potters use to paint kiln shelves .

[Jay Greer]

And to think we've been wasting all that water glass over the years!
Even so, my drafting ducks turned out perfect. Our big pours go into molding sand.
JG

[davef]

I would do it in one pour. 65 lbs isn't that much and can be done safely. I poured 400lbs in one pour although I had an overhead gantry.

I went to the local salvage yard and found an old air compressor tank which I cut in half to use as the pot. I melted the lead over a charcoal fire inside a section of conduit. Perhaps some of these techniques would work for you.

[PeterSibley]

And to think we've been wasting all that water glass over the years!
Even so, my drafting ducks turned out perfect. Our big pours go into molding sand.
JG
Interesting Jay....my result definitely wasn't good.I wonder if there are different compositions of sodium silicate on the market .I use this particular one to make sand cores for casting .Some difference anyway.

[Jay Greer]

Peter,
I think I know what caused your problem. Water Glass contains "water of crystallization" So, if all of the water isn't driven off by thourough drying, steam will be the result when the pour is done. I would guess that is what caused your surface blems.
JG

[PeterSibley]

I'll run the test again Jay.The surface of the mould really bubbled,next time I'll leave it longer to lose its water, last time was overnight ....if I remember correctly.

[Ed Strong]

Thanks to all for the help on using lead in my centerboard. Made the pour today without problem. No apparent burning of the wood. Did use chalk on the wood.

[Ed Strong]

Thanks for all the help on using lead. I made the pour today without problem. Used chalk on the wood - no apparent burning.