The lead sponge mystery continues....

Here is the best I could do to answer your questions. I posted it to the public video earlier. 1.) Why does the acid treated pre-dried sponge have such a low melting point? It appears to melt even easier than elemental lead. Lead Melting Point: 327.46 °C (​621.43 °F) Lead (II) Oxide Melting Point: 888 °C (1,630 °F) Lead Dioxide Melting Point: 290 °C (554 °F)

Matthew Wilson

I will move here the comments from my previous version of the video, which was hidden when the new one was uploaded: You have likely created a lead-zinc-air battery. The fresh sponge likely creates tiny electric currents as the zinc oxidizes throughout the mass. Also the zinc compounds in the non-acid treated sponge possibly act as catalysts to promote the burning of the metals when heated instead of just melting. Many years ago I managed to make regular electrical solder burn instead of melt when heated with a flame - this happened when I suspended small pieces of it in a small cage made of fine copper wire and heated it. I think the copper acted as a catalyst there too and let the tin and lead oxidize in the flame instead of melting. it was quite beautiful. The pieces of solder bloomed like flowers with strands of oxides growing in several directions at once. A little bit like the aluminum oxide grows in the mercury/aluminum experiment. my memory is not so good about the experiment as it was about 30 years ago. I think it was a short length of regular 63/37 rosin-core solder, perhaps 1cm long, bent in a u-shape. I used strands from a length of litz wire (I think 26gauge or thinner, with standard enamel insulation) to make a loosely weaved platform for the solder to sit on. The ends of the litz strands were bent upwards and twisted above, then a heavier wire formed as a hook used to suspend the whole thing in the air. I heated it from below with a standard cigarette lighter as I didn't have anything as fancy as a propane torch. The flame is quite reducing and it mustn't touch the assembly or else oxidation won't happen. You have to play with the distance between the tip of the flame and the solder to have the process start, then it's self sustaining. I repeated the experiment a few times and it worked every time. I haven't tried it again since though. Also IIRC it didn't work too well with longer pieces of solder. The smaller the piece the better the result.

Silviu T

Very interesting! thanks for the follow-up video

I wish i could have, but i dont own that thermal gun. I was just borrowing it at the time

Nile Red

oh, interesting!

Nile Red

Really should have used your thermal camera when filming the lead sponge after vacuum drying

Zinc oxidizes readily in the presence of heat. If you had a mixture of zinc, lead, and a little residual water, I would guess that it would behave exactly as what you got at the 15 minute mark: Bright flame, white smoke, steam explosions, and absolutely nothing bonding. I found I got very similar behavior when attempting to braze galvanized steel, no matter how much flux I would use. I solve the issue by dipping the steel in HCl to remove the zinc.

Paul Grodt

Interesting. Ill try to test it if i get the chance

Nile Red

oh no, weird. I will fix that!

Nile Red

Interesting. Do you know why it looked a little blue as well?

Nile Red

Have you tried reacting zinc powder with just acetic acid then treat the product with air, oven, or vacuum as a negative control for lead's influence? Then treat the product the same way you did such as HCl and/or torch. Also try torching fresh zinc and lead metal separately or combined, maybe they will melt forming a lower melting point alloy? Maybe they will light on fire as they oxidized? The softness is only present right after you take the sponge out I think is from the hollowness of the sponge filled with solution. Once you dried it some remaining salt inside the sponge probably crystalized or the structure stabilized like how clay settles making it brittle. Putting the dried sponge back in water does not make it soft again since the lead sponge material does not "absorbs" water like a regular sponge would. In a regular sponge, water molecules are attracted to cellulose or plastic polymers that retain their network structure even after drying. As for the sponge lighting on fire, I think the freshly prepared sponge just contained a lot more finely dispersed zinc powder and it just light on fire when you torch it.

I'm not in your supporter list :(

Bryan Boettcher

Gosh, please be careful! Guess there's no MSDS for Lead sponge.

Cool looking lead-zinc metal at the end Red Nile!

Daniel Blake Shoemaker

Interesting a Zinc-lead alloy. You cannot use your toaster again LOL! Love the orange (Yellow-orange color) Lead oxides when heated with propane and MAPP gas.

Daniel Blake Shoemaker

Interesting video! 10:25 that’s a really deep spoon or some great editing haha 😆. I had to go back to be sure what I saw.

The Gayest Person on Patreon

Hi and thanks for an interesting video. Your experiment reminds me of a test I did for a time ago. I sometimes get metal copper from my work, which I sell as scrap. If it is not clean, you get a very bad price, and many people are looking for a method of removing the tin that the copper is coated with. I have tried with hydrochloric acid, but it use so much and it reacts with the copper and creates a lot of copper chloride that stain down everything it comes into contact with. I tried electrolysis instead. A bath of 3% hydrochloric acid is prepared. Anode to tinned copper, cathode to clean tin metal. Electrolysis with about 5 Volt and 2 Amps, after about 5 minutes, the tin is dissolved. Rinse and wipe off with iron wool. The copper should now be completely copper-clean. Some questions about the process. What is that formed? Insoluble Copper (II) oxide that drains the liquid. Soluble Tin (II) chloride which should be oxidized to Sn (OH) Cl once all hydrochloric acid has disappeared. Strange enough stopped the process and no gases were formed, instead a gray mud floating on the water. When added more hydrochloric acid, this substance was dissolved and the electrolysis re-started. In my attempt to dry the liquid to see any salt, large amounts of HCl were released, which was very unpleasant when it was so much and strong. Nor could any salt be detected, except from the insoluble mud! The test reminds a lot of what you do. Which makes me think the copper is not at all coated with tin, but maybe lead. How can I know? Why did I constantly needed increase the amount of hydrochloric acid? In theory, this is a great method of cleaning scrap copper but I do not have the chemical education to make it perfect ... What do you think?

Emil Almberg

the acid treated lead had a lot of lead chloride which vaporizes pretty easily and formed the white on the pan.

CodyDon Reeder

If you make some zinc acetate and torch it, how does it melt? How does lead acetate react to the torch? How does a mixture of zinc acetate and lead acetate behave when torched? What if the chlorides are also present? Do they form a glass-like substance like the sponges did?

Definitely fascinating; great video!

Michael Aichlmayr