Scalebar
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lead into water - fine, pewter, not so
Something I experienced a long time ago but I caught something on a website that reminded me of it and set me puzzling.
As a kid I used to mess around melting lead and used to pour it into water to make odd shapes. As a 'grown up' ( yeh, right ) I've done the same with
silver to make convenient bits for remelting.
Try this with pewter - or quench a pewter mould a little too soon and you're picking bits of metal out of your forehead.
So what's the difference? Why no steam explosion with a metal that melts at 327C or a bit one with one that melts at 170C, is it something to do with
the leidenfrost effect?
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RogueRose
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Quote: Originally posted by Scalebar  | Something I experienced a long time ago but I caught something on a website that reminded me of it and set me puzzling.
As a kid I used to mess around melting lead and used to pour it into water to make odd shapes. As a 'grown up' ( yeh, right ) I've done the same with
silver to make convenient bits for remelting.
Try this with pewter - or quench a pewter mould a little too soon and you're picking bits of metal out of your forehead.
So what's the difference? Why no steam explosion with a metal that melts at 327C or a bit one with one that melts at 170C, is it something to do with
the leidenfrost effect? |
Density different, especially when hot?? was the temp of the water different when doing the pewter? Did you drop the pewter from less distance
(lighter weight, less distance = not breaking surface tension as quickly???) IDK, I'm just thinking possibilities..
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yobbo II
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It may have something to do the the Leidenfrost effect.
https://en.wikipedia.org/wiki/Leidenfrost_effect
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unionised
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If you put hot metal in a mould, the metal is trying to get in through the same hole that the steam is escaping from, and that's a problem.
If you just tip hot metal into water there's no problem with any steam that want to just bypassing the metal.
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Scalebar
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But if you pour pewter straight into water it goes quite emphatically Bang! and sprays everywhere, the same doesn't happen with silver or lead.
The heights would have all been about the same and the water just straight out of the cold tap.
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unionised
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Same depth of water?
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violet sin
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found this: https://www.youtube.com/watch?v=tj7S_DNFgEU
Pouring Molten Metals into Water.
it does show pewter popping at 0:53
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yobbo II
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The dude in the video mentions the Leidenfrost effect a few 10's of seconds into the video. The fact that the pieces will or will not ride down to
the bottom of the tank on an insulating layer of water vapour it a major reason why you get different effects.
Tryseeing the effect with a hot smooth bottomed saucepan on a cooker and drop some water into the hot saucepan. At 150C or so water droped into the
pan just sizzles. At around 250C the water runs around on the sauspan bottom like mercury for a considerable time.
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