On Wednesday, June 1, 2005 at 5:48:12 AM UTC-5, rek...@gmail.com wrote:

The surface tension of liquid gallium is absolutely enormous;
V Kolevzon, G Gerbeth - Journal of Physics D, Applied Physics, 1996
and the CRC handbook suggest that it's something on the order of 700 dyn/cm, even more than mercury.

By that argument the liquid gallium should be sitting in a lovely
shiny sphere, scarcely touching the underlying material and definitely
not sticking to it, almost regardless of the material.

The laws of physics should still hold here - pure mercury acts
appropriately for its surface tension. Virtually the only thing that
keeps it from having a 180 degree angle with a surface is its huge
density, so you have the classic balance between between surface
tension force and gravitational force. My first thought is that there
is some kind of surface contamination going on. In the paper you
cited, even this careful study came up with an "anomalously" low
surface tension for gallium, in the range of 700 instead of 900 dyn/cm,
which they attributed to a surface metal oxide or organic film.
Surface tension is an incredibly local event and can be completely
altered by the presence of a monolayer of a different material. http://www.ubka.uni-karlsruhe.de/cgi-bin/psview?document=2002/chemie/8&search=%2f2002%2fchemie%2f8&format=1&page=40
This website actually talks about the difficulty of getting _pure_
gallium to WET a surface! They have to go so far as to glow discharge
a molybdenum (high energy) surface just to get pure gallium to wet it.
So I think I've convinced myself anyway that it's surface contamination
that causes the anomalous wetting. Gallium is so high energy that it
collects everything around it and forms a film on its surface that
causes it to wet. So again, going to an oriented -CH3 terminated film
or -(CF2)nCF3 film should work! (lower surface tension than the
probable organic contaminants)

what

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On Tuesday, November 3, 2020 at 4:19:29 PM UTC-6, Blake Brigance wrote:

On Wednesday, June 1, 2005 at 5:48:12 AM UTC-5, rek...@gmail.com wrote:

The surface tension of liquid gallium is absolutely enormous;
V Kolevzon, G Gerbeth - Journal of Physics D, Applied Physics, 1996
and the CRC handbook suggest that it's something on the order of 700 dyn/cm, even more than mercury.

By that argument the liquid gallium should be sitting in a lovely
shiny sphere, scarcely touching the underlying material and definitely not sticking to it, almost regardless of the material.

The laws of physics should still hold here - pure mercury acts appropriately for its surface tension. Virtually the only thing that
keeps it from having a 180 degree angle with a surface is its huge
density, so you have the classic balance between between surface
tension force and gravitational force. My first thought is that there
is some kind of surface contamination going on. In the paper you
cited, even this careful study came up with an "anomalously" low
surface tension for gallium, in the range of 700 instead of 900 dyn/cm, which they attributed to a surface metal oxide or organic film.
Surface tension is an incredibly local event and can be completely
altered by the presence of a monolayer of a different material. http://www.ubka.uni-karlsruhe.de/cgi-bin/psview?document=2002/chemie/8&search=%2f2002%2fchemie%2f8&format=1&page=40
This website actually talks about the difficulty of getting _pure_
gallium to WET a surface! They have to go so far as to glow discharge
a molybdenum (high energy) surface just to get pure gallium to wet it.
So I think I've convinced myself anyway that it's surface contamination that causes the anomalous wetting. Gallium is so high energy that it collects everything around it and forms a film on its surface that
causes it to wet. So again, going to an oriented -CH3 terminated film
or -(CF2)nCF3 film should work! (lower surface tension than the
probable organic contaminants)

what

say I put Teflon spray on a paper plate would liquid gallium stick to it

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On Tuesday, November 3, 2020 at 5:20:57 PM UTC-5, Blake Brigance wrote:

On Tuesday, November 3, 2020 at 4:19:29 PM UTC-6, Blake Brigance wrote:

On Wednesday, June 1, 2005 at 5:48:12 AM UTC-5, rek...@gmail.com wrote:

The surface tension of liquid gallium is absolutely enormous;
V Kolevzon, G Gerbeth - Journal of Physics D, Applied Physics, 1996
and the CRC handbook suggest that it's something on the order of 700 dyn/cm, even more than mercury.

By that argument the liquid gallium should be sitting in a lovely
shiny sphere, scarcely touching the underlying material and definitely not sticking to it, almost regardless of the material.

The laws of physics should still hold here - pure mercury acts appropriately for its surface tension. Virtually the only thing that keeps it from having a 180 degree angle with a surface is its huge density, so you have the classic balance between between surface
tension force and gravitational force. My first thought is that there
is some kind of surface contamination going on. In the paper you
cited, even this careful study came up with an "anomalously" low
surface tension for gallium, in the range of 700 instead of 900 dyn/cm, which they attributed to a surface metal oxide or organic film.
Surface tension is an incredibly local event and can be completely altered by the presence of a monolayer of a different material. http://www.ubka.uni-karlsruhe.de/cgi-bin/psview?document=2002/chemie/8&search=%2f2002%2fchemie%2f8&format=1&page=40
This website actually talks about the difficulty of getting _pure_ gallium to WET a surface! They have to go so far as to glow discharge
a molybdenum (high energy) surface just to get pure gallium to wet it.
So I think I've convinced myself anyway that it's surface contamination that causes the anomalous wetting. Gallium is so high energy that it collects everything around it and forms a film on its surface that
causes it to wet. So again, going to an oriented -CH3 terminated film
or -(CF2)nCF3 film should work! (lower surface tension than the
probable organic contaminants)

what

say I put Teflon spray on a paper plate would liquid gallium stick to it

After 15 years, I doubt it matters now ;)

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On 10/12/2023 00:16, Ethan Humphrey wrote:

What about Galinstan? Would a teflon coated steel muffin tin work to make it with a small propane torch?

I wouldn't use teflon with a torch; when teflon gets hot (above ~260 C)
it gives off really nasty gasses. As tin melts at 232 C you will almost certainly exceed the maximum temperature tolerance of teflon when making galinstan, especially with a torch.

Also, tin fumes will make you ill. Probably indium fumes too. I'd want
better temperature control than a gas torch can provide, but ymmv.
Probably won't kill you though, unlike overheated teflon which might.


Never made galinstan, but I use an electric solder pot for making and
melting similar gallium-containing solders, it's very heavily anodised aluminium. Probably shouldn't do that, as gallium and aluminium don't
mix (or rather they do mix, far too well).

Been in use for a couple of years now, but I don't recommend it. Been
meaning to get an inert liner for it since I got it, just never got
around to it.


You could use a silica or alumina crucible. Not very expensive,
especially considering indium and gallium are expensive anyway. I'd
avoid graphite.

Glass or pottery is probably ok for short-term use only.

But please, not teflon.


Peter Fairbrother

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