rockyit98 - 27-6-2021 at 08:24
did you know some hydrated borax foam like crazy when heated. i found it the hard way while trying to melt copper for the first time. added 150g of
copper and little borax that I got from long time ago in to a small crucible and heated with charcoal. a minute later most of copper pcs was out of
the crucible and it's space got filed up with some white stuff . I seen people melting borax on YT but never that. the problem seems to be it's
sodium tetraborate decahydrate (Na2B4O7ยท10H2O) which is 47% water that's boil and makes pores so it end looking up like polystyrene foam and really
light weight like so . a link to a picture from a fella that in the same boat as me https://www.iforgeiron.com/topic/66211-unexpected-result-bor...
I think if you left out in the air, it will dissolve or crumble with absorbed water.
Fulmen - 27-6-2021 at 11:10
Interesting. Sounds like the basis for a fire retarder.
S.C. Wack - 27-6-2021 at 12:48
It runs away from fire. If one heats it at the bottom of a crucible, the bottom will soon have no borax in it. It also absorbs CO2 like any other
alkali.
draculic acid69 - 28-6-2021 at 02:28
How could borax absorb CO2?
njl - 28-6-2021 at 02:35
Maybe forming NaHCO3 and boric acid?
S.C. Wack - 28-6-2021 at 14:25
Carbonic acid. Perhaps dry CO2 would have no effect. What about borax from the mine, one might ask. The ore is dissolved and boiled; the boiling
releases CO2.
Older, more descriptive versions of A Dictionary of Chemistry (Watts) mention that both the penta and decahydrate swell, the deca moreso. It does have
an interesting texture.
Apparently the people responsible for regulating consumer use of borax in Canada and the EU have found new jobs lately in their natural home of
Florida, coordinating a dozen people standing around holding blue buckets.
macckone - 28-6-2021 at 15:22
Borax often contains sodium carbonate and water.
I have never heard of it containing sodium bicarbonate as a normal impurity but I can see it being added for 'washing'.
Borax is used in flux welding. If it isn't dry it foams like crazy.
The picture in the forging post is prepping it for welding and it got too hot to quick.
unionised - 29-6-2021 at 06:05
If you heat borax, it foams.
It always did.
I'm not sure why this is being labeled as "unexpected".
If you continue to heat the "foam", it melts an you get the borax glass that's used for the borax bead test.
Boric acid is, just about, strong enough to displace CO2 from carbonates, so I'd expect the reverse reaction to be slow to non existent.
However, the dry material will pick up moisture from the air