.this borax cone that everyone is talking about -- is this the
same thing as the white boric acid powder that I have mixed with
denatured alcohol and dip all my work into before I bring the torch
to it????
G’day; no it ain’t! The borax cone is just that; a cone made of
sodium diborate, borax. The stuff you dissolve in alcohol to coat
sterling before heating is boric acid and quite different - it isn’t
as good a flux as borax… You dip it in the alcohol solution so all
you need to do is to apply a flame and the alcohol will burn off with
a greenish flame leaving the boric acid on the workpiece. You can
repeat this many times if you wish, to build up a thicker coat. Prips
flux contains both and is quite a good flux as well as being a good
anti oxidant coating to avoid the dreaded fire stain. (copper oxide
from the sterling alloy; fine silver doesn’t do that) Incidentally,
don’t let the word ‘acid’ in ‘boric acid’ throw you; it is called an
acid by chemists because it contains an available hydrogen atom - but
it is one of the mildest acids you will find. I haven’t included
chemical formulae in this note because they only confuse the issue to
anyone not understanding them. Not all of us remember the bit of
chemistry we may have learnt at school. Unfortunately. Cheers, –
John Burgess; @John_Burgess2 of Mapua Nelson NZ
In Europe the standard dish for grinding borax IS a hard fired
porcelain dish and NOT a slate dish.
My original post seems to have vanished into thin air.
If you had ever been to a Chinese restaurant soy sauce and other
condiments are served in a small ceramic dish. These dishes have a
flat bottom with a high rim and therefore very suitable for grinding
and holding your borax cone mix. A rough measurement of my dishes are
of diameters 7cm(2.75 in) and 10 cm(4 in). They each cost only a few
tens of cents and are available from any Chinatown general store.
Kelvin Mok @Kelvin_Mok1
Hi Kevin,
You can use any size you like there is no harden fast rule. Most of
the dishes purchased in the UK and New Zealand tend to be about 4 to 5
inches in diameter with about a half inch rim. Although I have a
feeling we just bought one made of Marble which is smaller. All the
dishes I have used are high fired clay ( I made one myself many years
ago which was only biscuit fired. It worked fine for grinding the
borax but the water gradually seeped through making a mess of my solid
Rimu (native NZ timber) bench. If your dishes are glazed they might
not work unless you rough the surface up somehow. If they are not
glazed I am sure they will work. I have used slate and glass aswell
but I prefer my dish. If your dishes are that cheap why don’t you just
give it a go, if it is no good use it for soya sauce. After you have
cleaned it of course.
Chris Hackett