On Tue Jul 18, 2006 at 5:13 am (PDT), mycroft2152 wrote:
>The active ingredient in Brake fluid is a glycol, as per the MSDS
>(Material Safety Data Sheet):
Errm, not quite: add up the percentages in the MSDS.
It's 21% to 37% various glycols but the major part, 63% to 79%,
is various glycol ethers, not at all the same animal.
>http://www.warcopro.com/spanish/pages/brakefluid-pdf.html
Also note that this is a DOT3 specification, which is rather old.
AIUI, modern cars may be using DOT4 or better, which will have
a different formulation, probably to reduce its affinity for water
and increase its boiling point, thus reducing the risk of vapour-
lock under heavy braking.
>Glycols are used in may commercial products and even foods. Look for
>Propylene or ethylene glycol in the ingredient list.
Propylene glycol is GRAS in food - but isn't in this brake fluid.
Other glycols probably shouldn't appear in food, except for
polyethylene glycol (PEG), used as an anti-foaming agent in
Dr Pepper and with several uses in medicines.
Glycols are close relatives of alcohol and some have a sweet taste.
IIRC, diethylene glycol was used some years ago, quite illegally,
as an improver for Austrian wines.
However, if you again consult the MSDS, you will realize that you
probably wouldn't want to consume any of these glycols, since the
oral rat LD50 (50% mortality after consumption by mouth) is in the
range 22g per kg body weight (for PEG) down to 4.7g/kg - and the
glycol ether is, usually, more toxic than its glycol parent.
[However, for comparison, the oral rat LD50 of ethyl alcohol,
grain spirit, is only 7.06g/kg - but I would suggest that its
consumption would be much more fun, with better understood
ancillary health risks ;-) ]
>Antifreeze is another good source, but has other chemicals in it.
Probably diethylene glycol plus corrosion inhibitors and dye: cheap
antifreeze may contain alcohols but these make it corrosive
to aluminium and hence unsuitable for modern engines.
>Glyceerine is a close cousin and should aslo work.
Glycerine (glycerol, E422) is close to glycols but only a second cousin
to glycol ethers. It is often used as an humectant in products such as
chewy sweets and crumbly cakes to maintain their texture. It is so
hygroscopic that if you apply it to your PCB it will never be dry in an
atmospheric humidity comfortable for humans.
>[snip] Theoretically, you could add the glycol to the ink itself.
Except that:
a) glycol, per se, is not the major ingredient of the formula you cited
(and we don't know what brake fluid Volcan used), and
b) glycol is already an ingredient of many inkjet inks but possibly not
of the special inks we find usable for direct resist printing (I have
seen a suggestion that some of these may be acrylic - other ideas?)
c) and then only if we don't mind changing the ink's drop-forming
dynamics at the nozzle.
Regards, LenW