On 26/01/2022 13:00, Peter Fairbrother wrote:
> - The only use I have come up with so far that needs >40% sulphuric is
> for making acid pirhana solution for cleaning glass and ceramics. The
> commercial 98% is undoubtedly useful for topping up baths for anodising,
> electroplating and electroforming, but it could be argued that 40% is
> sufficient here - not sure that is always true though, if you get in a
> mess sometimes 98% is the only thing which will do.
98%? Pooh! I would use oleum for making sulpho vanillin, a chemical used
for the identification of certain fungi.
When I was a yoof I could go into a chemist (not a pharmacist...) and
unless it was on the poisons tregister or some no-no like that, buy
anything over the counter, no questions asked. I often did too.
Now, the meddling killjoys have virtually removed from availability once
everyday compounds like potassium dichromate which I used to use for
artificially ageing some hardwoods.
"Why not use stain, sir?"
Because, you ignorant meddlesome control freak, when a wood like
mahogany or oak darkens with age, it's the harder, winter growth which
shows more oxidation, not the softer summer growth: a mirror-image of
staining, where the softer more porous open grain takes up stain more
readily. A dead give-away if you're restoring anything.
You can mix potassium dichromate with something combustible and it will
explode if you confine it and ignite it, but the expense! (When you can
cheaply buy huge bags of fertiliser you can detonate rather than
ignite...) Who the hell is going to bother with chromate, nitrate, &c?
--
Rusty Hinge
To err is human. To really foul things up requires a computer and the BOFH.