Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Hi

I know i am telling you something you already know but please be aware that
HCl is very corrosive.
i forgot a small char of hcl plus h2o2 on my workbench, it made a set of
hss drill bits rusty in two days.
when i discovered it the jar was almost dried out. the rust wasn't too
serious, i didn't think it would be a problem.
when drilling it would simply diasppear (if you rubbed it with your finger
it disapeared without traces.

so i removed the etchant char and thought everything is alright.
today (~three days after removing the jar) i discovered the drill bits have
rusted MUCH MORE.
there was already some rust falling down from them in the case where they
are stored (this was open all the time).

i decided to put them in a jar with NaOH in water. then i dried them with
paper and brushed of the rust with a steelwire brush.
finally i oiled them with thin oil (they were almost new and most had the
factory oil still on them - it didn't prevent rusting.

only a 4mm banana plug is another victim of the acid so nothing serious is
damaged.
but the cleaning of the drills took some time and i fear now they may be
less precise because the shafts
were corroded only at one side. there were expensive good drills and i
think i will never forget the etchant char again......



so please be cautious


regards
stefan

note:
i store the etchant in a 1 liter glass bottle.
it has a plastic cap with a 1mm hole punched through.
the hole is covered on the outer side by a 1cm wide and 2cm high plastic
"cap". the cap is filled with some flexible foam and is open at the top.
this forms a "overpressure valve with anti-spill if the bottle accidentally
falls on one side".

i always kept this bottle amongst some toos and it never caused any
corrosion.
so this small opening and maybe the foam prevents too much acid getting
into the air.