Homebrew PCBs

On Tue, 18 Apr 2006 at 02:46, Steve wrote:
>Subject: Re: Epson Cleaning
>
>http://www.polyphoto.com/tutorials/PrintHeadCleaning/
>
>1 part household non-sudsing ammonia (no lemon cr@p)
>4 parts 50% isopropyl alcohol
>5 parts distilled or filtered water (-not- purified water)

On Tue, 18 Apr 2006 at 15:31, Steve clarified:

>...You can
>skip the IPA if you wish, but you should use filtered or distilled water.
>
>"Purified" water is just tap water that has had clorine gas added or
>been passed under UV to kill junk in it, but still has all the minerals.
>
>Steve Greenfield

This seems to be another example of  GBS's aphorism
"Two nations separated by a common tongue."

This morning my father bought from the local chemist (pharmacy)
"Purified Water (Conductivity under 30uS) Non-Sterile 5 litre" @ £2.79

[We also have "Purified Water BP" which comes weld-sealed in
poly bottles and is sterile and guaranteed to be free of pyrogens too
but I don't know the specification of that offhand.]

Now, 30uS (microsiemens per centimetre) sounds pretty pure to me.

True, it's not as low as pure water (0.055uS/cm @ 25 deg. C) but
it's better than rainwater (35 - 100uS/cm) which is normally considered
relatively free of minerals, i.e. ionic compounds.

I strongly doubt the water for the household ammonia is much purer.

30uS/cm approximates to 15ppm NaCl or 20ppm mixed salts.
Surely not enough to compromise print heads?


Regards, LenW
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