Re: 19,008 LEDs on the wall, 19,008 LEDs

["Michael J. Mahon" <mjmahon@aol.com>]

Matthew Russotto wrote:
> In article <WtuBf.32$Xk3.111@news.oracle.com>,
> Martin Doherty  <martin.doherty@undisclosed.com> wrote:
>
> > logjam wrote:
> >
> >
> > > Just thought I'd give an update:
> > >
> > > -Of the 16oz of solder I started with only 7.25oz is left.  My food
> >
> > I know nothing about it, but I'm a bit worried about what noxious fumes 
> > you've been breathing while working on this project!
> >
> > Does anyone know whether excessive soldering poses a health risk?
>
>
> Well, typically solder contains lead*.  Some of that must become vapor
> and get inhaled when soldering.  And there can't be anything good for
> you in the flux either.

Conventional solder is a near-eutectic alloy of tin and lead (183 C),
and at typical soldering temperatures (~400 C), there is practically
no lead vapor released.  If you heat lead or lead alloy until it is
*much* hotter--approaching lead's boiling point (1749 C)--significant
vapor is released.

Rosin is the typical flux used in electronic soldering, and it
vaporizes at temperatures well below the melting point of solder.
The vapor is not particularly harmful, though many find it unpleasant--
like smoke.  The odor of rosin vapor has always reminded me of my
childhood, and building things.  ;-)  On the other hand, breathing
in a strong whiff of vapor is quite unpleasant, and you'll cough it
out quickly.

Then again, one of my hobbies was chemistry, and I found the odor
of many toxic (when concentrated) gasses interesting.  ;-)

The really dangerous gasses are the ones that can kill you without
bowling your nose over--carbon monoxide comes to mind.

A very effective technique is simply to breathe in while wiping the
soldering iron, then exhale slowly while soldering the joint(s).  This
esentially prevents any significant quantity of flux vapor from being
inhaled, since it is hot, and rises quickly above the level of your
head.

BTW, when you can *see* the smoke, it is no longer actually a
vapor, but a fine dust of now-frozen rosin particles, which will
contribute to the general dust level of your room.  ;-)

> *Yes, I know a lot of manufactured electronics are lead free nowadays.  All the
> solder I've seen for manual use on electronics still contains lead, though.

Tin-Silver-Copper (melting point 217-221C), Tin-Silver(melting point 
221C), and Tin-Copper(melting point 227 C) solders are becoming more 
readily available, but at a premium price.

-michael

Music synthesis for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

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