Brian,
I am truly impressed by your technical acumen curiosity.
It reminded me of the brief study Richard Feynman did during the Rogers Commission which investigated the Challenger Disaster. I had the flu and was watching the commission on C-SPAN when Feynman dropped a material sample of the O-Ring into a pitcher of cold water to prove how brittle it was.
Well Done.
Lee Whiteman, PMP
Senior Member Engineering Staff
L-3 Communications East
Telephone: (856) 338-3508
FAX: (856) 338-2906
E-Mail: [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Saturday, June 20, 2009 3:34 AM
To: [log in to unmask]
Subject: Re: [TN] Hand Sanitizers Round 2
Doug
1. Have a look at pp116/7 of a certain book which I imagine
Rockwell-Collins probably has somewhere.
2. As you may be aware, I recently had a 3-week visit to a hospital. For
one week, I was in a cardiac ICU, where most of the patients were
bed-bound with coronary problems. My problem was purely
electro-mechanical and I was unhooked from the monitors during the day
after three days and was able to move around. As the Unit was
constructed for bed-bound patients, it had sanitary facilities only for
the doctors and nurses, so I used them. Other than the usual things, I
found two squirt-bottles of two different hand sanitisers. As this was
not long after the previous thread on the subject, I had a look at the
composition. Both contained weakly ionic salts and surfactants, although
the major components were light alcohols and water. As my experimental
facilities were limited in such a 'laboratory', I was unable to do
electrical tests, but curiosity got the better of me. I very carefully
washed, with ordinary soap, and rinsed my hands in the hottest water I
could bear and dried them on a paper towel. After a few minutes cooling
off, I thumb-printed onto the corner of the mirror with little deposit,
although careful examination showed some paper lint from the towel. I
then put on one squirt of hand sanitiser and massaged it well in for a
minute or so, until the hand was apparently dry. I waited a few minutes
and thumb-printed on another corner of the mirror. The print was quite
visible, indicating that non- or low-volatile components remained on the
fingers. I went back a few hours later for a call of nature and the
print was still visible, although slightly attenuated. I took the
opportunity to repeat the experiment with the other product, which was
less 'smooth' and the results were similar. In fact, the two sanitised
thumbprints were still visible the following day (so much for the
cleaning staff!!!!) but had been cleaned off the day after that.
I concluded that a) there were non-volatile components, probably a
cocktail of hygroscopic surfactants (PEG and sodium lauryl sulfate) and
organic weakly-ionisable salts (sodium lauryl sulfate and potassium
laneate) left on the fingers b) there may be a risk handling sensitive
electronics with fingers contaminated with such substance, even the bare
boards, if there is no subsequent water wash c) I was not over-worried
about the fragrances as, by definition, they are volatile. My nasal
chromatograph/spectrometer could not detect their presence after 10
minutes and they were at the end of the list of ingredients so would be
in much smaller quantity than the others (neither product contained
colorants).
I cannot pretend that these two products represent every hand sanitiser
on the market, but such experiments are easily repeated. My gut reaction
is that only Marseilles soap bars (sodium oleate without additives, no
detergents) with a good rinse protocol should be allowed and that
operators should wash their hands before starting work and after every
break. Obviously, gloves are an alternative, but not necessarily better.
Equally obviously, these extreme measures are applicable only un the
minority cases where the end-product justifies them.
Hope this helps.
Brian
Douglas Pauls wrote:
> Good afternoon all. I hesitate to ask this on a Friday afternoon, but
> here goes.
>
> Back in April, we had a Technet conversation about hand sanitizers and
> possible effects on electronic assemblies. I just re-read the thread from
> the archives. There was a lot of speculation about the effectiveness of
> these items from a bacteriological perspective, some about the chemicals
> from Karen Tellefsen, but nothing really related specifically to known
> failure mechanisms of these materials or studies that have been done.
>
> I was not as concerned about this until I started looking harder in our
> facility. I have found that there are several hand sanitizers here with
> dyes and fragrances. Germ-X makes a green hand sanitizer with apple
> fragrance, called Gnarly Green Apple. I would love to spec that material
> in here purely for the reason that it would be the first known use of
> "gnarly" in a Rockwell spec. I wonder if the dyes are an issue or the
> fragrances (usually oils).
>
> I was just in a meeting discussing this with a number of leaders in
> various manufacturing areas. We also have concerns about hand lotions
> coming into the facilities in ladies purses and being used because they
> don't like the smell of the approved ones we have from Chemtronics or
> Techspray.
>
> We have the big safety net in our facility of a saponified aqueous water
> wash process just prior to conformal coating, and everything handled with
> gloves thereafter, but the intermediate steps where we might have
> solderability issues or residues that might cause a high voltage power
> supply to fail in ICT, have me wondering.
>
> So, I ask the question if anyone in the Technet community knows of any
> scientific study examining the transfer of hand sanitizer chemicals, or
> hand lotion chemicals, to an electronic assembly and / or the detrimental
> effects of such residues. I can't believe that I am the first to ask the
> question and am wondering if someone else has already done an analysis so
> I don't have to re-invent the wheel.
>
> Doug Pauls
> Rockwell Collins
>
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