Sandy wrote:

Disagree. One can observe a cause and effect repeatedly and draw valid
conclusions without understanding the mechanism.

Disagree. If you don't understand the mechanism, or the rationale, you
are very likely to cock it up when things don't go exactly as
expected. Especially with complex procedures.

LOL! Do you really think that the inorganic chemistry involved in the
derusting process is more complex than the operation of the
gravitational force and the organic chemistry and electrical processes
involved in the sensing, transmittal, and interpretation of the pain
signal?

Understanding theory does help immensely, when deviating from
experience, but empirical evidence can be adequate for some instances,
such as derusting some particular steel. Where I see theoretical
knowledge of the mechanism helping is knowing how it might work on a
different alloy, how different solutions might work if the known one
is not available, predicting long-term effects if evidence is not
available, etc.

Folks knew that
dropping a stone on their foot would hurt long before Newton and an
understanding of the nervous system (and do we yet fully understand
the mechanism of gravity, or just have more sophisticated observations
about it?) Charlie's point is valid; all we NEED to know is whether it
works.

And does it?
I'd like to know.

Charlie will likely never be quite sure.
Someone has to figure out how it works to be able to do it
competently.
No, I can quite competently grill a steak without understanding the
physical and chemical changes taking place in the steak when it is
heated. And a steak is, I would suggest, a far more complex object
than a piece of rusted steel, and the processes involved are also more
complex.

Not much is likely to go wrong with your strange hobby of
dropping rocks on your foot, I would have thought. Now chemical
procedures...
I'm sure you think they are more complex than the elemental forces of
physics or biological systems. We might just have to agree to disagree
on that! g

I'm with you in fascination with understanding why it works,
but that understanding is a want more than a need.

Again I disagree. So many things can go wrong with things chemical. So
many things waiting to bite you on the ass. DAMHIKT.
Yep. Sometimes I overcook a steak, and wonder if a more thorough
knowledge of the chemical changes going on in it might have kept me
from getting a medium-well steak when I wanted it medium.

I, like most woodwrkers,
am not a chemist.

Are woodworkers prevented from being chemists?

Reread the sentence you quoted.

Yes, and what point is it trying to make? Charlie is not a chemist, so
woodworkers don't need to know any chemistry?
No. That he is not a chemist, and that most woodworkers are not
chemists, and are probably more interested in whether it works than
how it works.
Do you disagree? Do you really think that most woodworkers ARE
chemists?


If they were mine, and I valued them, I would not use salt and vinegar
on them. This comes from my understanding of chemistry.

Why? What are the bad effects predicted by your understanding of
chemistry, and do they prove out in practice?

Yep. Salt will enter the fine pits and interstices of the corroded
surface and perpetuate future corrosion. Very difficult to clean
thoroughly.
That's good for part 1 of my question. And I believe I saw in another
post that you were going to do an experiment to find out part 2? I'll
be interested in hearing your results.

There was a guy once who ignored chemistry and
shot-blasted his aluminium boat with copper shot. It lasted but a few
weeks. Chemistry is VERY important!
Absolutely! And this is an excellent example where theory is important
to predicting the result of an untried process.


--
Alex
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