[600MRG] restoring old crystals ??

Wed Feb 6 00:10:54 CST 2013

Ken the chemist in me won't leave that dangling.  Rubbing alcohol is
iso-propyl alcohol, a whole different specie than ethanol which you
are thinking of.  Iso-propyl is a decent cleaner but tends to leave a
light residue that you still need to get off.  The same thing happens
with the very aggressive acetone, it leaves a residue.  In the lab we
often dry glass after it is cleaned with ethanol, usually 95%, which
does have a denaturing chemical in it and some water. It is a good
solvent though and useful in cleaning and quickly dries clean if it is
reasonably clean alcohol to start with.  The water evaporates with the
alcohol.   The expensive stuff is 99%.  Generally you can get the 95%
ethanol at the hardware store, often beside the cheaper methanol and
acetone.  The methanol would work but it is too volatile, meaning it
evaporates too fast.   Methanol and ethanol are very flammable and
burn with an invisible flame, so be extra careful there not to burn
down the house.   Yes there is something in the 95% ethanol to make it
undrinkable, so do not try that. The others are undrinkable all by
themselves.   I would use the 95%.  You should not need the 99% which
is often called Gold Shield and is very expensive.
However, going back the iso-propyl, which is what the Doctors use to
sterilize and for other uses on the skin, such as to clean, I have
noticed a tendency for that to be more dilute today than it used to
be.   Most commonly it use to appear in the stores as 99%, then it
became difficult to find even 95% and then the strongest available was
91%, and last time I looked, 5 or so years ago the most common was 85%
which, of course brings down the volatility and the flammability a
little, but that one does not work as well for anything.  For example,
even 91% will not get rid of poison oak blisters.  When it was 99%,
that was the best remedy for it, just treated like a burn by blotting,
not rubbing.  95% works slower.  I think it is the water in the other
strengths that just makes the blisters get worse.
Anyway, you could use iso-propyl alcohol like you could get at the
pharmacy for your cleaning needs, which may be a higher percentage
than the iso-propyl you get at the hardware store (which you could
also use) for the major cleaning and then just rinse in the ethanol
afterwards.   Iso-propyl does not evaporate as fast as ethanol.  That
way you toss the dirty iso-propyl after it has cleaned the whatever,
toss in recycle, of course, and then put the mostly still clean
ethanol back in a DIFFERENT bottle, never the same bottle it came out
of for use for the same purpose later.
Anyway, as I said, I just could not let that stand the way it was
written, Ken, you have to know what kind of alcohol you mean. There
are many.  And, by the way, probably all of them are in gasoline to
some very small extent.   Once there were several groups of scientists
who thought methanol might make a good fuel to use in autos.  Not bad,
actually, if you redesign the engines and figure out how to handle the
corrosion that is present because the alcohol removes the oils.  In
Brazil at the time they used ethanol for the cars.  The idea left at
least some of them having nightmares about crashing automobiles that
catch fire (or catch fire without crashing) and other cars driving
through or into the fires because you cannot see the flame.   We had
similar nightmares about battery acid in electric cars spreading out
over the freeways and the bodies.  Well, at that time (1970 or so)
most of the electric cars just had tons of lead-acid batteries.
Bill
-- 
--------

William E. Isakson
Roseburg, Oregon USA
bill.isakson at gmail.com

“It is impossible to rightly govern a nation without God and the
Bible.” – George Washington

On Tue, Feb 5, 2013 at 4:33 PM, Kenneth G. Gordon
<kgordon2006 at frontier.com> wrote:
> On 5 Feb 2013 at 14:11, Merv Schweigert wrote:
>
>> Ken is correct on all counts,  I have activated many old xtals
>> by cleaning the blanks and careful reassembly, all that was
>> need was good alcohol bath,   not rubbing alcohol but the
>> potent stuff from the pharmacy usually.
>
> Right! Rubbing alcohol has been "denatured" by adding something like
> gasoline or worse to it. Use full-strength pharmacy-grade alcohol.
>
>>  Do not touch the xtal
>> after cleaning, use "tongs" or something hold the edges and
>> put it back in the clean case.   Have had almost all bad ones
>> come back to life.   You will change the freq if you use acid
>> or any other "grinding" method.  I assume you want them to
>> stay on freq.
>
> Yes. I thought so too. Isn't that true, Neil?
>
>> If grinding buffing compound mixed with water to a paste
>> works well,  comes in many grits,  a piece of flat plate
>> glass works as a bed.  the surface has to be perfectly flat
>> or the xtal is ruined as you grind.
>
> Yes. You should use as perfectly flat piece of heavy plate glass as you can
> obtain. It doesn't need to be much bigger than 6 inches square though.
>
> Having a glass "button", i.e. a circular piece of very thick plate glass to
> manipulate with your hand to use to hold the crystal down on the grinding
> "table" would be very valuable too.
>
> You grind in a figure eight pattern, manually turning the crystal 1/4 turn after
> every 5 or so "eights", then turning it completely over every complete
> revolution (every 4 5's).
>
> You have to do everything you possibly can to make certain the crystal sides
> STAY perfectly parallel.
>
> And you can only grind crystals UP in frequency, never down.
>
> Let's say you have done both sides for one complete revolution each: then
> you have to scrupulously clean the crystal, put it back into a clean holder,
> and test to see if 1) it is still active, and 2) how much you have moved it.
>
> Sometimes, if you have a calibrated receiver, you can lay the antenna very
> close to the crystal as you are grinding it, and "hear" the crystal chirping as it
> is ground. If you are careful, you can then follow its movement toward the
> frequency you want. But you have to stop well short, clean the crystal, and
> test as above to make sure you don't overshoot.
>
> Sometimes, if activity falls off, you can very carefully edge-grind all 4 edges
> and MAY bring it back....of course you could also ruin it too.
>
> At least we aren't still at the stage for making crystals shown in an old
> handbook: "First, buy a chunk of Brazilian quartz, as clean and inclusion free
> as possible. Then clamp it in a vice and begin vigrously cutting out a square
> with a hacksaw. A piece 1" X 1" X 1/4" will be suitable. This will take several
> days." Etc. Sounds like great fun, doesn't it? ;-)
>
> Ken W7EKB
>
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