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Re: Razor Blade and Glass



:Date: Tue, 10 Apr 2001 21:38:28 -0400
:From: "John T. Fitch" <JTFitch at FitchFamily_com>
:Subject: Razor Blade and Glass
<snip>
:because I've been doing just that for some time with a razor blade mounted
:on the end of a dowel rod.  I will suspend that method until others confirm
:or reject Gary's dictum.
:
:However, I did look at the Mohs scale of hardness to see if it shed any
:light on the subject.  Unfortunately, the various versions I found on the
:internet provided somewhat ambiguous answers.  Neither steel or glass is
one
:of the ten defining minerals that carry hardness numbers from 1 to 10.

Wow, talk about hitting a gnat with a sledge hammer.... a metallurgist!
I guess you didn't see Crouching Tiger, Hidden Dragon where she used her
sword to cut through stone :-)  I guess I'm not to keen on the consensus
theory either as I saw what it did for "clean water is blue" and "FFFF are
friendly, are not".  You figure out what the extra F is for :-)

I have no reason to blow smoke up your skirt and tell you that razor blade
algae cleaners can scratch glass.  I guess it means either that you've
cleaned less tanks than I have or that I've cleaned way too many tanks!
Ochem's razor would suggest the former :-)  I can tell you that I have
personally replaced a 10 gallon photo tank and a 20 gallon high photo tank
for precisely these reasons.  I was using one of those very thin, sharp,
double razor blades in an aquarium approved scraper.  Rub a little hard on
an algae spot, catch a corner of the blade and...you've got a scratch,
usually in the center of the tank where it's most obvious.  You might not
catch the corner so easily with a thicker, single blade version but I do
know of people who have scratched their glass while scraping w/o a holder.
And yes, Murphy's Law was in place and it occurred right in the center of
the tank.  Shoot a part of a tank (with a flash) that has a scratch, and
it's like George Sr's "Thousand Points of Light...".  I would hate to see
someone mess up a beautiful, expensive 90 gallon or bigger tank because of
the unwillingness to get their arms wet!  BTW Ivan Busko's comments about
the 3M pad, that's a different pad than the O-Celo pad as this pad is the
same on both sides.  It's yellow with whitish nylon on the outside and a
sponge is in the middle.  You can't scratch glass with this pad unless you
put gravel/grit in between it and the glass.  Put it on your grocery list
and then next week everyone can report how wonderful it is.  It's only US$1
so it won't break the the fishy bank account!

True gardeners will tell you that you have to get down on your hands and
knees and feel the earth... I'm just suggesting that you get into your water
gardening and feel the wetness, all the way up to your armpits.  Simplify
and get back in touch with your tank :-)  Just don't pull up any gravel in
your spongepad.

On a final note I've decided to try CO2 on that scratched 20 gallon tank to
see whether it will fix the scratches!  After all, glass is but a liquid and
we now know that if you have a problem, "turn up the CO2" VB :-)  I've gotta
frame Tom's "Car" analogy for regulating growing factors in our planted
tanks.  It's priceless and right on the mark!  Keep telling them, maybe
they'll listen.

Gary Lange
gwlange at mindspring_com



:As examples of material hardness, though, the majority indicated that glass
:was a bit *harder* than a knife blade (glass = 6-7, knife blade=5.5), which
:means the knife shouldn't scratch the glass.  One version, however, gave
the
:knife a hardness of 6 and glass 5, in which case the blade could scratch
the
:glass.
:
:Do we have a metallurgist in the group?
:
:John T. Fitch
:E-mail: JTFitch at FitchFamily_com
:Web Page: www.fitchfamily.com
: