Roger
I'm glad my hunch was right. I won't use acid!
By the way Roger, there is a big sandstone quarry near you at:
Contact Windmill Sandstone Quarry. They have a good website and lots of
sandstone, but no Picture Rock.
Mail:
5 S Enterprises Ltd.
P. O. Box 130
Cowley, AB
T0K 0P0
Telephone:
(403) 628-3912
Fax:
(403) 628-2221
Cellular Tel:
(403) 627-8558
Location:
Windmill Quarry is located in Southern Alberta, Canada.
The quarry is situated
about 1.5 km West/southwest of Cowley off Highway # 3 .
Cowley is a town on
Highway 3 a few km west of Pincher Creek, or about 1 hr
drive West of
Lethbridge.
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John
John L. Carmichael Jr.
Sundial Sculptures
925 E. Foothills Dr.
Tucson Arizona 85718
USA
Tel: 520-696-1709
Email: [EMAIL PROTECTED]
Website: <http://www.sundialsculptures.com>
----- Original Message -----
From: "Roger Bailey" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, October 30, 2002 10:25 AM
Subject: RE: Eroded rock
> Hi John and all,
>
> Be careful here. The chemistry is specific to the rock. Edley describes
> experiments with "vitreous ceramics", specifically alumina. Corning Ware
is
> made from this tough stuff. I believe your rock is sandstone, a
sedimentary
> rock. Although this is mostly silica sand grains which are impervious to
> acids, the sand grains are cemented together in a matrix. The cement may
be
> silica and the rock a quartzite, on more likely it is a carbonate,
> limestone, dolomite or iron carbonate. These carbonates are decomposed by
> acids. If this happens, the cement between the grains is destroyed and you
> get rapid erosion. Limestone, marble, sandstone, slate, granite and the
> serpentine "Picture Rock" from Midway British Columbia are all different
> chemically. These are listed in order of reactivity to acid attack, first
on
> the list are attacked by acids, the latter are not.
>
> By the way the information that Patrick Powers provided on "Picture Rock"
> was precise but not accurate. Right name but wrong quarry. The "Picture
> Rock" from Midway BC is an igneous rock, serpentine with quartz veins.
Gold
> prospectors were looking for the mother lode in these epithermal
chalcedonic
> quartz veins. I believe your rock is sedimentary, a sandstone with iron
> (hematite) staining and veins from an Arizona quarry.
>
> Roger Bailey
> Walking Shadow Designs
> N 51 W 115
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Behalf Of John Carmichael
> Sent: October 30, 2002 7:29 AM
> To: [email protected]
> Subject: Re: Eroded rock
>
>
> Sandstone dust has a very salty taste.
>
> Does that mean I should dip my stone blanks in acid before I engrave them
to
> protect them from further erosion? A scary thought!
>
> When stone masons lay flagstone flooring, they often clean the unwanted
> calcium carbonate deposits off the stone using dilute sulfuric acid and a
> scrub brush. But I have always been afraid to use H2SO4 on my stones,
> fearing that it might damage the stone internally or cause the sedimentary
> stone layers to separate. I worry that this possible damage might take
> years to show itself. (But I observed no immediate damage to the stone
when
> I experimented with H2SO4, and it did do a very good job of cleaning the
> stone.)
>
> So you also have to be a chemist to make sundials, huh?
>
> John
>
> John L. Carmichael Jr.
> Sundial Sculptures
> 925 E. Foothills Dr.
> Tucson Arizona 85718
> USA
>
> Tel: 520-696-1709
> Email: [EMAIL PROTECTED]
> Website: <http://www.sundialsculptures.com>
> ----- Original Message -----
> From: "Edley McKnight" <[EMAIL PROTECTED]>
> To: <[email protected]>
> Sent: Tuesday, October 29, 2002 5:34 PM
> Subject: Re: Eroded rock
>
>
> > Hi Dialists,
> >
> > Awhile back, researching machining on vitreous ceramics, I came upon the
> statement
> > that most rock/ceramic surfaces have a much lowered surface strength
when
> the
> > surface was alkaline and a much greater strength when acidic. (It was
in
> a NASA
> > report, but I don't remember the number ) Experiments showed that indeed
> drilling
> > speed was up to 7 times faster on alumina ceramics while in a solution
of
> a mild
> > base such as borax than on a neutral surface. A mild acidic solution
such
> as boric
> > acid doubled the time of drilling. Shear testing and microcrack
> examination showed
> > that the acid surface actually was both stronger and healed many
> microcracks. Even
> > mild acetic acid made a great degree of difference.
> > Shaping with sand-blasting obeyed a simular effect. i.e. The surface
> chemistry of
> > the etched lines and their surrounds may be acidic enough to hold up to
> erosion
> > longer.
> >
> > Just a thought.
> >
> > Edley McKnight
> >
> > -
> >
>
>
> -
>
>
> -
>
-
