William,
Well done and well said!
Scott
-----Original Message-----
From: William Spurlock [mailto:wspurlock@savinggraves.com]
Sent: Sunday, September 30, 2001 8:59 PM
To: INPCRP-L(a)rootsweb.com
Subject: Re: [INPCRP] Chalk
The issue of the use of chalk to bring out lettering on a stone can be a
touchy one, sometimes just as much as the use of shaving cream. And just
like shaving cream, there is a lot of just plain wrong information on the
internet and in other resources. So before I said anything one way or the
other, I did some research on the question to find out what true experts on
the subject had to say, and followed up with some experiments to confirm.
I figured that the best place to start was by contacting Crayola and asking
them if they felt that the use of chalk on stones was safe for the stone
itslef. Here's what they had to say:
"Crayola sidewalk chalk contains plaster of paris which has a gritty
texture. Plaster of paris is not considered to be biodegradable, nor are
most of the pigments contained in Crayola sidewalk chalk. Also, product
packaging warns of colorants that may stain. This could be a good factor
depending on the exact nature of what you are trying to do. While packaging
does warn of colorants that may stain, chalk used outside generally washes
away because of extreme weather conditions and excessive rain. Again, this
could vary depending on the surface it is applied to."
If you look on their website, you can find the following additional
information:
"Molded chalk, such as Crayola Colored chalk, is a softer chalk, made of
plaster of Paris, which is defined as quick-setting gypsum plaster
consisting of a fine, white powder, calcium sulfate hemihydrate, which
hardens when moistened and allowed to dry. Sidewalk chalk is much harder
than regular chalk; in fact, will actually scratch a typical chalkboard."
I decided to test that last statement out so I went out and bought 6
different brands of sidewalk chalk, and 4 brands of regular. I took them up
to our Church where they had some old slate blackboards that they were no
longer using and conduced a test. Sure enough, all 6 brands of sidewalk
chalk left scratch marks on the board. As did 2 of the regular type chalks.
From what I've seen, most people that use chalk tend to use the
sidewalk
type because it's much larger than regular.
As mentioned above from the Crayola website, chalk is made from plaster of
Paris. According to A Dictionary of Science, Oxford University Press, ©
Market House Books Ltd 1999, "The hemihydrate of calcium sulphate,
2CaSO4.H2O, prepared by heating the mineral gypsum. When ground to a fine
powder and mixed with water, plaster of Paris sets hard, forming
interlocking crystals of gypsum. The setting results in an increase in
volume and so the plaster fits tightly into a mould. It is used in pottery
making, as a cast for setting broken bones, and as a constituent of the
plaster used in the building industry." So according to that statement,
chalk if left on a stone could set and harden into something that could
cause damage to the stone, by seaping into and filling up and expanding, anc
causing the potential to crack or break the stone.
William Spurlock
Saving Graves
http://www.savinggraves.com
----- Original Message -----
From: Debby Beheler
To: INPCRP-L(a)rootsweb.com
Sent: Sunday, September 30, 2001 8:25 PM
Subject: [INPCRP] Chalk
I hope someone will enlighten us to the damage chalk
causes. I am an advocate of using chalk to bring out
the inscription, esp. when all else fails. It seems
to me that if it is the only way to read the stone, at
least we have preserved the information contained
there when there may be no way to read it in a few
years. I have been carrying a spray bottle of plain
water with me to rinse the chalk off afterwards. I
am, however, willing to listen to the reasons not to
use chalk.
Debby Beheler
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