John Hesselberth on sat 6 feb 99
I want to begin measuring the hardness of my glazes. About 30 years ago
I knew a millwright who had a set of "scratching pens" in his tool kit.
Each pen had a material of different hardness on the tip (diamond on down
to talc or gypsum) and you could get a good indication of the hardness of
a material by seeing which pens would scratch your material and which
would not. Does anyone know where to buy such a set? I would have
thought it would be something which Grangers might carry, but if it is in
their catalog I can't find it. Thanks to any who can help.
John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"It is time for potters to claim their proper field. Pottery in its pure
form relies neither on sculptural additions nor on pictorial decorations.
but on the counterpoint of form, design, colour, texture and the quality
of the material, all directed to a function." Michael Cardew in "Pioneer
Pottery"
Tom Wirt on sun 7 feb 99
I want to begin measuring the hardness of my glazes. About 30 years ago
I knew a millwright who had a set of "scratching pens" in his tool kit.
Each pen had a material of different hardness on the tip (diamond on down
to talc or gypsum) and you could get a good indication of the hardness of
a material by seeing which pens would scratch your material and which
would not. Does anyone know where to buy such a set? I would have
John....Try Mining supply companies. While I can't give a specific one, if
you look out in the Denver area, there's probably one. Might even call the
Colorado School of Mines in Golden, CO.
Tom Wirt
Greg Mount on sun 7 feb 99
In a message dated 99-02-07 00:42:04 EST, john@frogpondpottery.com writes:
<< I want to begin measuring the hardness of my glazes. About 30 years ago
I knew a millwright who had a set of "scratching pens" in his tool kit.
Each pen had a material of different hardness on the tip (diamond on down
to talc or gypsum) and you could get a good indication of the hardness of
a material by seeing which pens would scratch your material and which
would not. Does anyone know where to buy such a set? I would have
thought it would be something which Grangers might carry, but if it is in
their catalog I can't find it. Thanks to any who can help.
>>
Your probably better off looking in a earth science supply catalog. I know we
had these test kits in school. Or you could make your own (its probably much
cheaper.)
Good Luck,
-Raven
Douglas Adams on mon 8 feb 99
At 09:02 PM 2/6/99 EST, you wrote:
>----------------------------Original message----------------------------
"scratching pens" in his tool kit.
>Each pen had a material of different hardness on the tip (diamond on down
>to talc or gypsum)
Your description of these tools also correlate to what is know as the"Moase
Scale" or scheme of hardness, diamond being the hardest to talc the softest.
Try a welding supply house they may know what you need. hope it helps.
Douglas Adams
Ron Roy on mon 8 feb 99
If anyone finds out where to get them I need a set - so let me know where -
please!
RR
>----------------------------Original message----------------------------
>I want to begin measuring the hardness of my glazes. About 30 years ago
>I knew a millwright who had a set of "scratching pens" in his tool kit.
>Each pen had a material of different hardness on the tip (diamond on down
>to talc or gypsum) and you could get a good indication of the hardness of
>a material by seeing which pens would scratch your material and which
>would not. Does anyone know where to buy such a set? I would have
>
>
>John....Try Mining supply companies. While I can't give a specific one, if
>you look out in the Denver area, there's probably one. Might even call the
>Colorado School of Mines in Golden, CO.
>
>Tom Wirt
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Evan Dresel on mon 8 feb 99
You can probably get a hardness set from a place like Ward's minerals,
or Edmund Scientific or you can make one (or most of one) yourself.
Moh's scale of hardness is:
1 = talc
2 = gypsum
3 = calcite
4 = fluorite
5 = apatite
6 = orthoclase (potassium feldspar)
7 = quartz
8 = topaz
9 = corundum (ruby or saphire)
10 = diamond
This is a relative hardness scale in that, for instance the difference
between orthoclase and quartz is much less than between corundum and
diamond but is very useful. Ideally you test whether each substance can
scratch the other but then you need big pieces of each and need sharp
corners. Actually the way I test glaze hardness is simpler but you may
need more detail. I try to scratch the glaze with a triangular file
(hardness about 6.5). If the glaze doesn't scratch it's good; if it
scratches it isn't so good (for functional surfaces). Of course this
ignores the problem that a hard rough glaze can be marked by silverware
because it's harder than the implement.
Hope this helps.
-- Evan in W. Richland WA where it's been so windy they have to plow the
tumbleweeds off the road and when it did rain, it rained mud onto my car
from all the dust in the air.
John Hesselberth wrote:
>
> ----------------------------Original message----------------------------
> I want to begin measuring the hardness of my glazes. About 30 years ago
> I knew a millwright who had a set of "scratching pens" in his tool kit.
> Each pen had a material of different hardness on the tip (diamond on down
> to talc or gypsum) and you could get a good indication of the hardness of
> a material by seeing which pens would scratch your material and which
> would not. Does anyone know where to buy such a set? I would have
> thought it would be something which Grangers might carry, but if it is in
> their catalog I can't find it. Thanks to any who can help.
>
> John Hesselberth
> Frog Pond Pottery
> P.O. Box 88
> Pocopson, PA 19366 USA
> EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
>
> "It is time for potters to claim their proper field. Pottery in its pure
> form relies neither on sculptural additions nor on pictorial decorations.
> but on the counterpoint of form, design, colour, texture and the quality
> of the material, all directed to a function." Michael Cardew in "Pioneer
> Pottery"
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