Dawn Kleinman on tue 26 aug 08
This is driving me crazy. I researched the archives and google. I personally
talked to the guy at US Gypsum. I was contemplating Pottery Plaster #1 or
Hydrostone. He said to use Hobby Plaster. It has more even particals.
Hydrostone is not as absorbant. I need 135 lbs. to fit into the table I
already have built.It is a 24"x48"x3.25" box. I realize I can wedge on any
sort of board but, I am far from being a master potter and recycle a lot of
clay. So the 'plaster' table is my best choice for that. I just want to know
if any of you have any ideas.
My last table was made out of plaster of paris - bad choice. It peeled and
got into the clay.
Thanks
Dawn
John Rodgers on tue 26 aug 08
Dawn,
here is how I built my table. It was built upside down - will explain in
a minute.
I made mine 2Ft X 3Ft. I built a rectangle of 2 X 6 lumber. I put a 2 X
6 cross piece across the bottom on both ends. In the corner of the
rectangle I anchored 2 inch cast iron flanges. - one each corner. These
would receive 2 inch black iron pipe legs when done. I also crewed in a
3/4 inch strip all the way around to act as support for the plaster once
cast. I put this rectangle on a big work table I used for mold making.
It was very straight, very flat, and had a formica covering on it. I
sealed the edge of the
rectangle to the table with oil clay to ensure no plaster leakage when
cast. When done, I measured the inside of the box and using a USG volume
calculator, I determine the mix I needed. The Number One choice for me
was USG #1 pottery plaster. For the purpose it can't be beat. My table
is ten years old and going strong. Just a few pits where I dropped
something heavy.
Cast the plaster with the table upside down on a smooth surface. When
done, screw the legs on and then with help, turn the table over right
side up. Yo will find a very smooth surface. After a couple of weeks of
drying it should be ready to use. Be sure to cover with a canvas - the
type art painters use - but a heavy grade - to protect the surface. Wet
the canvas before installing, and stretch tight - but not too much so.
When dry it will be very tight. You don't want to tear it. You may be
able to construct some sort of tensioning device for it.
As big as your table is, you may want to mount a cutting wire on it as
well.
I understand about wanting a large table. When I reclaim clay, I slake
dry clay in a bucket - under water, and then beat it into a wet slurry.
I then spread it about one inch thick on my plaster table. In a few
hours it pulls enough water for me to flip it over. After patting it
down, and waiting a bit more, it is ready for wedging - or running
through a pug mill
Good luck,
John Rodgers
Chelsea, AL
Dawn Kleinman wrote:
> This is driving me crazy. I researched the archives and google. I personally
> talked to the guy at US Gypsum. I was contemplating Pottery Plaster #1 or
> Hydrostone. He said to use Hobby Plaster. It has more even particals.
> Hydrostone is not as absorbant. I need 135 lbs. to fit into the table I
> already have built.It is a 24"x48"x3.25" box. I realize I can wedge on any
> sort of board but, I am far from being a master potter and recycle a lot of
> clay. So the 'plaster' table is my best choice for that. I just want to know
> if any of you have any ideas.
> My last table was made out of plaster of paris - bad choice. It peeled and
> got into the clay.
>
> Thanks
> Dawn
>
>
>
jonathan byler on tue 26 aug 08
you can use plaster, and cover with canvas to keep the clay on one
side and the plaster on the other.
Previously, you may have put too much water in your plaster when
making it. Without properly weighing the ingredients, this is often
a problem. Plaster that has been mixed with too much water tends to
be weak and flakey. If you want to mix plaster without weighing it,
take the container of your choice:
1. fill about 1/3 with water.
2. sift in plaster with your hands, avoiding letting large lumps
fall in.
3. DO NOT STIR.
4. continue to add plaster until no more will go in the water
without any plaster above the water line. Fill in around the edges
so that there are no places where the plaster does not come up to the
water line, and so that none is mounded above it. if done perfectly,
it will almost appear dry on top, looking like desert mud that is in
the process of drying up. if left to sit a few more minutes, The
very top will soak up water and leave a thin layer of water.
5. once you have added enough plaster is when you mix well for a few
minutes. Paint stirrer/mud mixer on a drill works well. you can
also stir well with your hand, reaching in and breaking up any lumps.
6. Pour into mold/table/whathaveyou.
7. for the purpose of filling up a table, you can either get helpers
to mix up separate buckets, or you can let the first batch begin to
set, and before it sets rough up the surface making at least a few
large gouges into the surface to key in the next layer. I would
advise against quickly mixing up a second batch and pouring it
directly on top of still liquid first batch, as they will cure at
different rates, and probably pull water from one to the other,
upsetting the mix and creating soft spots.
8. try to keep subsequent layers at least 1/2 inch, but preferably
over 1 inch thick, in order to assure strength in the layers.
even regular old plaster of paris, so far as I have seen, shouldn't
flake off if mixed properly, and applied at a reasonable thickness.
you might also have previously gotten an old batch of plaster. If
there are major lumps in it, while it is still in the bag, it is very
likely to have gotten wet previously, from either humid air, or water
spilled on it.
good luck!
-jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Aug 26, 2008, at 3:08 PM, Dawn Kleinman wrote:
> This is driving me crazy. I researched the archives and google. I
> personally
> talked to the guy at US Gypsum. I was contemplating Pottery Plaster
> #1 or
> Hydrostone. He said to use Hobby Plaster. It has more even particals.
> Hydrostone is not as absorbant. I need 135 lbs. to fit into the
> table I
> already have built.It is a 24"x48"x3.25" box. I realize I can wedge
> on any
> sort of board but, I am far from being a master potter and recycle
> a lot of
> clay. So the 'plaster' table is my best choice for that. I just
> want to know
> if any of you have any ideas.
> My last table was made out of plaster of paris - bad choice. It
> peeled and
> got into the clay.
>
> Thanks
> Dawn
Taylor Hendrix on wed 27 aug 08
I have a small wedging slab which weighs a ton because I framed it
with 2 x 4s. Took an entire bag of potter #1 plaster to fill. I used
the recommendation of someone on this list by attaching a good quality
canvas to the frame FIRST, inverting the frame onto a flat surface and
pouring the plaster. The canvas has held fast to the plaster for years
(I'm a hobby potter) and shows no sign of ripping or tearing.
Taylor, in Rockport TX
On Tue, Aug 26, 2008 at 5:08 PM, John Rodgers wrote:
...>
> Cast the plaster with the table upside down on a smooth surface. When
> done, screw the legs on and then with help, turn the table over right
> side up. Yo will find a very smooth surface. After a couple of weeks of
> drying it should be ready to use. Be sure to cover with a canvas - the
> type art painters use - but a heavy grade - to protect the surface. Wet
> the canvas before installing, and stretch tight - but not too much so.
> When dry it will be very tight. You don't want to tear it. You may be
> able to construct some sort of tensioning device for it.
...
Lee Love on wed 27 aug 08
On Wed, Aug 27, 2008 at 9:32 AM, Taylor Hendrix wrote:
> pouring the plaster. The canvas has held fast to the plaster for years
> (I'm a hobby potter) and shows no sign of ripping or tearing.
I have used canvas over plaster with good results too.
--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/
"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi
Dawn Kleinman on wed 27 aug 08
Thank you for you info. I'll have to keep you updated on the progress.
On Tue, Aug 26, 2008 at 8:41 PM, jonathan byler wrote:
> you can use plaster, and cover with canvas to keep the clay on one
> side and the plaster on the other.
>
> Previously, you may have put too much water in your plaster when
> making it. Without properly weighing the ingredients, this is often
> a problem. Plaster that has been mixed with too much water tends to
> be weak and flakey. If you want to mix plaster without weighing it,
> take the container of your choice:
>
> 1. fill about 1/3 with water.
> 2. sift in plaster with your hands, avoiding letting large lumps
> fall in.
> 3. DO NOT STIR.
> 4. continue to add plaster until no more will go in the water
> without any plaster above the water line. Fill in around the edges
> so that there are no places where the plaster does not come up to the
> water line, and so that none is mounded above it. if done perfectly,
> it will almost appear dry on top, looking like desert mud that is in
> the process of drying up. if left to sit a few more minutes, The
> very top will soak up water and leave a thin layer of water.
> 5. once you have added enough plaster is when you mix well for a few
> minutes. Paint stirrer/mud mixer on a drill works well. you can
> also stir well with your hand, reaching in and breaking up any lumps.
> 6. Pour into mold/table/whathaveyou.
> 7. for the purpose of filling up a table, you can either get helpers
> to mix up separate buckets, or you can let the first batch begin to
> set, and before it sets rough up the surface making at least a few
> large gouges into the surface to key in the next layer. I would
> advise against quickly mixing up a second batch and pouring it
> directly on top of still liquid first batch, as they will cure at
> different rates, and probably pull water from one to the other,
> upsetting the mix and creating soft spots.
> 8. try to keep subsequent layers at least 1/2 inch, but preferably
> over 1 inch thick, in order to assure strength in the layers.
>
> even regular old plaster of paris, so far as I have seen, shouldn't
> flake off if mixed properly, and applied at a reasonable thickness.
>
> you might also have previously gotten an old batch of plaster. If
> there are major lumps in it, while it is still in the bag, it is very
> likely to have gotten wet previously, from either humid air, or water
> spilled on it.
>
> good luck!
>
> -jon
>
>
>
> jon byler
> 3-D Building Coordinator
> Art Department
> Auburn University, AL 36849
>
>
> On Aug 26, 2008, at 3:08 PM, Dawn Kleinman wrote:
>
> This is driving me crazy. I researched the archives and google. I
>> personally
>> talked to the guy at US Gypsum. I was contemplating Pottery Plaster
>> #1 or
>> Hydrostone. He said to use Hobby Plaster. It has more even particals.
>> Hydrostone is not as absorbant. I need 135 lbs. to fit into the
>> table I
>> already have built.It is a 24"x48"x3.25" box. I realize I can wedge
>> on any
>> sort of board but, I am far from being a master potter and recycle
>> a lot of
>> clay. So the 'plaster' table is my best choice for that. I just
>> want to know
>> if any of you have any ideas.
>> My last table was made out of plaster of paris - bad choice. It
>> peeled and
>> got into the clay.
>>
>> Thanks
>> Dawn
>>
>
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