Marianne Lombardo on wed 26 sep 01
Just a quick question here. When mixing plaster (for bats), do I add =
the water to the dry plaster, or the other way around? Does it matter =
(for less lumps).
Off topic completely: if anyone in the group can answer a low voltage =
wire (invisible fence) question, can you email me off list?
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
Valerie Hawkins on wed 26 sep 01
Definitely add the plaster to the COOL water. I had a very unpleasant first
plaster mixing incident not long ago. Put the plaster in my bucket, added
the water. All of a sudden the plaster 'gelled' and it was too late to dump
it into my mold. Ended up with a large bucket of rock hard plaster.
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of Marianne Lombardo
Sent: Wednesday, September 26, 2001 2:49 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Mixing Plaster Question
Just a quick question here. When mixing plaster (for bats), do I add the
water to the dry plaster, or the other way around? Does it matter (for less
lumps).
Off topic completely: if anyone in the group can answer a low voltage wire
(invisible fence) question, can you email me off list?
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Cindy Gatto on wed 26 sep 01
Hi Marrianne:
Anytime that you mix plaster you add the plaster to the
water. This is not done for a less lumpy reason even though it works out that
way it is done to make sure that every molecule of plaster gets soaked with
water. Which in turn results in after thorough mixing a smooth consistent mix
of plaster. I may add also that you should kinda sift-spread the plaster into
the water rather than adding it in by just dumping mounding scoop after scoop
until you have all your plaster in. Gradually sift-spread the plaster in
taking your time towards the end when the water has just about taken all the
plaster that it can handle. Remember you want to add enough plaster to the
water until the water just about cannot take anymore plaster and is peaking
(dry mounds sticking up out of the wet plaster slurry) out the top of the
mix. It us at this point that you want to mix. Good luck and if you have any
other questions please feel free to contact me.
Sincerely:
Mark Petrin
The Mudpit
228 Manhattan Ave
Brooklyn NY 11206
718-218-9424m
www.Mudpitnyc.com
Mudpitnyc@aol.co
Tommy Humphries on wed 26 sep 01
Always, always mix the plaster into the water by sifting it. Adding water
to dry plaster will always make lumps, that while not impossible to remove,
is no fun whatsoever.
Tommy
----- Original Message -----
From: "Marianne Lombardo"
To:
Sent: Wednesday, September 26, 2001 1:49 PM
Subject: Mixing Plaster Question
Just a quick question here. When mixing plaster (for bats), do I add the
water to the dry plaster, or the other way around? Does it matter (for less
lumps).
Off topic completely: if anyone in the group can answer a low voltage wire
(invisible fence) question, can you email me off list?
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
iandol on thu 27 sep 01
Dear Marianne Lombardo,=20
Always, always sift the plaster into the water. Allow the water to =
slake, that is, thoroughly wet the powder, before stirring. Give the =
bucket of mixing bowl a jog or two before mixing to help float air =
bubbles to the surface.
hope that helps,
Ivor Lewis, Redhill
Brant Palley NMCLAY.com on thu 27 sep 01
for best results always add plaster to water.
Always weigh out the amount of plaster you need, then look up the water by
weight percentage. For example USG # 1 Pottery for making molds uses 70%
water to plaster. So 10 lb. of plaster requires 7 lb. of water. First weigh
out the plaster you need, take that amount and multiply it by .7,(point 7),
(7/10) this gives you how much water to use.
Generally speaking the larger the percentage of water the softer and more
absorbent the plaster will be. The harder the plaster the less water used.
Hot water will speed up the set time and cold water will slow it down.
Place the water in a suitable sized container. Always add plaster to water.
Pour the plaster into the water and let slake for one minute. Mix by hand
or with a Jiffy Mixer, being careful not to suck air into the plaster. When
the mixture is lump free it is ready to pour; don=92t wait for it to start t=
o
thicken
Robert Dye on thu 27 sep 01
Always add the dry plaster to the water. Every book I have read emphasizes
this, and I have always done it this way, with no problems. I have tried
it the other way, making a big mess. I use a french wisk to stir it up,
and that gives me a thick creamy consistency, with no lumps. Bob Dye
Phyllis Kloda on thu 27 sep 01
On 9/26/01 2:49 PM, "Marianne Lombardo" wrote:
> Just a quick question here. When mixing plaster (for bats), do I add the
> water to the dry plaster, or the other way around? Does it matter (for less
> lumps).
>
> Off topic completely: if anyone in the group can answer a low voltage wire
> (invisible fence) question, can you email me off list?
>
> Marianne Lombardo
> Omemee, Ontario, Canada
> email: mlombardo@nexicom.net
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Marianne
You're probably getting tons of answers but here goes. I am a mold maker and
work with plaster constantly. The best way is to add the plaster to water,
sifting it slowly through your hands to get lumps out. I usually weigh out
water and plaster, the ratio being a 10 to 7 ratio. In other words 10 lbs.
Of plaster to 7 lbs of water. Or 1 lb of plaster to .70 oz. Of water.
You get a better life span of the mold/ bat and more durable objects. I use
molding plaster and hydrocal- 1/2 and 1/2 mixture. I use lukewarm water to
mix in too. (water temp may vary according to your location) (I just moved
from Wyoming to Ohio and am seeing that the humidity difference here is
changing the set up time on plaster) After sifting your plaster in, gently
squeeze the lumps out then with an agitating motion mix the plaster to a
heavy cream-type consistency (trace your finger over the top and you'll see
a slight trail) then pour.
Be gentle in mixing so as not to add air. Once the plaster is poured into
your mold, tap the mold to get air to rise to the surface.
Hope this helps.
Phyllis Kloda
Ohio Wesleyan University
Klyf Brown on thu 27 sep 01
The method I was shown that is the easiest to remember and portion
out is this; place water in your mixing container, sift in the plaster
slowly, it will fall as you add more. When a small island of dry plaster
rears it's head above the water, you have the right portions. Mix as
stated in the post below.
Klyf Brown, in a dryer desert this week.
9/26/01 10:36:53 PM, "Brant Palley NMCLAY.com"
wrote:
>for best results always add plaster to water.
>
>Always weigh out the amount of plaster you need, then look up the
water by
>weight percentage. For example USG # 1 Pottery for making molds
uses 70%
>water to plaster. So 10 lb. of plaster requires 7 lb. of water. First
weigh
>out the plaster you need, take that amount and multiply it by
.7,(point 7),
>(7/10) this gives you how much water to use.
>
>Generally speaking the larger the percentage of water the softer and
more
>absorbent the plaster will be. The harder the plaster the less water
used.
>
>Hot water will speed up the set time and cold water will slow it
down.
>
>Place the water in a suitable sized container. Always add plaster to
water.
>
> Pour the plaster into the water and let slake for one minute. Mix by
hand
>or with a Jiffy Mixer, being careful not to suck air into the plaster.
When
>the mixture is lump free it is ready to pour; don’t wait for it to start to
>thicken
>
>___________________________________________________
___________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
>
| |
|
