David Beumee on mon 2 jun 03
>The question: What is the best approach as to mixing clay? Mix dry first
>and then add water or add the dry materials to water. I haven't gotten a
>set procedure and would appreciate advice from anyone familiar with this
>type of mixer.
I have mixed many tons of clay in a dough mixer, and from my experience
I always got better results by mixing the ingredients together dry before adding water.
Same holds true for using a Soldner mixer.
David Beumee
Earth Alchemy Pottery
Lafayette, CO
6/2/03 4:40:18 PM, Cindy wrote:
>I have acquired an enormous reconditioned 10HP horizontal dough mixer that
>is up and running after locating and installing a three phase converter.
>
>______________________________________________________________________________
>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.
>
Vince Pitelka on mon 2 jun 03
> I have acquired an enormous reconditioned 10HP horizontal dough mixer that
> is up and running after locating and installing a three phase converter.
> The question: What is the best approach as to mixing clay? Mix dry first
> and then add water or add the dry materials to water. I haven't gotten a
> set procedure and would appreciate advice from anyone familiar with this
> type of mixer.
Cindy -
I have used Estrins, Bluebirds, and good old commercial dough mixers. With
the Soldner mixer I always add the water first, but with those horizontal
shaft "dough mixer" types it has always worked best for me to add the dry
materials first. Always add the lightest materials first (the clays) and
then the heavier materials, the grog or sand last (if there is any).
Before going further, I must tell you that horizontal mixers are extremely
dangerous unless treated with the utmost care and respect. Keep in mind
that they are just about unstoppable, and they do not know the difference
between clay and your arm. When you install this mixer, be sure to connect
it to a heavy-duty switch box on the wall. That's in addition to the switch
on the unit. Make sure that the built-in switch is easily accessible and
easy to operate. If you have kids around, you should install a key switch
on the wall box in addition to both of these switches.
Before poking anything into the mixer, whether it is your hands or a tool,
make sure that BOTH SWITCHES are turned off. When the mixer is operating,
under no circumstances should your hand or any tool ever pass below the
level of the mixer opening (the top of the hopper). Don't ever allow any
flexibility in these policies. It is fine to dump dry materials into the
mixer while it is running, but for an added measure of safety it is an
excellent idea to purchase a piece of coarse expanded metal, with perhaps 1"
openings, and weld a light angle-iron frame around it so that it fits
snuggly over the hopper opening. For best efficiency, attach hinges at the
back. Keep the grate closed in place over the mixer opening whenever it is
running.
If you can find one, get a straight hoe - like a garden hoe, but straight
rather than bent. If you can't find a straight how, get a regular garden
hoe, and take it to someone who has an oxy-acetylene torch. Wrap wet rags
around the point where the shaft enters the wood handle. Heat the bend to
red-heat quickly and straighten it out, and then quench it in a bucket
before it burns the wood in the handle.
As you dry-mix the materials, periodically turn off both switches, remove
the expanded metal grate, and work the straight how down both sides of the
hopper along the whole length of the hopper, working up any unmixed
materials that might be down there. As soon as the dry materials are
thoroughly mixed, you can start adding water very slowly, with the mixer
turning. Use a garden hose, and dribble the water over the mixer impeller
and the churning materials, and never along the hopper walls. Move the
water stream back and forth along the whole length of the hopper.
Don't add too much water at once or it will lubricate the walls of the
hopper, and all the clay will just turn as one big slug. If this happens,
you can wait until the water absorbs, or you can dribble a little dry clay
into the gap along the hopper walls.
As you add the water, periodically turn off both switches and use the
straight hoe to work up any unmixed clay along the bottom of the hopper.
As you probably already know, the clay is plastic when it feels good in your
hands, and when you can toss a little ball of it back and forth between your
hands without it sticking. Always mix it to a consistency softer than what
you really want, because the clay particles will continue to absorb water
for a few weeks. That is part of the aging process, and the clay will
stiffen up slightly during that period. Even if it ends up a little soft,
it is very easy to let it stiffen up. It is far more difficult to work more
moisture into clay that is too stiff.
Good luck, and feel free to email me any questions about this process.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Office - wpitelka@tntech.edu
615/597-6801 x111, FAX 615/597-6803
http://iweb.tntech.edu/wpitelka/
Cindy on mon 2 jun 03
I have acquired an enormous reconditioned 10HP horizontal dough mixer that
is up and running after locating and installing a three phase converter.
The question: What is the best approach as to mixing clay? Mix dry first
and then add water or add the dry materials to water. I haven't gotten a
set procedure and would appreciate advice from anyone familiar with this
type of mixer.
Vince Pitelka on tue 3 jun 03
> When you install the cover for the mixer, I suggest a kill switch be put
in
> place that would shut off all power to the unit when the expanded metal
> cover is raised. This would shut it off if it is running, and would not
> allow it to be cut on if the lid is raised. It is a common switch, any
> professional electrician can install.
> This would be in addition to the other switches he has suggested.
I would certainly second Butch's suggestion. All the newer hopper-type
mixers have such a switch. It will be a simple modification, and a small
price for the security it will give.
Here's a little story. When I came to the Craft Center we only had two
Estrin hopper mixers. They are good machines, but suffer the same
shortcomings and dangers as any hopper mixer. A few years after I arrived
we replaced the larger Estrin with a Soldner.
A year or so before I arrived at the Craft Center they had a young clay
student who was especially cocky - seemed to feel that the normal safety
rules didn't apply to him. So he was mixing a load of clay in the big
Estrin, and as the clay rode up along the walls he was actually working it
back down in with his hands, with the mixer running. In a nanosecond of
distraction, his hand got caught behind the rotating blade, and was being
pulled down into the mixer. He was at the opposite end of the machine from
the kill switch, and could not reach it. He screamed, and amazingly,
someone was right outside in the hallway. They dashed in and hit the wall
switch before his arm was removed or before his whole body was dragged into
the blades. I don't even want to think about what might have happened.
I hope this doesn't start a series of gory mixer/pugmill stories, but even
if it does, it will be worth it to warn others of the extreme danger of
these machines if they aren't properly set up and properly operated.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Office - wpitelka@tntech.edu
615/597-6801 x111, FAX 615/597-6803
http://iweb.tntech.edu/wpitelka/
Donald Burroughs on tue 3 jun 03
You might ask Pietro Maddelena. When I was at his old studio in 1992 he was
using a dough mixer to make his clay. His website is http://www.pietro.net
Maybe Marcia Selsor knows whether he is still mixing his clay this way.
Donald Burroughs On the web @ http://www.autobahn.mb.ca/~donaldo
Louis Katz on tue 3 jun 03
These machines generally have parallel blades or sigma blades (a big
twisted blade).
My experinece is that the sigma blades work better.
I used to mix 35 batches of clay on a good day for the Archie Bray
Foundation Clay business, and package them in 50# bagged blocks.
Put the dry material in. Start with the ingredient with the highest
percentage. With a good sigma blade you can dry mix a stoneware body
for a minute or two.
Add the water all at once or come as close as you can. Measure it!!
That way you can come closer the second time. Mix only until most of
the materials a wetted. Check the consitency. While the clay is mealy
it is easy to add water. Once it is a compact mass it will want to spin
in the mixer if too much water is added.
In a good sigma mixer 7 minutes of wet mixing is sufficient, but
fifteen or more will result in better clay. It is best not to mix until
the clay gets hot, This makes gauging wetness difficult.
It your bearing have a grease fitting grease them each time you use the
mixer.
Bet very careful about safety. Make sure the mixer can not be started
while you are scraping. This means nothing can falll onto the start
switch. No one can " help". It should be turned off in two places or
require two hands to start it.
Also be careful about automatic unloading features.
If you are mixing indoors put a pickup for an exhaust system on the
cover of the mixer.
A Drywall knife makes a good tool for cleaning the inside of the mixer.
The mixer blade and the drywall knife may become very sharp with use.
Louis
lkatz@falcon.tamucc.edu
fused bowls http://www.tamucc.edu/~lkatz/LK/fused/index.htm
On Monday, June 2, 2003, at 05:40 PM, Cindy wrote:
> I have acquired an enormous reconditioned 10HP horizontal dough mixer
> that
> is up and running after locating and installing a three phase
> converter.
> The question: What is the best approach as to mixing clay? Mix dry
> first
> and then add water or add the dry materials to water. I haven't gotten
> a
> set procedure and would appreciate advice from anyone familiar with
> this
> type of mixer.
>
> _______________________________________________________________________
> _______
> 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.
>
Brian O'Neill on tue 3 jun 03
Cindy,
When I was a member of Pottery Northwest in Seattle I used to mix lots
of clay in their dough mixer. It's great for large batches (500 lb and
up). I always dry mixed first and then added water. If your mixer has a
cover (which it should), you can dry mix in the dough mixer, but it's
still pretty dusty. Once you start adding water (we used a garden hose
at half pressure), you'll get large balls of clay forming fairly
quickly. I found that it would mix quite well, but that was fifteen
years ago and I had better joints and was a wedging fiend. If you have
access to a pugmill, that would be ideal.
Congrats on your new toy! They're not easy to come by. I've looked.
Brian
Cindy wrote:
>
> I have acquired an enormous reconditioned 10HP horizontal dough mixer that
> is up and running after locating and installing a three phase converter.
> The question: What is the best approach as to mixing clay? Mix dry first
> and then add water or add the dry materials to water. I haven't gotten a
> set procedure and would appreciate advice from anyone familiar with this
> type of mixer.
>
> ______________________________________________________________________________
> 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.
Butch Welch on tue 3 jun 03
Cindy,
Vince's post and other are outstanding advise. Due to first hand knowledge
of employee getting arm almost ridded off, I would add one more safety
switch to the process.
When you install the cover for the mixer, I suggest a kill switch be put in
place that would shut off all power to the unit when the expanded metal
cover is raised. This would shut it off if it is running, and would not
allow it to be cut on if the lid is raised. It is a common switch, any
professional electrician can install.
This would be in addition to the other switches he has suggested.
If it is running and you can raise the lid, all it takes is an instant to
make a life changing mistake.
Regards, Butch
Des & Jan Howard on wed 4 jun 03
Cindy
When using our tub style dough mixer we used a four ingredient
recipe of bagged clay, rhyolite & sand.
The batch size was determined by weight of clay bags.
Water was put in mixer first, then clay bags emptied
into mixer, mixed to a very thick slip, rhyolite added next & then the sand.
The mixer made the clay up to throwing consistency.
Example (from our records):
Batch #15 19/11/83
BB clay - 3 bags @ 25 kg
17H clay - 1 bag @ 25 kg + 12 1/2 lbs
Rhyolite - 30 lbs
Silica sand - 39 lbs
Water - 14 gals
(the mix of weight units was because bags were marked in metric
& we only had an old set of grocery scales for the rest )
Des
Cindy wrote:
> I have acquired an enormous reconditioned 10HP horizontal dough mixer that
> is up and running after locating and installing a three phase converter.
> The question: What is the best approach as to mixing clay? Mix dry first
> and then add water or add the dry materials to water. I haven't gotten a
> set procedure and would appreciate advice from anyone familiar with this
> type of mixer.
--
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
http://www.luepottery.hwy.com.au
| |
|
