Fredrick Paget on sat 15 apr 06
Michail Wendt has described the screeding process, now as to the
light weight - there is a product used in boat building called
microballoons that comes in either glass which is white or phenolic
which is sort of maroon. It consists of tiny hollow spheres filled
with air. It is a dry very light powder.
You can mix it into the plaster to bulk it up and reduce the weight.
With plaster you will have to experiment to find the right mix .
Generally it is used with epoxy resin.
Googleing "microballoons" brought up 50900 hits.
--
From Fred Paget,
Marin County, CA, USA
fredrick@well.com
Charter Member Potters Council
John Fitzgerald on sat 15 apr 06
I am a contractor/woodworker and I need to reproduce old plaster moldings.
Sections generally about 1 -- 4 feet in length. All ceiling moldings.
There are too many varied styles and sections to have it reproduced by
milling, as the creation of each knife for each style adds up, monetarily.
I would like to do it with a very lightweight plaster if possible or I am
open to any suggestions and appreciative of any imput in this regard.,
I can remove pieces in order to create molds if such a path is best. I have
always felt that it is a problem that is very much under-addressed in
period-home restoration. The approach used to be to 'run' moldings, meaning
they would be plastered and profiled(made) in place.
If I could discover an appropriate inexpensive light material I would do
this, or again will try anything (novel or not) that works.
Thanks, John.
Lynn Goodman Porcelain Pottery on sat 15 apr 06
I would make a latex mold and back it with plaster:
1) Spread latex over the positive in successive thin coats. You need
the final latex to be at least 1/4" thick.
2) WITHOUT removing the positive from the latex, spread plaster in an
even coat--about 1" thick. When it gets hot, remove the positive.
3) Cast plaster into the latex mold. Peel away the latex from the new
cast to remove.
Alternately, you could make a "jolly/jigger" type template that doesn't
attach to an arm:
1) cut an outline of your shape in a metal plate.
2) cut the same profile in a piece of wood; bolt the two together so
the metal protrudes by maybe 1/4".
3) Deposit a thick strip of partially set up plaster (stiff enough to
hold a shape) on a surface which will release the plaster when it
cures; drag your template through the stripe. If you did it right,
you'll have a shaped plaster strip in the desired shape.
Lynn
On Apr 15, 2006, at 12:12 PM, John Fitzgerald wrote:
> I am a contractor/woodworker and I need to reproduce old plaster
> moldings.
> Sections generally about 1 -- 4 feet in length. All ceiling moldings.
> There are too many varied styles and sections to have it reproduced by
> milling, as the creation of each knife for each style adds up,
> monetarily.
> I would like to do it with a very lightweight plaster if possible or I
> am
> open to any suggestions and appreciative of any imput in this regard.,
>
> I can remove pieces in order to create molds if such a path is best. I
> have
> always felt that it is a problem that is very much under-addressed in
> period-home restoration. The approach used to be to 'run' moldings,
> meaning
> they would be plastered and profiled(made) in place.
> If I could discover an appropriate inexpensive light material I would
> do
> this, or again will try anything (novel or not) that works.
> Thanks, John.
>
> _______________________________________________________________________
> _______
> 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.
>
>
Lynn Goodman
Fine Porcelain Pottery
548 Court St.
Brooklyn, NY 11231
718-858-6920
Cell 347-526-9805
www.lynngoodmanporcelain.com
David Martin Hershey on sat 15 apr 06
Hi John,
A number of years ago I read an article in
Fine Homebuilding on just what you are trying to do.
It was for a restoration project on a colonial mansion.
I believe they made silicone rubber molds of intact
molding sections, and cast the replacements in regular
builders plaster.
Then they cut tin profiles to act as knives to smooth the
joints and inside corners.
Try going to Finehomebuilding.com, and searching their
archives. They have every article available on disk, if you
can find it. (poor search engine)
Another suggestion would be to join their discussion board,
"breaktime discussion" at the bottom left under Resources,
and post a message. Lots of help there.
Best, DMH
Beautiful Hermosa Beach CA USA
>I am a contractor/woodworker and I need to reproduce old plaster moldings.
> Sections generally about 1 -- 4 feet in length. All ceiling moldings.
Michael Wendt on sat 15 apr 06
John,
Go to the Library and find a book entitled "Plaster
Mold and Model Making"
The technique to make plaster moldings
is the use of an extrusion die on a smooth release
surface like Formica with a straight edge as a guide.
The template is drawn and cut to exactly match the
existing molding. It is set in a jig to keep it square
to the work and plaster is mixed, allowed to partly
set tot eh plastic state and rough formed into a log
on the table. The die can then be drawn along to finish
extruding the molding.
Before you make really large ones, try a few simpler
shapes to get the timing and skills practiced and
refined. Once you know the technique, it will be a
valuable an powerful tool for what you are doing.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
John wrote:
I am a contractor/woodworker and I need to reproduce
old plaster moldings.
Sections generally about 1 -- 4 feet in length. All
ceiling moldings.
There are too many varied styles and sections to have
it reproduced by
milling, as the creation of each knife for each style
adds up, monetarily.
I would like to do it with a very lightweight plaster
if possible or I am
open to any suggestions and appreciative of any imput
in this regard.,
I can remove pieces in order to create molds if such a
path is best. I have
always felt that it is a problem that is very much
under-addressed in
period-home restoration. The approach used to be to
'run' moldings, meaning
they would be plastered and profiled(made) in place.
If I could discover an appropriate inexpensive light
material I would do
this, or again will try anything (novel or not) that
works.
Thanks, John.
John Jensen on sat 15 apr 06
I did see a book once which discussed at length the techniques for
running plaster molding in place. I can't remember the title or
author, but maybe just knowing it's out there will help. I'd guess
the book was published in the late eighties or early ninties..
Best wishes.
John Jensen, Mudbug Pottery
John Jensen@mudbugpottery.com
http://www.toadhouse.com http://www.mudbugpottery.com
http://www.mudbugblues.com
JOYCE LEE on sat 15 apr 06
ok
----- Original Message -----
From: "John Fitzgerald"
To:
Sent: Saturday, April 15, 2006 9:12 AM
Subject: Making Plaster Molds
> I am a contractor/woodworker and I need to reproduce old plaster moldings.
> Sections generally about 1 -- 4 feet in length. All ceiling moldings.
> There are too many varied styles and sections to have it reproduced by
> milling, as the creation of each knife for each style adds up, monetarily.
> I would like to do it with a very lightweight plaster if possible or I am
> open to any suggestions and appreciative of any imput in this regard.,
>
> I can remove pieces in order to create molds if such a path is best. I
have
> always felt that it is a problem that is very much under-addressed in
> period-home restoration. The approach used to be to 'run' moldings,
meaning
> they would be plastered and profiled(made) in place.
> If I could discover an appropriate inexpensive light material I would do
> this, or again will try anything (novel or not) that works.
> Thanks, John.
>
>
____________________________________________________________________________
__
> 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.
Doug Trott on sun 16 apr 06
John -
check out www.oldhousejournal.com. The Old House Journal has become a bit
of a "lifestyle" magazine lately, but it has documented many skills
appropriate for historic preservation, including "running" plaster moldings.
I'm sure you will also find links to books on these topics as well.
Doug
("new guy" on clayart)
>From: John Fitzgerald
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Making Plaster Molds
>Date: Sat, 15 Apr 2006 12:12:52 -0400
>
>I am a contractor/woodworker and I need to reproduce old plaster moldings.
>Sections generally about 1 -- 4 feet in length. All ceiling moldings.
>There are too many varied styles and sections to have it reproduced by
>milling, as the creation of each knife for each style adds up, monetarily.
>I would like to do it with a very lightweight plaster if possible or I am
>open to any suggestions and appreciative of any imput in this regard.,
>
>I can remove pieces in order to create molds if such a path is best. I have
>always felt that it is a problem that is very much under-addressed in
>period-home restoration. The approach used to be to 'run' moldings, meaning
>they would be plastered and profiled(made) in place.
>If I could discover an appropriate inexpensive light material I would do
>this, or again will try anything (novel or not) that works.
>Thanks, John.
>
>______________________________________________________________________________
>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.
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