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repairing plaster molds

updated wed 17 mar 04

 

ken tighe on wed 15 oct 97

I have a two-piece plaster mold of a sculpture, one piece of which is
broken in half. It is made from #1 Pottery Plaster and is about one inch
thick. I would be grateful for any suggestions of how to best cement the
piece back together. thanks--Ken

VICTOR JOHNSTON on thu 16 oct 97

I'm not saying it is the best way, but I have had success with
using white Elmer's glue, or a generic form of the same. If you
go this way, you don't want the glue to come all the way to the
mold's casting surface. I try to keep it back about 1/4 inch. You'll
probably have another line you need to remove in clean up, but
my molds have held together this way.

If anyone else has a better way, I would be as interested as Ken
in learning it.

>>> ken tighe 10/15/97 05:34am >>>
----------------------------Original message----------------------------
I have a two-piece plaster mold of a sculpture, one piece of
which is
broken in half. It is made from #1 Pottery Plaster and is about
one inch
thick. I would be grateful for any suggestions of how to best
cement the
piece back together. thanks--Ken

Larry Tague on thu 16 oct 97

Slik Fix makes a great plaster repair. Carol @ Florida Clay Art Co.
1-800-211-7713 1645 Hangar Rd. #103 Sanford, FL 32773

----------
From: Ceramic Arts Discussion List on behalf of ken tighe
Sent: Wednesday, October 15, 1997 8:34 AM
To: Multiple recipients of list CLAYART
Subject: Repairing plaster molds

----------------------------Original message----------------------------
I have a two-piece plaster mold of a sculpture, one piece of which is
broken in half. It is made from #1 Pottery Plaster and is about one inch
thick. I would be grateful for any suggestions of how to best cement the
piece back together. thanks--Ken

Debby Grant on thu 16 oct 97

Dear Ken,

Aftosa makes a product called Mend-a-Mold. I've never tried it
myself but if you're interested you can call them at 1-800-231-0397.
Ask for a catalog. They've got some interesting stuff.

Good luck, Debby Grant in NH

the Gallagher's on thu 16 oct 97

Ken,
You could try using Elmers glue to set the pieces together, taking care that
no glue seeps through the edges of the crack. Then for added strength, coat
the outside with plaster bandages. The plaster should hold well to the mold,
given it is clean and not coated with anything else.
After making another positive, cast it and make a new mold!

That's what I'd do. = )

Michelle
Portland, Oregon


----------
From: Ceramic Arts Discussion List on behalf of ken tighe
Sent: Wednesday, October 15, 1997 5:34 AM
To: Multiple recipients of list CLAYART
Subject: Repairing plaster molds

----------------------------Original message----------------------------
I have a two-piece plaster mold of a sculpture, one piece of which is
broken in half. It is made from #1 Pottery Plaster and is about one inch
thick. I would be grateful for any suggestions of how to best cement the
piece back together. thanks--Ken

John Guerin on fri 17 oct 97

In a message dated 97-10-16 10:29:42 EDT, you write:

<< You could try using Elmers glue to set the pieces together >>


Elmers White glue is water soluable. Which means if your mold absorbs enough
water while in use, it could come apart. Elmers Carpenter glue will hold
better where moisture is present.

John Guerin
Tucson, AZ

Nancy Guido on mon 2 jul 01


Hi Wayne,

I did the same exact thing - I had three molds resting against the leg of my
slabroller and forgot. One broke. I used Elmer's glue to put it back
together as best I could, held it together with a blue strap my husband had
in the garage and pulled one tile out of it (I had to do some reworking) and
recast it. This was only 15" square mold though and I don't use a press.

Nancy G.

Stephani Stephenson on sat 7 jul 01


Can't remember who asked the question about how to repair a mold broken
in 3 parts. Also can't recall if mold in question was a press mold or a
slipcasting mold. but here's some general info which might be useful.

1. I would probably temporarily strap the mold together using mold
straps or glue with carpenter's glue, (see info below), and try to get
ONE more positive out of it, using water based modeling clay. I think
I would then just retool the positive (model) and cast a new mold from
it, rather than bothering to spend too much time repairing the old one.

If you are interested in retouch/repair techniques, following is some
old time info on repairing plaster molds. Source is "Materials and
Methods of Sculpture", by Jack Rich. Original copyright 1947, renewed in
1974
I am quoting, ,shortening quotes and sometimes paraphrasing here.

A. when fragments are chipped off and you want to retouch/repair areas.

1. Make sure plaster is free from dust and dirt.
2. You must 'kill' new plaster when using it for retouching a cast. Use
a weak mix of plaster, where there is more than usual amount of water.
To do this, place a small quantity of water in a vessel and add an equal
volume of plaster.
3. Roughen area to be retouched by carefully scratching with a blade.
4. Thoroughly saturate area with clean water. Use a sponge, rubber
syringe , submersion or dropper until plaster ceases to absorb water.
5. Apply 'killed ' plaster with a wooden clay tool. Smooth freshly
applied mass with a soft brush, (first wet brush with clean water, then
pass brush gently over area while plaster is fresh and plastic.)
6. Let area sit undisturbed till freshly applied area is thoroughly dry
and hard.

B .Another method, for reattaching broken pieces, consists of using a
fine grade of carpenter's glue Two coats of carpenter's glue can be used
on dry cast. First coat acts as a pore sealant. Second coat is the
cementing coat. Let first coat dry before applying second coat.. Press
fractured pieces together while second coat is still wet. Strap or bind
together till second coat is dry and glue hardens.

C. A strong solution of shellac dissolved in alcohol and burned shellac
are also used to repair and reattach broken molds.
In order for shellac to be used as a cement it must be 'burned'. In
order to 'burn' shellac, an open container is partially filled with cut
shellac, which is ignited and stirred at intervals during the burning
(note: be safe, use caution and appropriate gear)
Bubbles will form and when these cover 1/4 to 1/3 of the surface,
extinguish fire and let mass cool. On cooling , a protective skin will
form over the surface,. do not discard this.
Prime surfaces of the mold with several applications of a solution of
ordinary shellac and alcohol. After these dry, apply the burned shellac
to the plaster as the cementing agent. Rejoin pieces, as with
Carpenters glue technique.

Afterwards, remove any dried blobs of excess glue/ cement with a
sharp blade

(But , don't ya just hate it when the molds go KAPUT!!!!!)

Stephani Stephenson
Carlsbad, CA

steph@alchemiestudio.com

http://www.alchemiestudio.com

http://home.earthlink.net/~mudmistress/

Eleanora Eden on tue 16 mar 04


Hi Rachel and all,

One of the true pearly moments of clayart was when it was mentioned you can
mend molds with white glue. This has saved my life bigtime on many
occasions since. Whoever you were, thank you so much!

Actually I have thought that a slightly moist mold would take the glue
better than a completely dry mold. My thinking is that the moisture will
prevent the glue from drying too fast and the slow drying will help the
bond to mature.

Another point is to take great care that none of the glue gets onto the
working surface of the mold. That place will never be as absorbent as it
should be.

A shattered mold can be glued and strapped so that another positive can be
gotten and a new mold made. A small piece can be glued back in and the
mold continue in use as before with no problems. For big flat molds that
broke in half I glue it together and then give it a permanent edge strap
and continue using as before.

Eleanora

At 05:44 PM 2/16/04 -0800, you wrote:
>Hello Everyone!
> I just want to know if you can repair molds. I have a mold that I
> would absolutely die if it were to become unusable, at least I need to
> use it a couple more times. It has cracked, but it could easily be glued
> back together. Is this possible? Do they make some special mending
> material for this purpose? Even if it is temporary, that would be o.k.. Thanks,
> Rachel
>

Eleanora Eden 802 869-2003
Paradise Hill Road eeden@vermontel.net
Bellows Falls, VT 05101 www.eleanoraeden.com