Friday, November 5, 2010

trophy prototype

received a request to show how to make a
Plaster of Paris prototype
if you do not have a Plaster lathe. . .

this post is a little more technical;
hope the very basic photos and explanation below will answer the question 
should you be interested leave a comment or e-mail us a question
will post answers once a month

~ Ceramic Matters Drawing to Scale ~

photos of a trophy we were asked to make for a wedding 

interesting concept to have trophies on the wedding tables.
some believe they deserve a trophy to stay married!

the following photos show a prototype made on the wheel
it takes a fair amount of concentration and
fast work to avoid for the plaster to get too hard
before it is all centered.
apologies, I forgot to take photos sometimes

(I blame the process, but it is probably a little bit of forgetful age as well . . .)

~ base cast on the wheel ~
Use firm plastic to make a ring
- the type lamp shades are made of, works well -
cast the base on the wheel.
Once the plaster is the consistency of cottage cheese
remove the plastic and turn to the required size
(use this piece as the "pourer" for the mould)

~ Cast Plaster on the base before turning ~
The base is painted with a release agent and 
the next section of the shape is cast
- same manner as the base -

~ Completed Top Section ~

~ Trophy Base ~

The base of the trophy was done in two phases,
because the plaster sets too fast for the complete shape to be turned in one.
Above photo, the bottom is complete and the plastic is coiled around the upper section.
Plaster is cast into the plastic;
the section below shows the plaster before it is turned

~ Cast section ~

Remember to always make "keys" and apply a release agent
if you make a piece in more than one section (as above)
the "seal" that your release agent creates,
stops the set Plaster of Paris
from absorbing the water from the newly cast section
if not, it causes for the newly cast plaster to become much harder - almost impossible to work with

~ Turned Section ~
~ Complete Prototype - top section will serve as the pouring section of the mould ~

The production moulds were made today.
Once cast, I'll post photos of the complete trophy with the handles.

6 comments:

Diana Ferreira said...

I love watching my beloved make plaster masters on his wheel. There is something mesmerising watching the plaster flying off the cutting tools, and seeing the shape emerge. But not an easy process!

Ceramic Matters said...

Hi, Diana, I get quite exhausted from the concentration because I have to work so fast...

Clementina van der Walt said...

Gerhard, you are amazing with what you accomplish..so impressive!

Ceramic Matters said...

Clementina, we are lucky we do what we love (I wish I loved to do something that makes a LOT more money . . . ha-ha!)

Glass Tiles said...

Be great to see a video of this process. I am currently researching the best way to fix a ceramic model to a wooden display base..

ceramicmatters said...

Hi Glass Tiles. We have found Silicone based products to work best, because it can accommodate the differing expansion and contraction of both the wood and the ceramic.