Posts Tagged ‘pound-up’

flexi mould not so flexi.

September 26, 2009

I tried to make another model out of plaster of paris. I made sure I sealed the bottom of the mould completely this time. I poured the plaster into the mould fine and left it for a 2 days to set. The trouble started when I tried to take the Aluminium mould off.

There were 3 problems-

  1. The plaster mould wasn’t thick enough. The object im casting needs to be done on a bigger scale (at least 1:2) with a wall thickness of at least 60mm. The walls I made were way too thin. At some points the wall thickness was less than 5mm. A slight knock and it crumbled.
  2. The 0.3mm Aluminium wasn’t flexible enough so I had to pull it off with force causing the plaster to crumble.  Aluminium has the strength to hold its self upright, but it’s not flexible enough to fold back on itself like a sheet of paper or fabric. A rubber sheet would be ideal for a mould. See the video below titled “bending concrete”  and you will see what I mean with the flexible mould.
  3. Too much water in the plaster. It was slightly soft to touch after 2 days of drying. Maybe the cold weather slowed down the drying process too.

I’m still confident that this process can work but I think it just needs to be done on a larger scale. Stronger materials and thicker walls.

1 minute after being poured

1 minute after being poured

Some parts came out of the mould alright. They were about 10mm thick and had very smooth surfaces. They are the 2 larger chunks you can see below).

The remaining parts are scattered on the lawn.

blog plaster2

I had a feeling this wouldn’t work on a small scale from the start. But I had to try anyways. And at least I know what to do if I ever try this on a large scale. I will be making my 1:1 scale prototype out of different materials anyways because it needs to be transportable. Concrete would be great for the street sculpture but it won’t be suitable for the graduate exhibition.


Sand sculpting… amazing!

August 30, 2009

So after my sand models I wasn’t really sure where to take it next. It was suggested that I look into professional sand sculpting. WOW these model makers are amazing! They create such intricate design out of sand (with a limited amount of time).

I really wanted to find out what additives they were using in the sand mixture. This is a lot harder to find then i first thought because it is banned in most professional competitions. Nowadays they just use sand and water. I heard it may be a mixture of Gelatin and salt. Others say its concrete mixed with sand. But it’s my mission to find out exactly what they use. Why? Because if I can get my hand on some I will be building massive sand sculptures and skate obstacles… And making them permanent features! I will mix in way too much hardener and sculpt myself a bench. I could leave it as- is. Or I can take that design and cast myself a mould out of concrete of plaster. Could you imagine building a piece of sand furniture that hardens, and then you pick it up and take it home.

The best sand to use is sand from a river bed because it has larger triangular grains that stick together. (River = No waves!) Beach sand is not the best because the grains are rounded and smooth. This is because the waves and tides have been crashing down causing the grains to wear down over hundreds (millions?) of years.



Believe it or not but they plant explosives in these sculptures as they build them. When the competition is over… BOOM!  And I thought kicking over a sand castle was fun.

Pound- up process. Building the frames up virtically.

Pound- up process. Building the frames up vertically. Usually done the day before a competition.

They use a method called ‘Pound-up’. It basically involves building a framework out of timber. These timber walls are built up vertically until it reaches a desired height. Each section is filled with sand and is then compacted down by whacking it, jumping on it or pouring water on it. (machinery can be used to compact the sand as well.)

This is a very interesting process that I will look into further.