AudioTouch and more

Pouring the Silicone

Posted by: cerupcat on: October 12, 2007

Well, the silicone arrived today. It took 5 days from the time of ordering online. I’ve done a lot of research, talking to others that have poured silicone and watched a couple videos so I was prepared for what I needed to do.

The best video to date is from Blaxwan and it really provides great documentation and information on how to pour the silicone.

Here are a couple things not mentioned in the video that I would like to add:

1) Make sure that you read the directions carefully on the package.

2) Measure out the portions of A and B by weight (not volume) with a gram scale. The main reason most people don’t get the silicone rubber layer right the first time is due to the A/B ratio being incorrect.

3) Be patient, but work fast. Although this particular silicone doesn’t fully set for an hour, it does start to set in about 30 minutes from the start of mixing the A and B portions together. After 30 minutes, it becomes harder to smooth/level out the silicone so make sure to use your time wisely and plan things out beforehand.

4) Once dried, DO NOT TAKE THE SILICONE OFF THE ACRYLIC. The idea is for the silicone to have no bubbles and stick to the acrylic. By taking the silicone off when it dries, air bubbles will be introduced in between the silicone and acrylic which is not ideal.

My Setup:

The sorta Clear 40 arrived in this little package with two different parts. Part A is the tub with the silicone which is sticky and thick, and Part B is the activator which is a liquid.

Before starting, I prepared the table (like the video) by putting an old table cloth over it, and laid newspaper down and put the acrylic on top. It’s hard to see the acrylic since it’s very transparent. Since I didn’t have U-channels to put on the sides of the acrylic for leveling the silicone, I put layers of blue tape on each side. I continued stacking tape until it measured 1mm above the acrylic which came to 8 layers of tape on each side.

I used a straight metal beam (purchased at Home Depot for $2) for leveling the silicone. The beam fits over both sides of the acrylic where the tape is and glides smoothly over the acrylic about 1mm above it.

Here you can see a closer picture of the tape and setup. Once the leveling of the silicone is completed, I placed blue cups around the acrylic in order to hold up cardboard and a cloth while the silicone cures (dries).

Once the silicone is leveled out and the cups are in place on each side, I placed a cardboard box on top of the cups. This gives room for the silicone to cure as a sheet will be placed on top of the box.

Finally, another old table cloth was positioned on top of the cardboard. This is necessary so that the silicone doesn’t acquire dirt as it sets.

5 Responses to "Pouring the Silicone"

Great work Cerupcat!
I’m happy that my video was useful somehow, now please let us know how the silicone rubber layer is working for you!
:o )

why do you use the silicon rubber layer??? doesn´t the FTIR-Technology work without the silicon layer for your project?

regards
seb

FTIR works without silicone, but a compliant surface (like silicone rubber) is really needed in order to get good “blobs” when dragging. Without silicone rubber it’s hard to keep blobs while dragging.

ah ok!!! …thanks for the fast answer

and does the silikon feel “smooth” and hard by dragging the fingers over or is it more like rubber and soft materials with a lot of resitance while dragging?

I don´t understand what it´s the silicone rubber?

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About

My name is Seth Sandler and I am an undergraduate student finishing a Bachelors degree in Interdisciplinary Computing and the Arts with an emphasis in Music at the University of California, San Diego.

I'm currently doing research and developing a Multi-user, Multi-touch musical interface. This blog space will serve as both a documentation of my own progress as well as an informational space for others to learn and peruse their own Multi-touch techniques and applications.

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Want to build your own multitouch surface table? Go to NUI Group to find out how.

AudioTouch Current Setup

Unibrain Fire-i Color camera
$22.20
Swann Wide-angle IR Camera Lens
$19.33
50 Osram SFH485 IR LEDs
$27.53
4 Breadboards
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Acrylic 24" x 36"
$43.91
Wood Frame
$18
Sorta Clear 40 Silicone Rubber
$45
Rosco Grey Screen
$30.87
Projector Mirror
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