Hi all
I don’t want to step on any toes here, especially when Gravano is selling the stuff, but I thought if y’all wanted to do everything yourselves, here are contact details within the UK for the exact silicone that Gravano mentions in his How-To guide (Wacker Chemicals Elastosil M4641) -

Amber Composites (http://www.ambercomposites.co.uk)
+44 1773 530111
They deal in 1Kg batches, which is cool
I’ve no idea of prices yet, forgot to ask on the phone, but shes sending me a pro-forma invoice via email.

You get parts A and B for mixing - thats right - mixing and pouring yourselves!! No ready made surface layers here. And people - it is NOT easy. If you want ready made up stuff, go with Gravanos excellent deal.
I’m in the process of ordering from them right now, I’m still not sure of their total legitimacy - you’ve got to be careful in this internet day and age - but theyre looking good.
Regards

Stu

Have you considered going the diffused illumination route rather than FTIR+compliant surface?

Although my setup now is DI, at first I was using FTIR.  Let me just say, I tried making my own silicone rubber compliant surface and it is not easy.  I’d recommend ordering from Gravano if you are sticking with FTIR.

@Joobs - no I hadn’t considered that, but I’m seeing very promising results during my testing of FTIR though. Are you suggesting its a non-starter? I wouldn’t even know how to begin with DI. As I mentioned in the Hardware General Discussion - I tried using a thin layer of latex rubber and that gave me great response despite it being clouded.

I’ve had a bit of experience with fabrication using a whole variety of substances, including Silicone, and it occurred to me that if I were to mold it myself, the Silicone would cure in all the microscopic imperfections on the surface of the acrylic (Perspex) giving the best results.

BTW. Price is aroundabouts 50 UK sterling for 1Kg + 0.1Kg for parts A and B. I can imagine that would cover a serious amount of surface area even making a 5mm surface, and I doubt you’d need to make it that thick! Not a bad deal considering I paid about £20 for some opaque silicone rubber for molding a few years ago, and that was only a small pot of the stuff, maybe 200ml.

So what are the advantages of DI apart from easier implementation?

Stu

as gravano has stopped selling the silicon rubber sheets, i am wondering, why not use stock material, i have found several companies, like http://www.silikon-elastomere.de, they would sell 1 sqm for 40€, Shore 40°, 1mm thick, transparent.

does someone has tried this?

tetratoon

Concerning the DI:

beside of finding out where someone touches the screen, you can find out the distance of the Hand. We have build a DI solution where we put some IR-Lamps (no LEDs) somewhere in the room and then recorded the IR-shadows.
the more blurry, the greater the distance.
Using 2 or more cameras would enable you to be even more accurate and find out, if a finger touches the screen without FTIR, just by adding the two pics.
this technique was presented at siggraph 2005 and is probably part of the MS-Surface

http://research.microsoft.com/~awilson/touchlight/

tetratoon