Hey Tinkerman,
im making testing your method to make a compliant surface… i first thinned out my silicone and then i applied it to vellum tracing paper… in applying to the paper i noticed that ripples were starting to occur, how did you prevent this.

ohh btw i have my edges taped as well..
Taha.

I didn’t thin it out. That might be doing it. You shouldn’t have to thin it.

Hey Tinkerman,

Great work, this looks really promising. I was wondering; since you have some experience with the materials by now, do you think it’d be possible to make a textured silicone layer on a transparant surface like thin laminating sheet? I’m building a FTIR LCD, so I need my compliant surface to be transparant, yet I’m hestitant to go with the “traditional” silicone rubber approach.

Your input on this would be greatly valued. ( :

Tinkerman - 24 June 2008 03:44 AM

I didn’t thin it out. That might be doing it. You shouldn’t have to thin it.

Hey tinkerman i tried it again without thinning it out and still it creates ripples after the first pass…
did you lay your vellum sheet over your acrylic and then apply the silicone on the vellum? cause lack of electrostatic focre may be playing a role, cause i have mine laid down on a sheet of wood.

Taha

Sure you could apply it to any flat surface. Cerupcat used frosted polycarbonate and two part silicone.

Tinkerman - 24 June 2008 11:09 AM

Sure you could apply it to any flat surface. Cerupcat used frosted polycarbonate and two part silicone.

How are the transparant properties when it’s textured? I can imagine that it adds a bit of noise, right?

hi,

i’m doing a deformable surface(curtain to be exact) for my multitouch system and i’m wondering if the fabric that you guys used in this thread can be used for DI? as i’m looking for an alternative for my current curtain as it is using a shower curtain. my problem is my finger blobs aren’t defined enough for the webcam.

cheers

@icecube:
I’m using drafting vellum, not fabric. It’s a paper prduct made from cotton fibers. It’s great projection material.
After applying the textured silicone to it, I cannot see any reason that it wouldn’t work with a DI setup. In fact, I think it would lend itself to that setup.
Try it and let us know how it works. I’d love to hear.

@Taha:
I masking taped down a sheet of plastic over some smooth laminate covered wood. Then I masking taped down the sheet of vellum on the top and bottom edges.
I pulled it a little tight as I taped the bottom edge, that way the sheet was nice and taught and firmly held in place. Then I applied the silicone and textured it.

If you’re not taping it in place, that could be the problem with the ripples.

@ Emiel:
It’s a beautiful projection surface. It’s translucent. It helps diffuse the image as does the drafting vellum. They both work together to produce a nice clean image.
If you use a fabric that is too course to apply the texture, it start’s to blur the image somewhat.
It doesn’t add noise to the background on my FTIR rig. With DI it may add some noise, but as mentioned, that may be a benefit due to the added sensitivity.

hi tinker,

just wanna clarify..

1) so u are using drafting vellum then coat it with silicone and use nylon fabric to “mould” it as the texture?

2) the first video on the first post u stated silicone coated cloth, actually i want to know how you get that? is it not ideal for the projection?

cheers

It works! Well, kinda…

My previous attempts haven’t got any better after a few days of curing, so I decided to make a new sheet. But this time, one fortunate accident may have made the difference: while making the silicone, I had to leave the office in a hurry, and forgot to peel off the fabric. So, the silicone cured overnight with the fabric on it, which left me with a nice pronounced texture on the sheet of paper the next morning.

This one sticks much less to the acrylic, but it still does. The funny thing is that I ended up with two well defined regions that behave very differently. Check the image on the right.

In the darker area, the silicone layer behaves perfectly. In the lighter areas, it tends to stick a lot. I could be a matter of the layer’s thickness, but how do I get the magic thickness evenly?

I might also try different fabrics and silicones.

What keeps me trying to get this technique right is the incredible brightness you get from the blobs. I mean, look at those blobs! I hope I’ll get it right.

icube - 28 June 2008 01:33 AM

hi tinker,

just wanna clarify..

1) so u are using drafting vellum then coat it with silicone and use nylon fabric to “mould” it as the texture?

2) the first video on the first post u stated silicone coated cloth, actually i want to know how you get that? is it not ideal for the projection?

cheers

@ icecube
I tried it with cloth, but I couldn’t find a fabric that was well suited for projection. Then I tried the vellum and stayed on that course. Vellum is a good projection medium.

@ GFantini
It looks to me like the silicone didn’t get applied evenly. That dark spot in the upper left. I can see a definitive line that shows the silicone runout point. Looks like you applied it right to left in the pic.
It’s tricky.
The best technique I found is to have TOO much silicone to start with.
That way, there is a nice even, fat bead of it flowing out from under the squeegie blade. Just wipe any excess on a paper towel or rag. It’s important to have a nice even layer that can be impressed with texture.

Also try to find GE Silicone 1 like I use. It works perfect and it’s the original RTV silicone formula. GE invented the stuff in the 70s so you can’t go wrong with their product.
It’s not uncommon for a bit of stickiness for the first day or two. It’s all dependent on the % of relative humidity in your area. It cures quickly above 40% . The moisture in the air accelerates the cure time.

Keep trying.. you’ll get the results you’re after.

Great work Tinkerman, keep paving the way.
Question… what is the “clear protective laminate” layer you had applied to your vellum sheets exactly?

jay w. - 29 June 2008 03:05 PM

Great work Tinkerman, keep paving the way.
Question… what is the “clear protective laminate” layer you had applied to your vellum sheets exactly?

Thanks…

I had it done at Kinko’s copy store. They laminate documents, photos etc. They looked at me weird when I said Hi. Could you take these two sheets of vellum and run them through the laminater together?
They did it, I cut it apart around the perimeter of the vellum and I ended up with two nice sheets of lamianted on one side vellum! I put the textured silicone on the vellum side and I have a liquid and grime proof compliant surface that I can project onto! I applied a sheet of IR blocking window film to the laminate side of the second sheet. I use that surface in ambient daylight rooms. It really helps the contrast.

They both produce bright blobs.

Good idea with the simple laminate layer.
Your IR blocking window film , is it tinted or clear?
I’ve looked on line for IR blocking plastic film clear, and not much luck. Only commercial products still being tested. I know theres gotta be something out there, it can’t be that hard to make clear IR blocking film with todays technology.

Just a note on some of the remarks about whether the silicone changes in time; Using silicone to seal glass tops for jewelry showcases amoung other things, I know that in time the silicone will turn slightly opaque. I’ve used many types to get the longest clearity and theres not much difference in the brands. Perhaps theres others that are designed to stay clear, but I’m not aware of them.

As cheaply as I can produce this compliant layer, I don’t mind if it has a limited lifespan. If it lasts for a few months I’ll be quite pleased.

The film is 35% VLT (visible transmitted light) I got it at Checker Auto.

Take a look at this stuff from Gila. It looks promising.
Check the “Heat Control Window Film” section at the top of page.
Ther’s one called “Light” Read the specs on that one. There is a key at the bottom of that page.
The “Light” film is 49% VLT and has 51% Total Solar Energy Rejection. That includes IR.

http://www.gilafilms.com/Residential/window-film-support-performance.htm