Guess what…

IT WORKS!

Ok i am a little excited, so here we go:

I just put some samples of the silicone skin (i’ll call it skin from now on , cause it’s really thin stuff), and it behaves like expected and enhances the FTIR effect.
That’s what i expected and it works well, quick release, perfect. It’s almost like a thin film on the acrylic.
After that (as do not have my rosco, yet ) i put some of the polyester fabric on top. It’s not supposed to be used, but works for testing this kind of layer.
It starts off a little FTIR effect, but not too much. It also does not produce any traces (i tried it with normal paper from the printer, just for fun, makes nice traces and feels like painting in ir )
Quick release as well.
The blobs are already quite bright on the bare acrylic, thats good. Nothing new for all of you, that with the silicone layer it’s much more sensitive. Thats good too, cause the layer is very thin
(i keep it between two sheets of pp foil. the nice sideeffect is, that it sticks more to acrylic than to the pp, so it can be applied to the acrylic very nicely. )

So now the next step is: MAKE A VIDEO. I know that this is worth a thousand words, but i currently do not have a screencapture tool, and just too busy with playing around with the setup
i’ll have it all done by next week, to busy from tomorrow on. But then i’ll post a video and some pics, too.

I am just happy that the approach seems to work, still some testing to be done, though.

And the best: i saved some money using 1.99 euro silicone from the hardware store (well, i still don’t know how it will work with the rear projection)

There are some things to solve:

-get a “ripple and wrinkle” free silicone skin (@tinkerman: i’ll post that process, too)
-make it large enough to fit the screen of about 60cmx70cm
-get the rosco i ordered 3 weeks ago!

And then find some space to put it all

So long and thanks for all ( the fish ? )

...and don’t forget to put a towel under your head when time traveling!

Well done! You are very close to the goal you had in mind, and yet another alternative is available for future FTIR experimenters!

It’s great to be a part of this community where there are no borders and everyone shares and gets inspired by each others experiences.

Forgive my ignorance, but do you use the Vellum to protect the projection screen from wear / cutting?

The vellum IS the projection screen. It lays on top of the acrylic.

Does the Vellum stand up better to wear and tear than a projection screen would?

No real data on that as I have never tried anything else yet.
I would say no.
In it’s uncoated or plastic protected state, it is after all a cellulose fiber material that can’t be cleaned easily. It absorbs dirt right along with moisture.
If it was in use each day by multiple users, it would look dirty.

Hey Tinkerman and Chris, how many layer have you found to be best? Two? And are you applying them directly after another or do you let it dry first before making the next? Also, do you keep your layers really thin by pressing really hard with the squeegee?

I’m still getting mixed result, that is, part of the surface becomes quite good, but other parts keep their wet shining and stick to the acrylic. Interestingly, I can often see those ‘wet’ areas already right after lifting the fabric. I’m still waiting to see if those areas will dry somehow, but they did not yet on a test piece from about five days ago…

A good flat surface helps. Flat flat flat!!! Can’t over state it. I did one on a window. It worked great! I just taped some plastic sheeting to the glass first, then went to work.
It was actually easier to drag the silicone down on the glass in the vertical.

I do two layers, and I let it cure at least a few hours in between passes. The first one helps the second one flow over the surface better.

I was looking through my supplies at work today, and i happened to be holding some vellum in my hand, and at the same time i was holding mylar in my other..... it started me to thinking..... Mylar (used for archivable building plans) has the same opacity as drafting velum. It is roughly a dollar a sheet for a 36"x48" sheet. It would eliminate the need to laminate the velum, thereby making it thicker..... I am going to use this process to create some test sheet. Only problem right now is I don’t have an FTIR settup yet....

Since Mylar is basicly a polymer or plastic already, it is resistive to cleaning supplies, very tough, will NOT rip, basicly everything that velum does, only it is WAY hardier.

Just be aware that it doesn’t diffuse light as well as vellum does. No fibers you see....
You might see the hotspot of your projector lamp, but it’s worth trying because if it does work, you could just apply the silicone and you’re done!

@ElkMonster:

About the layers: i just use one single layer of silicone. As it’s got some texture, it looks a little frosted, so if using more layers i fear to loose sharpness on the projection layer, but i am still trying out, so i might still change my opinion
So far i produced testlayers that i flatend out between two sheets of PE Foil (one side has texture) and used the same technique to flatten as tinkerman does.
I am not able to produce large sheets, but mainly because i don’t have the right size of foil yet. Keep you all up to date, but to busy at work for the moment

@Tinkerman:

I am trying to layer the Silicone on Acrylic for my LCD FTIR setup. I was going to use this one:
http://www.lowes.com/lowes/lkn?action=productDetail&productId=47970-72643-GE5000&lpage=none

Just wanted to ask if this is the right one? I need it clear so that I can see my LCD behind the acrylic sheet. My plan is to thin it out a little, roll it and then use the hair blow dryer to smooth out the surface before it fully cures. What do you think? Can you think of any risks or flaw with this plan?

OOPS! That’s not the stuff. That has a mold and mildew inhibitor and it does indeed affect the clarity!!

You need GE Silicone 1:
http://www.lowes.com/lowes/lkn?action=productDetail&productId=35166-72643-GE012X4&lpage=none

I wouldn’t use a hair dryer on this kind of mixture!!
I think it will evaporate the xylol too quickly and it will start to set with ripples in it.

I haven’t tried the pour and let it self level test yet. It needs to be really thinned to do that I think.
About 2 parts xylol to 1 part silicone perhaps… I don’t know for sure!

Here’s my recommendation to you. Mix it a little more than 1:1 and pour it on then smooth it out like sorta clear…
That’s what I did on the test piece in the video and it came out smooth enough.
It will cure rather quickly so have everything ready and do a dry run first.

I’ll have to test out the pour and let it level method very soon.

Awesome, thanks Tinkerman.

I was thinking about the “pour and self-level” approach too. Just wanted to use little heat for it to settle and level easily and smoothly. I guess the mixture may be the trick. I’ll try out ratios to see what works best, and ofcourse I’ll post my results and findings here.

I may have to read AlexP’s posts again to see what compliant surface is he using. But then again with LLP approach compliant surface is not required I suppose? Also I dont remember if the laser approach creates a plane on top of the sheet or is it actually going through the acrylic like in FTIR using IR LEDs?

GeoMan, if you’re not doing FTIR, then not only do you not need a ‘compliant surface’, you should use one. There’s no reason as it won’t due ANYTHING for you. A compliant surface (silicone, etc) is ONLY for FTIR.