Prof.'s DIY screen

[Prof.]

MississippiMan wrote:

Silver not dampened at all will be too reflective. Ditto Aluminum. I cannot see how this is missed your reasoning.

It hasn't...In my reasoning, the major part of the "dampening" will be done by the top coat..The aluminium base coat would be left unadulterated as much as possible, to give as much reflectivity initially, as possible..

I bet you don't recall a horrid Screen Paint (Top Coat) called "OptiCoat". Cloned off the "Anti-Camera" Licencse Plate Spray Paint concept, at it's "best' what it did is almost exactly what your idea will do. And that ain't gonna be good.

I recall the name "Opticoat" but I'm not familiar with the principles involved..

First surface reflectivity is too intense to deal with without some degree of muting. Call it whatever else you care to....if your mixing Aluminum or Silver in ANY Clear or matte, you WILL be dampening the reflectivity to some degree. Some coatings more than others, but to date, not even a "Clear" has been shown to dry "perfectly clear". That's just not disputable. And even this Thread's Authors have repeatedly said how introducing a Clear to Aluminum destroyed the effect they wanted to keep.

So to all intents and purposes, the reflectivity of the aluminum will have some muting in the clear base to begin with..

Prof, I'd like to think that is what your after, but your description of same, how you plan to go about it, and why you think it should work quite frankly does not measure up to what I've come to know as your level of well reasoned out thinking

.
MMan..I think you may have misinterpreted the principle of my design..
As you are aware, if you put a coat of white paint on a clear piece of acrylic, and then shine a bright light at it, you will see some light transmission through the back..
If you then place a mirror behind that panel, some of that light will be reflected back..or as in your case, painting directly onto the mirror..
I'm just basically replacing that mirror with an aluminium one..The top coat will be just plain white.. .

A Ultra Fine Grain SM base with an extremely translucent, whitened Top Coat should do exactly what you want.

As I've just stated above.. That's exactly what I'm doing..

It is your time and effort spent, Prof. No natter what, I wish you nothing but good results. By all means, find a "New Way" to change the Laws of Physics. Unfortunately, with paints, I'm fairly certain we are pushing the limits now that most of the individual ingredients are being qualified and quantified so throughly. I'm not so much trying to force an opinion on you as trying to head off wasted effort by virtue of having "Been there, Done that." myself in pursuit of the same goal.

I thank you for your concern and best wishes..
I don't profess to be an expert in screen design, so I appreciate your constructive input..
Actually I am one who likes to try and break the laws of physics from time to time..

[Prof.]

<^..^>Smokey Joe wrote:

Prof, the Dulux code for the above spectrum that mech posted.

620-04912 vivid white

Ah.yes..I've seen that Vivid White..Thanks very much for that.

Please note, I have already tried adding pure aluminium paste. At the moment though controlling the reflective balance is proving difficult. Mech has some of my mix results.
The fundimental problem is a physics one, where the blue end of the spectrum scatters more readily(tis why the sky is blue no less), although the spectral response of pure ali is fairly flat the combination of TiO2 and Aluminium creates a different spectral response. ie a blue push result. Just adding tints hasn't so far been so succesful where the result is fairly lumpy.

Thanks for that info. Smokey Joe..I take it that this different spectral response is caused when you combine the aluminium and Ti02 together in a mix.?.
I wonder if this would still occur when the Ti02 is layered on top of the AL.?

I think we are at the point of looking for a third element, natural tints aren't really it either as most don't push in the ideal way.

I don't think the addition of WOP (White Opal Pearlescence for those who are not familiar with the term) would help either, since If I remember correctly, it has a slight blue push also..
MMan might know more about that..

[thxgoon]

Prof. wrote:

As you are aware, if you put a coat of white paint on a clear piece of acrylic, and then shine a bright light at it, you will see some light transmission through the back..
If you then place a mirror behind that panel, some of that light will be reflected back..or as in your case, painting directly onto the mirror..
I'm just basically replacing that mirror with an aluminium one..The top coat will be just plain white.. .

Coooool! I will be following this thread with great interest. So would it be possible to say that such a screen would actually increase contrast as the amount of light that would pass through the top coat and be reflected would essentially decrease with less light output? (Just speculating here.. really just wanted to subscribe to this thread )

[Prof.]

thxgoon wrote:

So would it be possible to say that such a screen would actually increase contrast as the amount of light that would pass through the top coat and be reflected would essentially decrease with less light output? (Just speculating here.. really just wanted to subscribe to this thread )

thxgoon..It is a well known fact that grey screens generally produce very good blacks..
This also applies to the current mixes for the BW screen..

With the silver based/white top coat screen I'm looking at, it will still be essentially a type of grey screen..The only difference is that to the naked eye, it will look white..
Therefore, it will still produce the very good blacks, whilst still maintaining very good whites..Which in effect will give better contrast..

There is no less light output with this design, over a white screen, infact the opposite..It should reflect more of the light back, through a slight increase in gain..At least, that's the theory.

[cynical2]

Prof, I didn't read every word of this thread...but, is mixing up some small panels still not an option rather than going all-in with a full screen? This feels to me like something that will take a good bit of trial and error to get to something that performs as you hope it will.

Please don't take this as me doubting your capability/understanding/creativity, etc...I just know how much work has gone into many of the final solutions that have appeared here and other places on the interweb. From the recent extensive use of color measurement equipment going back to mixes that were driven via screen images and trial-and-error...they all have one thing in common...I don't think anyone hit on the "best" mix the 1st time around. Developing a good mix is just an iterative process, and I don't want you to be frustrated if your first cut doesn't float your boat. You may find that your ideas result in a good solution (or maybe not)...but having more than one crack at it definitely increases your chances.

OK, enough rambling.

Keep us updated, and most of all, GOOD LUCK!!

[Prof.]

Thanks for your concern Jim, but I might have been a bit flippant when I said I wouldn't be doing any tests..
I won't be doing completed panel tests as such ( unless I can get hold of a good quantity of silver, other than AAA) but more translucency tests than anything..

For the base coat, it's just a matter of applying a silver /clear acrylic mix..The ratio probably not being so critical..
It's the top coat that going to be the critical aspect..So I was planning on making up several small mixes of white and clear of varying ratios, and applying them to small pieces (maybe 6"x6") of clear acrylic sheet..
One of the pieces would be painted with White only..

These small test sheets would then be placed in the projectors light path, near the normal screen position whilst projecting white light..
Then checking the amount of light transmission through each piece..

Basically what I'm looking for is the panel that just starts to allow more light through, than the plain white panel..

It's pretty rough and unscientific I know, but should give me a fairly good starting point..
Then I'll make up a larger, fully finished panel with that ratio, and see how it performs..

I should add that I don't think I'm going to able to use the AAA...It would seem that it's not going to be bright enough to give the required reflectiveness..

[<^..^>Smokey Joe]

Prof, you could find some of my previous work interesting. Led to some of my madness I now exibit

Also note I have looked at paint thickness as a filtering effect. I think the polynomial is in the first thread.

Filtered Coffee and Screens
An Experiment in shades of Grey

[Prof.]

<^..^>Smokey Joe wrote:

Prof, you could find some of my previous work interesting. Led to some of my madness I now exibit

Also note I have looked at paint thickness as a filtering effect. I think the polynomial is in the first thread.

Filtered Coffee and Screens
An Experiment in shades of Grey

That is an EXCELLENT!! write up Smokey Joe. ..Very comprehensive and informative...and very interesting as well..
It certainly has made me re-think the whole idea of having an aluminium reflector base..

The filtering aspect, I find very appealing, particularly the control you can have over it by adding additional layers if needed..

But it does beg the question though
..How do I convert those weight ratio's to usable volume measurements?
It would seem that there is only a minute amount of the tints added to the clear, to obtain the results you speak of..

I found this in your write up..

Raw umber would scale up to 1000litre of clear coat with 2.5grams of tint.

Is that correct?..1000 litres to 2.5g.!!?That is an infinitesimal amount of tint!!

Would there be anyway you could convert the amount of tints to be added, in the form of drops?
For example...10 drops of raw umber to 1 litre of clear..

Another interesting aspect to your design is that you used a gloss white base coat..
I can see that would give you some reflectance..which has given me an idea I would like to run past you..

My current screen is Melamine based with a clear acrylic top coat..As you may know, Melamine is a very white material that has a satin sheen..hence the reason for the top coat..
Do you think that the satin finish of the Melamine could be used as a mild reflector, similar to your gloss finish?..Or wouldn't it be strong enough to reflect light back through the top coat?

If the former were the case..then I could use my existing screen, just with the addition of the tinted top coat..
Considering that I'm already getting good blacks and whites from the Melamine white, probably all I would need for the tints would be raw umber and yellow oxide.?..Does that sound workable?

Edit...For example...10 drops of raw umber to 1 litre of clear..
What I should have said is the measure that a paint Company/Supplier would use , when tinting bases..
I think that is the only way that I will be able to get tints added..they wouldn't sell the tints seperately..

[fisher191]

<^..^>Smokey Joe wrote:

Prof, you could find some of my previous work interesting. Led to some of my madness I now exibit

Also note I have looked at paint thickness as a filtering effect. I think the polynomial is in the first thread.

Filtered Coffee and Screens
An Experiment in shades of Grey

Hello Joe,

I have been reading through your (extensive!) work both here and at AVS. I have been thinking about an upgrade to my flat white diy screen.

It is very frustrating to read through the forums about paint brands that aren't available in NZ.

What screen/finish do you currently use yourself? What would be your recommendation for paints I can find here in NZ?

Cheers,
Greg

[mechman]

<^..^>Smokey Joe wrote:

Prof, you could find some of my previous work interesting. Led to some of my madness I now exibit

Also note I have looked at paint thickness as a filtering effect. I think the polynomial is in the first thread.

Filtered Coffee and Screens
An Experiment in shades of Grey

Smoke,

While I realize it may be a pain in the posterior, could you cut and paste these here? I'm currently on an AVS sabbatical which I hope lasts forever! And I'd love to read them! I also have some questions for you that I may post in the pj forum about calibrating my Mitsubishi HC3000. Which doesn't have a service menu.

Sorry for the intrusion Prof.!

[<^..^>Smokey Joe]

Most of this stuff led me to doing the calibration thing as to do it better I needed better tools, as Mech can testify too.

Firstly I might mention that using the tints was an experiment in replacing a filter at the projector, as many do and why I discuss this early on. However since then I have learnt alot more, about calibration, light properties, and I would argue for a flat spectral response now. I would also argue that using a filter can more problematic to the final result.

That aside.

Problems of adding tints and Aluminum, push pull push pull.

To get a flat response is difficult with measurement tools, and impossible without them.
Photo comparisons are for me just eye candy they prove little as there is too many varibles.



Mixes here are 50 mls of vivid white, 0.5ml and 1ml of Aluminum paste, 1 drop of yellow oxide and Red oxide.
You can see how things get out of shape pretty fast with small values.

Using a flat white as the Dulux vivid white I mentioned earlier as a base coat will arguably be better than a gloss finish base. I have recently found out that there is less TiO2 in gloss than flat; we want as much TiO2 as possible.
As I mentioned we need a third element to fix the spectrum when adding Aluminum or black. Al is harder to fix.

Quantities, I suggest using ml=grams as an aprox figure to work with.

Fisher, I use a Dulux Thomas Tallas 474, which is not spectrally flat btw. pushs blue, not as bad as Ali added though.
Start with the Dulux (flat) 620-04912 vivid white.

I am working on something better for the local market, keep an eye out.

Mech, do you realise how much work it will take shifting that lot...and if I moved them I would have to re write some of it as I have more knowledge know. Also I still have the panels, I would add spectral data which is more concrete.
Also all of that was created with a DIY probe, relying on a source which has since proved to be wildly out.
The basic observations are still valid though.

On the PJ issue, please post and Ill comment. Must have your calman working?

[mechman]

<^..^>Smokey Joe wrote:

Mech, do you realise how much work it will take shifting that lot...and if I moved them I would have to re write some of it as I have more knowledge know. Also I still have the panels, I would add spectral data which is more concrete.
Also all of that was created with a DIY probe, relying on a source which has since proved to be wildly out.
The basic observations are still valid though.

It was a pipe dream, I know! I'll break the sabbatical. But I'll try not to stray from the posted path into the realm of ridiculous!

<^..^>Smokey Joe wrote:

On the PJ issue, please post and Ill comment. Must have your calman working?

Yep! Derek sent me the link to the iso image. I installed the drivers from the cd and 'poof' - everything works fine. It was definitely a driver issue.

[fisher191]

<^..^>Smokey Joe wrote:

I am working on something better for the local market, keep an eye out.

Thanks Joe, when do you think you will have this ready?

[fisher191]

Hi again Joe (or any other Kiwi members),

I have been reading about the Black Widow and would like to try it. Do you know of an acrylic aluminium paint like the Henry 558 that I can find in New Zealand?

Thanks, Greg

[<^..^>Smokey Joe]

Fisher, No, most (98%) of options in NZ seem to be 2 pac or oil/spirit based when it comes to aluminum based roof paints.

Resene does an acylic aluminium and an enamel silver metalic, the aluminum crashes the spectrum when added to white, the silver metalic has too large a flake and sparkles. Been working on those without total success so far. Also been using a Ali paste, hard to get hold of btw as it is listed as hazardous goods as powder or paste. Still dispite having some it also crashes the spectrum.

The 558 contains more than ali, I think possibly bitumin? Its these extra bits that somehow control the spectrum.

What are you using now?

Oh and the answer to your previous Q......2 weeks....the standard time period for 4 weeks or more.
I used to fiddle with mixes it all the time, now I dabble on occasion.

To be realistic though there can be more to be gained from a decent calibration. Screens tend to deal in losses and compromises.

[fisher191]

Hi Joe, thanks for that.

I am using a 2400 x 1200 x 5mm high density mdf (I know thats a contradiction in terms) framed and braced with 20 x 50mm timber. I just sit it in front of the flat panel tv and sit the projector on the coffee table. I use felt for the borders and have wider, movable felt covered panels for the top and bottom so I can change the aspect ratio and hide the black bars. It is painted in a random white paint that would probably horrify you.

As part of a larger plan to reorganise, I want to rework the screen. I am going to make it a bit smaller, fixed at 2.35:1 and mask the bars at the projector (might get a lens later).

I have been considering a grey/silver as, although we usually watch at night, the room has light walls and ceiling, i.e. high in reflected light. I would prefer better blacks than I am getting now.

I like what I am reading about BW - this seems to be a good match for what I think I want.

[cynical2]

fisher191 wrote:

Hi Joe, thanks for that.

I am using a 2400 x 1200 x 5mm high density mdf (I know thats a contradiction in terms) framed and braced with 20 x 50mm timber. I just sit it in front of the flat panel tv and sit the projector on the coffee table. I use felt for the borders and have wider, movable felt covered panels for the top and bottom so I can change the aspect ratio and hide the black bars. It is painted in a random white paint that would probably horrify you.

As part of a larger plan to reorganise, I want to rework the screen. I am going to make it a bit smaller, fixed at 2.35:1 and mask the bars at the projector (might get a lens later).

I have been considering a grey/silver as, although we usually watch at night, the room has light walls and ceiling, i.e. high in reflected light. I would prefer better blacks than I am getting now.

I like what I am reading about BW - this seems to be a good match for what I think I want.

fisher, what do you mean by "mask the bars at the projector"? Do you mean you're going to mask the screen, or are you making something to actually do it at the projector?

[fisher191]

cynical2 wrote:

fisher, what do you mean by "mask the bars at the projector"? Do you mean you're going to mask the screen, or are you making something to actually do it at the projector?

The plan is to do it at the projector with a swing in mask. I have trialled a simple frame and while this was good for keeping the black bars off the screen, something a bit more sophisticated would be better for controlling reflected light (even though it is supposed to be black!).

I am thinking of installing the projector in the coffee table (it has a drawer through the middle like this one http://www.trademe.co.nz/Home-living...p-63879128.htm), but think of a hush box with a window.

[mechman]