Translucency Experiments

[mechman]

Data posted in third post.

[Harpmaker]

Did you do any incident readings mech? I would be interested in knowing how many Lux are hitting the panel surface at 100IRE and then how much is making it out the back. You would use the "sunken dome" on your meter for these readings, not the 1 degree spot.

[Prof.]

One thing I found very interesting is that even with two sprayed coats, you're still not getting any where near full reflectivity, and then suddenly on the third coat, you have it..
I wonder how many people have only ever given there screen just 2 sprayed coats of white paint, and not realized they aren't getting full reflectivity!

[Prof.]

As far as translucency goes..It looks like spraying is the only effective way of controlling the amount of translucency required..
Edit..Off course the problem with spraying a light coat onto mirror is that you then have severe hot-spotting..

[mechman]

Harpmaker wrote:

Did you do any incident readings mech? I would be interested in knowing how many Lux are hitting the panel surface at 100IRE and then how much is making it out the back. You would use the "sunken dome" on your meter for these readings, not the 1 degree spot.

Yes I did, but not in lux. I took them in foot lambert. 15fL was hitting the screen and outside of the 1 coat of sprayed, nothing would measure on the back side. For the 1 sprayed coat it was 1.1fL or about 12 lux. I think the spot meter readings were a bit more conclusive than the incident reading as I could actually get readings with it.

From the pictures it appeared that a lot of light was coming through the panels. But the readings show that what made it through has very little effect upon the overall picture. Even though it appears a lot of light may be getting through, it's not. Especially when you figure everyone is doing a minimum of two coats rolled or 6 sprayed.

It's also interesting to note that about 2-3fL are being absorbed by the paint. This verifies something I had thought earlier. It will be interesting to do this again with Black Widow or a neutral gray. I would guess that they would absorb an additional 1-2fL.

Another thing to note is that 6 sprayed coats equal roughly 2 rolled coats. Or 1 rolled coat per 6 sprayed. Doing the 50IRE readings also taught me that my spot meter will actually drop down to the thousandths in measurements.

That's what I get out of all of this anyways.

[mechman]

Prof. wrote:

One thing I found very interesting is that even with two sprayed coats, you're still not getting any where near full reflectivity, and then suddenly on the third coat, you have it..
I wonder how many people have only ever given there screen just 2 sprayed coats of white paint, and not realized they aren't getting full reflectivity!

I would hope no one! Unless of course they intended it that way. I've always thought that 6 coats was a minimum when spraying a screen unless you have some other plan for translucency and some sort of reflective backing.

Prof. wrote:

As far as translucency goes..It looks like spraying is the only effective way of controlling the amount of translucency required..
Edit..Off course the problem with spraying a light coat onto mirror is that you then have severe hot-spotting..

There's no doubt after this that if you're looking for even coverage and are trying to incorporate some sort of translucency, spraying is the way to go.

As for the mirror, I cannot tell if they hot spot or not. And my initial findings show absolutely no advantage to using a mirror at all. My reference hardboard panel was as bright or brighter than all of my mirror tiles. And I wasn't expecting that! That's why I asked Harp to double check my findings. And it's also why I have yet to post those results.

[Prof.]

mechman wrote:

There's no doubt after this that if you're looking for even coverage and are trying to incorporate some sort of translucency, spraying is the way to go.

As for the mirror, I cannot tell if they hot spot or not. And my initial findings show absolutely no advantage to using a mirror at all. My reference hardboard panel was as bright or brighter than all of my mirror tiles. And I wasn't expecting that! That's why I asked Harp to double check my findings. And it's also why I have yet to post those results.

The translucency result doesn't surprise me, and just confirms what I said in my earlier post..
Plain white paint diluted for spraying is still too opaque to provide any sort of real translucency..and to thin it any further would only create spraying problems..

To obtain a controlled application of a translucent white paint, I believe it needs to be mixed into a clear medium of similar viscosity to the paint itself..Then you can add as much or as little as you want to obtain a translucent coat..even to the point of being able to roll it on, as I did with my screen..