household paint and mediums

[custard]

i mixed up a sample of S1500-n with the medium and AAA-M. S1500 being the the household paint i used previously for an 8:1 AAA-M panel at about N8.2.

the spectro readings for the new sample are promising:



hopefully i have enough AAA-M to paint a panel. as the readings are quite similar to the previous panel we should get a decent comparison.

[custard]

i had enough AAA-M to paint a panel.

LHS panel - slightly color corrected s1500n, Lab 83.41 -0.88 0.65, RGB 205 207 205

Middle panel - 4:4:1 s1500n:medium:AAA-M, Lab 81.73 -0.27 0.46, RGB 202 202 201

RHS panel - 8:1 s1500n:AAA-M, Lab 81.98 -0.28 0.70, RGB 203 203 201


with room lighting:



with flash:



black white bars:



horizontal grey bars:




i have a feeling that the medium may be lowering the gloss level further on the household paint as the flash image shows the panel containing the medium is significantly darker than the other two.

any thoughts??

[Harpmaker]

Very interesting Custy. I know I say that a lot, but I mean it.

The fluid matte medium seems to be having a darkening effect on the mix; that is the opposite of the effect we were hoping for. To top it off, it's not a physical effect (like adding gray to the mix), but more a suppression of the reflectivity of the mix. That is a head-scratcher! On the plus side, we may need this effect when we go to using all artist paints that might have gloss to them.

[custard]

i've been abit sidetracked at the moment with regards to further testing.
thinking aloud i think the only other ingredient i can change is where s1500n is bought from. this base was bought from dulux (i seem to recall people have had problems with dulux paints and AAA-F).

in the near future i will buy some s1500n from the same outlet that mixes the ukbw clone (s0907) and check if this improves matters with the 8:1 mix.

for now i will save the fluid matte medium for use with the artist paints to help reduce that gloss level as you have recommended Harp.

at the moment i have been trying to work out how light i can go with a 5:1 mix with AAA-F. preliminary readings are around 199 for RGB(about N8). i will keep you informed.

[custard]

well i slightly fudged up my tests of the 5:1 AAA:F

my first sample mix was 1ml:4ml:1ml:0.1ml for the paint listed below and resulted in a reading of 199,200,200 or so. this mix was prone to being slightly inaccurate even though i used 5ml syringes for titration.

the mix i created utilised 1 part AAA-F, 4 parts lumitec, i part crown paint (this base was initially tested for use as the base in a 3:1 UKBW mix) and 0.1 parts diluted artist yellow (for color correction).


the mix got me excited and i decided to mix enough for a panel. this is where i seemed to have gone slightly wayward.
the mix was watered down about 20% and some of it was used for a further sample.
the reading on this new sample was about 200,201,203 - a blue push.
even more disturbing was that the reading for the resultant panel using the same mix after 3 coats gave a reading of 195,196, 199.(about N7.9)
maybe the error was in the preparation of the panel. i used a panel which was initially painted a slightly darker grey (n7.8) and then painted over with one coat of white paint only.

i decided not to tabulate any accurate readings as they were off anyway.

testing of the panel was quite interesting.
i set the camera to take black and white pictures to allow for the blue push.
for comparison i used an N8.34 matt grey panel.
the projector was moved from its original upside down below ceiling postion to a conventional table position. note that the optoma hd65 has a built in offset.

in room lighting the N8.34 on the left is brighter as expected:

i found that this was also true with the flash but i am having difficulty locating the image


a 100% white field with the camera near to the projector lens


but this last image gives me some hope. 100% white field taken from a standing postion


looking at the above results i am thinking the the 5:1 panel is exhibiting signs of gain and a possibly a narrowing of the viewing angle??

i have also started another small experiment. the use of pure Autoair aluminum with an overcoat of fluid matte medium.

for now i just used a brush to paint thick samples of AAA over which i will paint a layer of matte mediium.

i will get round to those artist paints at some point aswell

[custard]

i've just realised my mistake. the amount of yellow should have been 0.2 parts not 0.1

[Harpmaker]

I think aluminum just likes to mess with our heads.

I have no idea why your latest AAA-F panel is brighter vertically OFF-axis than on-axis, unless it would be that the angle you are viewing the panel from standing up is closer to the inverse of the angle the table-mounted PJ is shooting at.

This might be something that should be looked into... unless the screen in use is of a retroreflective nature (ie. glass beads or mirrors are used), the PJ should be mounted such that the viewing angle is as close to the inverse of the projection angle as possible. This would ensure maximum gain from the screen.

[custard]

i will test the panels with the projector in the ceiling position. if i am understanding correctly the gain should increase in the sitting position with that setup.

i rememeber you spoke to a sales assistant who sold lumitec paint to you. did he not say that it may contain glass beads ?(they are not apparent to the naked eye)

my other theory is that the lumitec may have more sheen than other matt paints, it says rich matt on the can.

i will put the AAA-M panels up recheck them again aswell.

that aluminium is a right head messer.
and this color correction malarkey is not far behind

[Harpmaker]

custard wrote:

i will test the panels with the projector in the ceiling position. if i am understanding correctly the gain should increase in the sitting position with that setup.

Yep, that's my thinking. I'm now wondering if this is the reason mech wasn't seeing the same results from his AAA-M tests as I was. He has a ceiling mounted PJ (I think) and mine is setting on a bench. My standing "eye level" (and the level I take screen photos at) would just about be vertically inversely angular to the PJ beam.

i rememeber you spoke to a sales assistant who sold lumitec paint to you. did he not say that it may contain glass beads ?(they are not apparent to the naked eye)

Yes, the LumiTec paints have microscopic glass beads in them. The pamphlet shows electron microscope photos of them. I don't think these paints are retroreflective; at least not anywhere near the level of road or sign paints.

my other theory is that the lumitec may have more sheen than other matt paints, it says rich matt on the can.

This could well be the case. It's still my thinking that different countries have different standards that the paints sold in them must meet. This is one of the main reasons I would like to start using artist paints as bases as well as coloring tints and reflective additives. I could be wrong, but I think the Golden or Liquitex paints you buy in the UK are the same as the ones I buy in the US.

i will put the AAA-M panels up recheck them again aswell.

that aluminium is a right head messer.
and this color correction malarkey is not far behind

Yep, it seems to defy logic at times.

Something I have noticed is that spectral curves tend to cancel each other out. We can use this fact to color correct paint. I don't have it down to a science yet though..., but I am sure X-rite does and in fact it's the way their paint matching programs work.

The hardest thing for me to do was start thinking subtractively. You never really add a color to a paint mix, you rather subtract the opposite color.

[custard]

well harp i have some further interesting observations to report.

i dont think i am seeing the increase in reflectivity with my 8:1 AAA-M panel using the same testing parameters as above.

but i do think the 4:4:1, matte medium:base:AAA-M is showing the trait. only problem is that when viewing a 100% white field i can see some bright flecks from over 2 metres away.

i'll try and get some pics up at some point after further testing.

[Harpmaker]

custard wrote:

well harp i have some further interesting observations to report.

i dont think i am seeing the increase in reflectivity with my 8:1 AAA-M panel using the same testing parameters as above.

OK, please refresh my memory; did AAA-F at 4:1 work with this base?

but i do think the 4:4:1, matte medium:base:AAA-M is showing the trait. only problem is that when viewing a 100% white field i can see some bright flecks from over 2 metres away.

i'll try and get some pics up at some point after further testing.

That is interesting! So it seems that when the base gets translucent enough for the aluminum to work, the "grain size" of the aluminum particles becomes a problem and specularity is seen.

Now the questions that come to mind are:

1. Would using less matte medium in the mix solve the specularity problem while still allowing the AAA-M to produce gain?

2. Would AAA-F work in the 4:4:1 mix? (We'll worry about color correction later)

[custard]

Harpmaker wrote:

OK, please refresh my memory; did AAA-F at 4:1 work with this base?

i dont think i ever tested that but i'm pretty sure it will result in a severe blue push as the base is warm grey about n8.5

That is interesting! So it seems that when the base gets translucent enough for the aluminum to work, the "grain size" of the aluminum particles becomes a problem and specularity is seen.

Now the questions that come to mind are:

1. Would using less matte medium in the mix solve the specularity problem while still allowing the AAA-M to produce gain?

ok, i know what you are getting at....
i'll have to order some more AAA-M. the amount i have left is not enough for another panel

2. Would AAA-F work in the 4:4:1 mix? (We'll worry about color correction later)

that is something i can test although comparison with the AAA-M panels may not be ideal as they are lighter. but i can compare to my original UKBW wall.

looking at what mech has posted on the gain readings for BW it seems to imply that any gain is diffuse not specular.
my impression was that the above results were showing angular gain (specular)

it will be interesting to compare his BW readings to an equivalent matte N7.5 (veil)



completely off topic - we are using Bruce's RGB while Mech is using sRGB (Babel). i have noticed that the sRGB readings at D65 are slighty higher than Bruce RGB. maybe this is why your VUPE readings were slightly lower than mechs. the readings change more as we get lighter.
i do still think my Luminance readings are slightly lower than mechs but i can verify everything if we reach a point of needing to (i'll edit this paragraph out later as it is not relevant to this topic)

[custard]

i received my charger for the laptop today so i was able to project some images. they show the increase in angular reflectivity with the panel that has the medium as part of the formula.

the panels:

LHS panel - 4:4:1 s1500n:medium:AAA-M, Lab 81.73 -0.27 0.46, RGB 202 202 201

Middle panel - slightly color corrected s1500n, Lab 83.41 -0.88 0.65, RGB 205 207 205

RHS panel - 8:1 s1500n:AAA-M, Lab 81.98 -0.28 0.70, RGB 203 203 201


photos taken in black and white with projector on a low table.

with ambient room lighting:



100% white field with camera near projector:



100% white field with camera in standing position:



also note that when the projector is placed in the ceiling position the increase in reflectivity is seen in the sitting position.

[Harpmaker]

custard wrote:

completely off topic - we are using Bruce's RGB while Mech is using sRGB (Babel). i have noticed that the sRGB readings at D65 are slighty higher than Bruce RGB. maybe this is why your VUPE readings were slightly lower than mechs. the readings change more as we get lighter.
i do still think my Luminance readings are slightly lower than mechs but i can verify everything if we reach a point of needing to (i'll edit this paragraph out later as it is not relevant to this topic)

I thought I had responded to this, but if I did I can't find it. I've had a very nasty cold the last 10 days... can't seem to shake the sucker.

On Bruce's calculator spreadsheet, use cells L, M & N 41 to get sRGB values; don't use the Bruce RGB values in L, M & N 31. It's my understanding that RGB values are really not that much use since they are device-dependent.

Yeah, projector angle seems to be more important that I thought it would be. That makes sense though, it's the nature of reflection off any surface that is not a perfect diffuser (and very little is).

[custard]

I've had a very nasty cold the last 10 days... can't seem to shake the sucker.

lets hope the it does not ruin the festivities

On Bruce's calculator spreadsheet, use cells L, M & N 41 to get sRGB values; don't use the Bruce RGB values in L, M & N 31. It's my understanding that RGB values are really not that much use since they are device-dependent.

gotcha!

Yeah, projector angle seems to be more important that I thought it would be. That makes sense though, it's the nature of reflection off any surface that is not a perfect diffuser (and very little is).

so the 5:1 AAA-F panel, and the AAA-M panel with the medium is showing some signs of the gain we are striving to achieve.
i will have a go at altering the AAA-M/medium ratios in the new year in the hope of making the bright flecks disappear.

more to follow on the 5:1 AAA-F very soon aswell!

AND if anyone else has any ideas/thoughts that they want to discuss please don't hesitate - we don't bite.

[mechman]

Correct me if I'm wrong here but aren't we looking at retro-reflective gain? It's only seen sitting down, not standing up. How did you achieve that with paint custy? I can attest to seeing nothing sitting or standing in my AAA-M trials. But my pj is ceiling mounted, as harp said.

This is a clear matte medium you're using right custy?

Excuse me if this has all been hashed out already, it's my first time reading this! And we all know how poorly I do that most of the times!

mech

[custard]

mechman wrote:

Correct me if I'm wrong here but aren't we looking at retro-reflective gain? It's only seen sitting down, not standing up. How did you achieve that with paint custy? I can attest to seeing nothing sitting or standing in my AAA-M trials. But my pj is ceiling mounted, as harp said.

This is a clear matte medium you're using right custy?

Excuse me if this has all been hashed out already, it's my first time reading this! And we all know how poorly I do that most of the times!

mech

no worries mech,

definitely not retro-reflective otherwise the gain woul be seen when the photo is taken near the source of the light i.e near the projector.

to repeat: when projector is under ceiling the gain is seen when sitting down. when projector is located on the table the gain is seen standing up.

you also need to note that the optoma HD65 employs an offset.


my 8:1 AAA-M panel does not exhibit these properties - same as yours.

the 4:4:1 AAA-M panel with golden fluid matte medium (and the 5:1 AAA-F panel) do exhibit these properties.

[mechman]

I guess i shoulda asked where your pj was mounted first!

mech

[custard]

i had a second attempt at mixing up the lumitec panel (5:1 AAA-F) discussed earlier in the thread.

the variance in readings between the sample and the panel occurred again

i made sure i primed the panel with three coats of white paint.
the mix i used was diluted about 25% and 4 coats were applied to the panel. the remainder of the paint was placed on a piece of card for the sample reading.

three different paints in the base mix - 4 lumitec, 1 crown base, 0.15 parts yellow



the sample reading



the panel reading


the drop in luminance from the sample to the panel and the increased blue push has baffled me.
do you guys think this may be caused by some sinking of aluminium in the sample?

i havent seen this much difference of readings between my other aluminium samples and their corresponding panels...

[custard]

Harpmaker wrote:

Your 5:5:1 base:medium:AAA-F mix come out to 9.09% AAA-F.

Don't judge anything until the sample has dried at least 6 hours, and I prefer to wait 24 hours before taking a spectro reading.

I think we all agree that the aluminum below the screen surface is active and making the mix more translucent will only increase the effect. I think we're on the right track increasing mix translucency. The LumiTec might be helping a little, but I think the beads it contains are so small that what you are seeing is due to a more translucent mix; but I could be wrong.

wbassett wrote:

First things first though... let's see how the matte medium works at making things more translucent and what an image looks like on some test panels.

here are the preliminary test panel pics it has been drying/curing for about 14 hours.

on the left is the matte grey N8.34
in the middle is the medium:base:AAA-F 5:5:1 (will confirm reading later but is about N8.17 from uncured reading last night)
on the right is the medium:base:AAA-M 4:4:1 N8.17

black and white pics, projector on low table top. slight amounts of ambient light.

100% white field, camera by projector. retroreflective gain postion


100% white field, camera about middle of screen


100% white field, camera in standing position (equal to height of panels). angular gain position


black white bars standing position


zoom of grey scale. cant remember camera position

[custard]

custard wrote:

yep, i'm of the same opinion.

i had placed that panel in the middle so that we could compare to two panels.

give me an hour or two and i will swap the panels around. from what i remenber last night movement of the panel to the side did not have too much of a detrimental effect.

i have rushed these images through so the quality may not be the best.

5:5:1 AAA-F on the left, matt grey middle, 4:4:1 AAA-M on the right.

room lighting


camera by projector


camera middle of panels


camera at height of top end of panels

[Harpmaker]

It should be noted that the photos in the post above show how important it is to orient your projector to your screen type.

Screens that use glass beads (like the Da-Lite High Power) are retro-reflective; these types of screens will show the brightest image with the viewer (or camera) is at the same angle to the screen as the projector.

Screens that are specular (or angular) reflective (most DIY mixes) will show the brightest image when the viewer (or camera) is at the inverse angle to the screen as the projector, meaning that if you intend on viewing your screen setting down (like most of us ) you would want to mount the PJ on the ceiling.

I'll add some drawings to demonstrate these when time permits.

[custard]

thats slightly over color corrected.

the problem with trying to use high pigment paints means that even being accurate to ml can still cause variation.
this is one of the reasons we try to find a suitable base that does not need color correction.

we donot advise the the addiition of high chroma colors such as red,blue,green,yellow to diy mixes as it becomes very difficult to keep the mix neutral.
we'll do the hardwork so you dont have to

[mechman]

Harpmaker wrote:

Screens that are specular (or angular) reflective (most DIY mixes) will show the brightest image when the viewer (or camera) is at the inverse angle to the screen as the projector, meaning that if you intend on viewing your screen setting down (like most of us ) you would want to mount the PJ on the ceiling.

I'll add some drawings to demonstrate these when time permits.

There's one here in this post.

mech

[Harpmaker]

mechman wrote:

There's one here in this post.

mech

Thanks mech, I forgot that was there.

Here is a link to a page by Da-Lite that talks about retro-reflective and specular reflective screens that some might want to take a gander at: http://www.rentcom.com/wpapers/dalite/vol17.html

It's a bit "dry", but lots of info is there. One of things that was illuminating was the last statement, "These are the only things a projection screen can do: Reflect, Scatter, or Refract."