household paint and mediums - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 26 Old 12-06-08, 01:45 AM Thread Starter
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household paint and mediums

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.
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post #2 of 26 Old 12-07-08, 02:08 PM Thread Starter
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Re: household paint and mediums

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??
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post #3 of 26 Old 12-07-08, 05:47 PM
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Re: household paint and mediums

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.
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post #4 of 26 Old 12-10-08, 11:17 AM Thread Starter
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Re: household paint and mediums

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.
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post #5 of 26 Old 12-13-08, 03:45 PM Thread Starter
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Re: household paint and mediums

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

Last edited by custard; 12-14-08 at 10:52 AM.
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post #6 of 26 Old 12-14-08, 10:48 AM Thread Starter
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Re: household paint and mediums

i've just realised my mistake. the amount of yellow should have been 0.2 parts not 0.1
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post #7 of 26 Old 12-14-08, 02:08 PM
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Re: household paint and mediums

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.
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post #8 of 26 Old 12-14-08, 03:31 PM Thread Starter
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Re: household paint and mediums

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
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post #9 of 26 Old 12-14-08, 06:22 PM
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Re: household paint and mediums

Quote:
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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.

Quote:
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.

Quote:
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.

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


Quote:
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.
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post #10 of 26 Old 12-16-08, 01:13 PM Thread Starter
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Re: household paint and mediums

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.
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