Pearl Clear Coat Trials - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 104 Old 07-14-07, 11:02 AM Thread Starter
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Re: Pearl Clear Coat Trials

The first trial panels have been clear coated and now can dry until after the boss goes to bed tonight.

Panel #1
Base Layer: Behr UPW Flat Latex #1050 (0/6/0LB+0/3/0YO)
Top Coat: 2oz. each of Decoart & Folkart Pearlizing Medium / Quart Behr Poly #780

Panel #2
Base Layer: Behr UPW Flat Latex #1050 (0/6/0LB+0/3/0YO)
2nd Layer: 4oz. Silver Metallic Flake medium / Quart Behr Faux Glaze
Top Coat: 2oz. each of Decoart & Folkart Pearlizing Medium / Quart Behr Poly #780

Panel #3
Base Layer: Behr UPW Flat Enamel #1850 (0/6/0LB+0/3/0YO)
Clear Coat: 2oz. each of Decoart & Folkart Pearlizing Medium / Quart Behr Poly #780

Panel #4
Base Layer: Behr Exterior Primer #436 (0/5/0LB+0/2/0YO ~match)
Clear Coat: 2oz. each of Decoart & Folkart Pearlizing Medium / Quart Behr Poly #780
Tonight we will see what difference the base layer makes and also see what effect the intermediate silver flake layer has on gain and viewing cone.

The Fauz Glaze it very nice to apply. It also remains workable for quite a while so down rolling it with the 6" trim roller was no problem. I like to apply paint with the white fuzzy roller because you can get it on the screen and spread out quickly. Then I smooth out the current strip and back to the previous one, followed by down rolling. Both the glaze and the poly will level out quite well so any texture will be from the underlying base coat.

Next up will be two panels with the exact same base layer. One will have 2 coats of 2xPearl (Folkart) and the other will have 2 coats of 2xPearl (Decoart). This is to see what difference there is between the two products. I will speculate the Decoart will have a bit more gain and a slightly reduced viewing cone compared to te Folkart sample.

Now we watch the paint dry.
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post #12 of 104 Old 07-14-07, 12:56 PM
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Re: Pearl Clear Coat Trials

Quote:
mechman wrote: View Post
Also, in the photos above in post 1, it appears that the topcoats brighten the image while dulling the contrast. Is that what you see? The darks look darker in the non-topcoated. Might want to do some trials with varying degrees of ambient light... just pondering.
The darks are darker in a non topcoated screen. A pearl top coated base coat will have gain. Therefore, raising white level and also raising black level. Off axis would be even worse because white levels are now lowered.

I like topcoats for their "3D effect" and nice colour saturation. But there are always tradeoffs. And that would be higher black levels.

What I suspect is that the lack of "gray" in the topcoat does this. I am currently experimenting with a small amount of "gray" in the topcoat in the hopes to maintain black while increasing white. Sounds contradictory, but we'll see how it goes.
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post #13 of 104 Old 07-14-07, 03:22 PM Thread Starter
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Re: Pearl Clear Coat Trials

I just noticed that Sample #3 has visible roller tracks. I can't tell if they are in the Faux Glaze layer or the poly top coat. When I hold it up to the light I can't see them. If this does prove to be a worthwhile multi-layer solution I will have to work out the application issues.

All the other sample panels look good and uniform. That would suggest it is in the faux glaze layer but it's hard to tell.
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post #14 of 104 Old 07-14-07, 11:11 PM Thread Starter
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Re: Pearl Clear Coat Trials

The Pearl Clear Coat trials begin:

We will start with some camera flash photos. This will give an indication of the tendency to hot spot.


Lets start with a simple matte UPW #1850 panel:

There is no apparent warm spot. The shade seems pretty uniform top to bottom.


Now we will see what a flat gray with a polyurethane only clear coat looks like:

Again the brightness is fairly uniform from top to bottom.


Now we will look at what the camera flash does to a flat UPW #1050 with a 2xPearl clear coat:

The flash spot is quite evident in this photo. It is also evident that I managed to get some streaks in the pearl clear coat.


This is the Flat Enamel \ 2xPearl Clear Coat Sample:

There definitely appears to be a warm spot in this sample.


The Behr Exterior Primer #436 \ 2xPearl Clear Coat:

This sample too appears to be producing a warm spot.

Behr UPW #1050 \ Silver Glaze \ 2xPearl Clear Coat:

Again there is a warm spot and the streaks are quite bad in this sample.


Setup Info:

The camera was in auto mode. I used a tripod. The camera was approximately 8 feet away from the screen. I'm not sure if the camera should be this close or if it should have been closer to the projector. I will repeat these photos with the camera near the projector.
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post #15 of 104 Old 07-15-07, 02:22 AM Thread Starter
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Re: Pearl Clear Coat Trials

I repeated the camera flash tests and also did the projected white light tests

Here is the Behr UPW Flat Enamel #1850:
12ft Camera Flash <==> White Light

As expected there is no sign of hot spotting.

Flat Gray Latex \ B780 Clear Coat:
12ft Camera Flash <==> White Light

Again no sign of hot spotting.

Behr UPW Flat Latex #1050 \ 2xPearl Clear Coat
12ft Camera Flash <==> White Light

There appears to be a tendency to warm spot.

Behr UPW Flat Enamel #1850 \ 2xPearl Clear Coat:
12ft Camera Flash <==> White Light

While there is some tendency to hot spot the #1850\2xPearl seems to be slightly less likely to hot spot than the #1050\2xPearl.

Behr Exterior Primer #436 \ 2xPearl Clear Coat:
12ft Camera Flash <==> White Light

There does not seem to be anymore tendancy to hot spot than the #150 \ 2xPearl.

Behr UPW #1050 \ Silver Glaze \ 2xPearl
12ft Camera Flash <==> White Light

The streaks are quite evident, however the tendency to hot spot seems to have remained constant for all the 2xPearl Clear Coated samples..
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post #16 of 104 Old 07-15-07, 02:26 AM Thread Starter
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Re: Pearl Clear Coat Trials

Just a quick comment at this point:

I keep thinking I was too greedy. I should have only tried 1xPearl. It would be better to lower the Pearl per coat and apply more coats. I still think the Faux Glaze is a good choice for the intermediate layers. It is thicker and dries very clear. The additional matte poly top coats eliminate any sheen issues from the glaze.

As benven pointed out the mediums have quite a bit of gloss. Reducing the amount added to the poly will reduce the surface sheen.
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post #17 of 104 Old 07-15-07, 10:12 AM Thread Starter
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Re: Pearl Clear Coat Trials

Ambient Light Tolerance

Mechman observed that the Pearl Clea Coats seemed to not only brighten the whites but also lighten the blacks. This of course is not a desirable effect. I had not observed this in the photos nor did I recall noticing it when doing previous trials. In order to make the lightening of blacks more noticeable I took the following photos with as much ambient light as I could turn on.

First lets see what the Flat Enamel #1850(matte) UPW
and the UPW #1050 with a poly clear coat do in these high ambient light conditions:

Both samples seem to be very similar to my retractable screen.


Now lets see what happens to the blacks when there is a 2xPearl clear coat:

The blacks definitely are suffering in these high ambient light conditions.


Then there is the UPW #1050 \ Silver Glaze \ 2xPearl sample:

As expected the blacks on this sample also suffer in high ambient light conditions.


So as Benven pointed out everything is a compromise. Increased gain will cost you some ambient light performance, if that ambient light is coming from the projector end of the room.
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post #18 of 104 Old 07-15-07, 10:31 AM Thread Starter
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Re: Pearl Clear Coat Trials

Off Axis Performance

Another compromise when boosting on axis gain is that off axis gain will usually be reduced. This of course is what is meant when people talk about the viewing cone being reduced. As a general rule I look for a poly clear coated sample to match performance with a matte sample at about 45 degrees. This is only a crude measurement but all we really have for the moment. In the case of a pearl clear coated sample I would hope it too would match performance with the matte screen at about 45 degrees. That is probably a bit optimistic. Past gain curve measurements showed that the poly clear coated samples crossed over the matte samples at around 30 degrees.

Here are photos taken from approximately 45 degrees off axis:

Here are our reference matte gray and poly clear coated gray samples:

As I expected the off axis gain of these two samples is very similar to my retractable screen.


Now lets see how well the Pearl Clear Coated samples perform off axis:

As one might expect they are not quite as bright as the retractable screen surface. Not too bad though.


Finally our 4 layer Silver Glaze & Pearl Clear Coat sample:

It appears to be similar to the other Pearl Clear Coated samples.


The concern with narrowing the viewing cone is most significant if the the variation in brightness is apparent when sitting within the expected audience area. In other words if you are sitting in one of your desired viewing locations that is at the extreme of the viewing angle in your setup, will you see a variation in brightness from the nearest side of the screen to the farthest. This is the real concern, not what the image looks like to someone way off to the side in the next room looking in through a side door way.

I cannot say at this time if that is an issue or not. I have been trying to think of a method to look at this without making up an entire screen. I think if I take a photo of the screen with white light on it and place a sample panel at the 4 locations across the screen, then it may be possible to determine. I would have to make sure the brightness of the background screen remained constant over the 4 photos. Then you could compare the 4 photos to see if the brightness of the sample varied from position to position. I'll have to give this a try. Not being any great photographer I would be inclined to adjust the brightness in Photoshop to get the backgrounds to match.

In the meantime I have started to prepare the next samples. It is two identical base coat samples. One will get 2xPearl-Folkart 2 coats, and the other will get xPearl-Decoart 2 coats. I am pretty sure already from applying the Decoart pearl clear coat that it is more silvery looking than the Folkart.

The trial to follow that will be a matte white reference compared to the same matte white base coat with 2 coats of 1xSilver (Delta Silver Metallic). This is to determine if we could apply such a silver (gray) clear coat to a white base and increase the black level performance and maintain the whites or even boost them. The really test will be to see if I can apply this uniformly.
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post #19 of 104 Old 07-15-07, 12:30 PM
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Re: Pearl Clear Coat Trials

Great work tiddler!

I have often wondered why certain other very famous paint mixes are so popular. One look at this thread would really open up some eyes. Those craft store paints add nothing but gloss. And for those famous mixes that are predominantly craft store paints, they do hotspot, have poor off axis performance, and have poor colour balance. Hopefully, I don't get raked over th coals like I would in another popular forum where those very famous paint mixes rule the roost.

This is why I have been advocating the use of metallic powders instead of metallic paints. You can control the amount of gray or pearl in amix and try to maintian a reasonable balance of gain, cone, and colour. Can't do that with craft paints.
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post #20 of 104 Old 07-15-07, 01:32 PM Thread Starter
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Re: Pearl Clear Coat Trials

Quote:
benven wrote: View Post
Those craft store paints add nothing but gloss.

This is why I have been advocating the use of metallic powders instead of metallic paints. You can control the amount of gray or pearl in amix and try to maintain a reasonable balance of gain, cone, and colour. Can't do that with craft paints.
I don't think I would jump to that conclusion already. I would imagine that the pearlizing medium alone does have a gloss when dry. Keep in mind though I am only adding 2 or 4oz. od the medium to 32oz. of Behr Matte Poly. Yes it will add some sheen to the poly but the gain I am seeing appears to be more a result of the metallic or pearl flakes. If it wer sheen alone then there would be terrible hot spotting from the projected light the way the Behr Eggshell hot spotted.

You may be looking at the first set of photos where the camera flash was used too close (8ft) to the samples. Once I moved the camera back closer to the projector position things looked much more reasonable.

Using the projector we don't see the hot spotting problem:

Curiously it is the primer that seems to be not only the brightest but also to have the most uniform brightness top to bottom. I was expecting it to be the worst of the three for base paints for this warm spotting behavior.


With the camera flash close to the projector position the hot spotting is not predominant either:



Using the camera flash about 8 feet from the panels does cause a noticable hot spot but I don't think it is realistic:



At the moment my suspicion is that the Decoart has flakes that are more silvery than pearly. That is probably where the hot spotting is coming from. The next samples that will compare the Folkart Pearlizing Medium to the Decoart Pearlizing Medium in 2xPearl Clear Coats will tell a lot about the type of flakes. Again will also say that if I were pressed to produce screen of this type right now, I would opt for only a 1xPearl and more coats utilizing the Faux Glaze for the first two clear coats and the matte poly for the final two clear coats. Another approach using the same ingredients would be to mix 2oz. of Folkart Pearlizing Medium, 2oz. of Decoart Pearlizing Medium, a quart of Faux Glaze, and half a quart of the matte poly. This would then be applied as three coats of 1.5xPearl Clear Coat. The remaining pure matte poly would be appled as a top coat to kill any gloss. Hmmm . . . that sounds like a reasonable plan. But lets see what the difference between the two pearlizing medium is before we jump to any conclusions.

I do however agree that for the best results one would use high quality ingredients and keep them separate. By using craft store pearlizing medium you get both flakes and clear medium in the bottle. If the medium adds gloss then you are limited as to how much pearl flake you can add. By using pearl powders you first of all can chose the flake size and secondly you have total control over the concentration of flakes without effecting the gloss or other characteristics.

I am hopeful that once you feel more comfortable posting here you will present some of your work to the members here. I am trying to cover the Average Joe, pickup some stuff on the way home and make a screen over the weekend demographic. I think this represents a large number of people new to the idea of making a front projection screen. Like me many people find themselves with a projector and when they started to look into a suitable screen the price of the project suddenly doubles. My goal is to find a few solutions for them, that will tied them over until they are prepared to either buy a good screen, implement a laminate screen, or try a more advanced mix like the solutions that you have explored. I know there are many here that would be interested in your work and also in any knowledge you are willing to pass on regarding spray painting.

Last edited by Tiddler; 07-15-07 at 01:40 PM.
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