The Official Polyurethane Top Coat (PTC) Thread

[1Time]

A polyureathane that has been recently discussed for use as a top coat is the following, which is sold at Home Depot:

BEHR PREMIUM PLUS WITH STYLE® Crystal Clear Water Based Polyurethane No. 780 (http://www.behr.com/behrx/act/view/products_detail?prodGroupId=21&catName=Faux%2FDecorative+Finishes&catId=18).

Q: Why or why not use a polyurethane top coat (PTC)?

A: You may prefer how it looks on your paintable DIY screen, and it will help protect your screen. And then again you may not prefer how it looks or deem it desirable to add this protection. Answering this question to your satisfaction is the purpose of this thread.

Q: What DIY screens could benefit from a polyurethane top coat (PTC)?

A: Potentially all paintable DIY screens could be improved with the use of a PTC. Whether you would find such a top coat preferrable may be a matter of personal preference and/or desire to protect the surface of your DIY screen. Answering this question to your satisfaction is also the purpose of this thread.

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I hope to soon try out a PTC on a couple of paintable surfaces to see how well I like it. I will post back with some screenshots and my impressions after testing.

I invite all to discuss / post your impressions of your PTC. Please also post your projector make and model and a description of your DIY screen. Thanks

[georgeorwell]

This thread is a great idea! Great pics in your link, I like how you have everything so clearly labeled. Of course I look at those pics and wonder why the hell I have a SS painted screen.

[1Time]

This thread is a great idea! Great pics in your link, I like how you have everything so clearly labeled. Of course I look at those pics and wonder why the hell I have a SS painted screen.

Thank georgeorwell. Perhaps you have a SS painted screen so you can now give it a PTC... lol. Those pics in my gallery are fairly dated. I look forward to soon adding more meaningful ones. :)

[bruce can]

This thread is a great idea! Great pics in your link, I like how you have everything so clearly labeled. Of course I look at those pics and wonder why the hell I have a SS painted screen.

Your screen probably has the most potential for improvement by putting a topcoat on than most here ,especially if you rolled your screen.

Bruce

[georgeorwell]

I got the Behr poly last night. I'm doing a fresh, smooth repaint of the SS first. I'll take some pics. Then I'll put on the PTC and take pics of the same images. Hopefully by Monday I'll have some ready to post.

[1Time]

I got the Behr poly last night. I'm doing a fresh, smooth repaint of the SS first. I'll take some pics. Then I'll put on the PTC and take pics of the same images. Hopefully by Monday I'll have some ready to post.

georgeorwell, IF your SS screen is not already very smooth, you may want to wet-sand it before rolling another coat of SS. And, IF you add another coat of SS, I suggest you consider letting it cure for a few days up to a week before adding the PTC. Perhaps one of these professional painters around here knows better than me on this and will advise.

The link to the Behr poly in post #1 describes the type of roller Behr recommends. I would think the same roller could be used for the SS.

--------------------------------------

Tiddler, thanks for all your poly pioneering. I'm sure other matte polys would work as well and maybe even better somehow. I linked Behr's poly in post #1 since it's been discussed recently and successfully used as a PTC.

[bruce can]

I would give the paint a good 24 hours to dry completely before applying the poly. You don't want the paint dissolving into the poly top coat.

Actually all the paint needs to do is surface dry , not cure to topcoat with acrylic, it is desirable to paint when the previous coat is only just dry and not cured for adhesion .

If you are not going to repaint the grey I would not sand it before top coating, wet or dry . BUT If you have to, just do a very light knock down with very fine paper.

With the poly top coat the speed you roll is important go slower and you will get a lot less bubbles, which will show up later as texture .

Acrylic Poly finishes do a lot better with spraying or brushing than rollers. If I was rolling I would thin slightly .

Bruce

[georgeorwell]

Great info...thanks! I'm off to Home Depot to get a few more materials.

[bruce can]

Ok here is what you should use if you really want a smooth finish with a roller using poly acrylic finishes .

Those finishes have a faster open time than a lot of paints you guys are used to using, so for a cheap solution for using rollers and these finishes you might want to try these products .

http://www.misterart.com/store/view/001/group_id/2272/LIQUITEX-Acrylic-Flow-Aid.htm
http://www.misterart.com/store/view/001/group_id/2050/Liquitex-Slow-Dri-Fluid-Retarder.htm


You do not have to use these brands but they will help in getting a smoother finish with these clear finishes ESPECIALLY if you roll .

Even a DIYer should be able to spring an extra five bucks to have the best image possible :)

Bruce

[georgeorwell]

OK, I've got some premliminary test pics. I don't have any of SS vs SS w/PTC, but I do have SS w/PTC vs. a white screen. Hate to ask such a noob question....but how do I post pics in the body of my posting?

[prof55]

OK, I've got some premliminary test pics. I don't have any of SS vs SS w/PTC, but I do have SS w/PTC vs. a white screen. Hate to ask such a noob question....but how do I post pics in the body of my posting?

Just put the url to the pics inside "img" tags, like so:

yourpicture.com

Garry

[georgeorwell]

OK, PTC on the left, white screen on the right.

http://i119.photobucket.com/albums/o131/georgeorwell84/CIMG3380.jpg

[georgeorwell]

OK, let's try a little smaller this time.

http://i119.photobucket.com/albums/o131/georgeorwell84/CIMG3392.jpg

[georgeorwell]

OK, so you're thinking those pics on the white screen look good. Well they do, the AX100 puts out an exceptional black on a white screen. Well, kind of......

http://i119.photobucket.com/albums/o131/georgeorwell84/CIMG3410.jpg

[georgeorwell]

Last one for now. This is a PTC thread, not just SS.

http://i119.photobucket.com/albums/o131/georgeorwell84/CIMG3404.jpg

My opinion. PTC made a big difference on SS. Should be no surprise. SS still has a slight blue push, but overall a good screen.

[georgeorwell]

OK, here are my learnings from the PTC:

1. Open up the can of Behr Poly at the paint counter before buying. I grabbed the best looking can on the shelf, and the inner rim was rusted. If this wasn't a test screen, it would have gone back. I was still able to find a clean spot to pour, but you shouldn't have to do this.
2. As mentioned, don't shake and mix slowly to reduce air bubbles. If you are rolling, this stuff is watery compared to paint, so don't get too agressive with it.
3. OK, I'm ready to be flamed on this one. On my first attempt, I ended up with a work line. I followed the instructions to not overlap or overbrush. It wasn't a very noticeable line, but you could see it with the pj. So I sanded and put up another coat. This time, I very gently (and I mean GENTLY) went back over to smooth over the lines. When it dried, it was absolutely beautiful and looked sprayed on. Whether this has any useen effects, maybe the experts can chime in.
4. GO SLOW. Most of us are used to painting rooms. We try to do a good job, but we also try to get done in time for a Sunday afternoon of beer and football. You really need to concentrate on this to force yourself to break your painting habit and go slow.
5. If you use tape (like I did), remember to remove the tape right after painting. You'll avoid any edging problems by doing this.

Thanks for all the advice above.......

[georgeorwell]

tiddler,
It wasn't you, it was the instructions on the can (no overlap or overbrush). Your paint technique was very helpful, thank you. And my friend would like to thank you as well, this screen looks great.......

http://i119.photobucket.com/albums/o131/georgeorwell84/CIMG3419.jpg

[georgeorwell]

It's an older Casio Exilim, maybe 2 or 3 MP. The shot was taken from about 14', 92" screen. SS base with 2 coats of poly, but the first coat was sanded down pretty good due to my work lines.

[georgeorwell]

pj is an AX100, normal bulb, normal mode....brightness at -5 and color temp at +6 (maxed out).

[bud16415]

Here are my thumbnails of my earliest attempts of both pure flat water based poly over latex paint. The pure poly is the lower left corner the other 3 are different mix rates of poly and paint. I found with my higher lumen projector pure poly as a top coat was too much gain improvement .

With room lights

http://thumb2.webshots.net/t/51/51/1/60/6/2715160060068493142tkQXQI_th.jpg (http://entertainment.webshots.com/photo/2715160060068493142tkQXQI)

With flash

http://thumb2.webshots.net/t/53/153/3/24/49/2823324490068493142fhivwt_th.jpg (http://entertainment.webshots.com/photo/2823324490068493142fhivwt)

Screen images.

http://thumb2.webshots.net/t/58/158/2/43/35/2592243350068493142bnlGyL_th.jpg (http://entertainment.webshots.com/photo/2592243350068493142bnlGyL)

http://thumb2.webshots.net/t/38/38/6/22/20/2472622200068493142ciVwGA_th.jpg (http://entertainment.webshots.com/photo/2472622200068493142ciVwGA)

[demon16v]

This is a cut from my post in "Grays - Simple one can"

Impressions of True Value's Winter Mountain with a BCC top coat;
I let the screen cure for 3 days, did a little wet sanding and put a coat of Behr Crystal Clear on. I was hoping to get some pop from the WM with a topcoat of BCC.

Now, this is where it went wrong for me. I should have first tested it on a sample board. From the results I had with testing BCC on FG laminate I thought it was the way to go.
Wrong.

I applied one coat of poly perfectly. It went on very easy with no roller marks nice and smooth, it was perfect. I let it sit for 6 hours and then hung the screen up. Well, 6 hours was not long enough for it to cure, it was hot spotting. So, I waited a few more days and the hot spotting went away but the image on the screen was a bit unclear (like it was slightly out of focus) and I lost the good black levels. This was not right. I went back to the Avia and DVE discs and recalibrated the PJ. The calibrations were not to far off of what it was set for with straight WM. Strange?? This is just a clear top coat. The real test came on Sunday when it had 6 days to cure and I had everyone over to watch the games. These are the same guys that come over every weekend and they all know a good image when they see one. I never tell them when I’m trying a new screen because I want to know their reaction. They hated it. They were seeing the same things that I saw.

I did try another coat of BCC to see if it would make a difference. It did not. It didn’t make it any worst but it also didn’t make it better.

For me I did not like the BCC top coat and went back to 3 coats of WM until I can do some more testing after the holidays.

Jon

[benven]

Something that has not been discussed much is the effect of applying a coat or two of the Behr Matte Poly over a paint that already has some sheen or is already producing gain through the inclusion of metallic particles.

What I have observed is that a poly top coat over a metallic paint or one with sheen has much less effect. It does not seem to detract from the original screen surface's performance but it may have little effect.

So far I think it works best with a very flat paint. It may also help to tone down a surface with too much sheen.

I concur. Also, flat poly does very little in the way of toning down underlying sheen. At least that has been my observation.

[neekos]

tiddler,
It wasn't you, it was the instructions on the can (no overlap or overbrush). Your paint technique was very helpful, thank you. And my friend would like to thank you as well, this screen looks great.......

http://i119.photobucket.com/albums/o131/georgeorwell84/CIMG3419.jpg


wow!

I don't see the smoothscreen blur that others have complained about with the Panny. There might be a tad softening, but this shot is impressive.

[benven]

Thanks tiddler. First time since Sept. I'm not at the rink on the weekend!!

That's good that the Matte Poly tamed the hotspotting on the laminates. I haven't seen it on glossy painted samples.

No reason why poly would "stick" to a laminate, even one with a bit of texture. Polys are "tough" coatings and are not very flexible. It should flake off as demon noted. However, if you don't move them, it should be OK. But as demon saw, as soon as you start moving your work of art, the poly will crack. Which sucks. And look at how easily, well it seemed like that according to what demon posted, it was to remove the poly on the laminate.

What I found out is that if you use a polymer emulsion, like a Tri Art Matte Polymer emulsion, you get flexibility, adherence and an even flatter gloss than Behr Matte Poly. Problem is that it does not flow out as nice as the Matte Poly. Now, if you mix the 2 components.......you have the best of both worlds. Just a little tip for the new year!!

Season greetings to all!

[benven]

I should have explained myself better. I did use the Behr Matte Poly on the vinyl I sent you. But I primed the vinyl before I used the topcoat. If I didn't prime it, the poly beads up much like water on a waxed car. A laminate is no different than the waxed car analogy. If you were to prime a laminate, I don't think the poly would flake. But that defeats the purpose of using a laminate material.

In your case, you painted your screen first, then topcoated with poly. Thus, I would expect it not to flake off because the paint has some bite to it. Polys are still brittle, but if the substrate has a good tooth, I wouldn't expect any problems. If someone is looking for more adhesion and "matteness", a matte polymer emulsion and matte poly would be the trick.

[wbassett]

My concern after reading this is are the people that followed this and put it on FG going to have a problem? demon rolled his sheet of laminate which is what I suspect caused the cracking. Once it started, it sounds like it basically flaked off. Once mounted and flat and the poly applied I don't see the screen flexing so it shouldn't be an issue.

If the poly isn't a good solution then something else needs to be found, what about a floor sealant/flat poly? That was recommended already by someone.

[1cbr_guy]

After reading this thread, and others addressing top coats, I do have a question. I plan (at this point) to use Sherwin Williams Grey Screen 7071. Then overlaying the Behr matte poly. Does overlaying a poly actually change the gain level, or is it negligible? I think I read somewhere, that it will be less than 1 gain....around .92 AFTER the poly is applied. I guess what I am wondering is what is in the poly that makes it more "reflective?" Is it the sheen (the Behr matte vs. the flat base) that does it? Is there a pearlescene to the poly?

Todd

[prof55]

Welcome back Ben! We've been busy around here...

Garry :D

[demon16v]

Hey Tiddler,

As I said, “I was NOT thinking” when I rolled up the laminate. This is something I should have known. BUT, I was testing some paint mixes and needed to move it out of the way. It also could be because the sheet was moved (rolled up) from a 68 degree room to one that was 55-60. The poly on the laminate was fully cured at the time. If the poly was still new, say 2 days old, it might roll up fine but it would then cure in a rolled up state and would crack when unrolled.

Poly seems like a good way to go. It really helped the FG laminate! I think it will work great on a firm surface such as laminate that has some texture to grip the poly or a pre painted sheet of MDF. I do not think I would use it on a roll up screen as it might crack and flake off.

Just do not do what I did and roll it up and it will be fine.

Wbassett is right, I also think/know it was the rolling up of the laminate that caused it to flake off. I wasn’t thinking at the time.


Jon

[georgeorwell]

wow!

I don't see the smoothscreen blur that others have complained about with the Panny. There might be a tad softening, but this shot is impressive.

Any blur you probably see is me with the camera....you should have seen the prior 5 minutes of video before I captured this shot.

[mech]

I have seen and noted tiddler's concern regarding the poly adhering to a laminate. I thought I'd add my 2 cents. The only prep work done to my FG before applying the poly was a quick wipe with a wet cloth. There were a few pencil marks that had to be cleaned off. Since I applied the 2 coats of poly (screwed up first time) I have probably moved my screen about a half dozen or more times. I had issues with my backlighting and I needed to keep taking it down and putting it back up.

Since then I've seen demon16v's post and the concern regarding the application and adherence of the poly. Went over the screen last night with a "fine toothed comb" and I noticed no abnormalities in the poly layer.

I would concur with demon16v and wbasset's thoughts that the flaking had to do with the fact that demon16v rolled up a poly'd screen. I think it just shows that, depending upon which way demon16v rolled up the FG, the poly is not very tensile or malleable.

mech

[1Time]

I don't see the smoothscreen blur that others have complained about with the Panny. There might be a tad softening, but this shot is impressive.

That is a very nice screenshot. The picture I get with my new AE900U is sharp and not out of focus or blurred at all, yet "smooth". One major plus for me with this Pany is I literally can sit as close to the screen as I want and not see any SDE, just a nice huge, beautiful picture. What I've found makes the most difference between a sharper, more detailed image is whether I use my upscaling Sony DVD player or my HTPC. A better player like the OPPO OPDV971H would provide a sharper picture than my Sony.

That said, my screenshots have always look sharper and generally better than what I see in person. I recall some of the screenshots posted from a couple years ago that were rendered by much lessor projectors, look as good or better than the one last posted. FACT: screenshots easily can be used to represent an image better than it actually looks in person.

[nate358]

So I'm about to roll this stuff on some FG. Should I not use a foam trim roller like what
MississippiMan says to use in the Advanced Roller Painting Instructions:

IMO, since both rollers are 6" ers, I'd omit the use of the 3/16" "Fuzzy" in favor of using only the "Hard Foam Trim" roller. With the "Trim" roller, I have found that if the paint is thin, it can be loaded in the 'well' , rolled out on the 'slope' to reduce the paint load, then applied onto the wall for the first "Hit". Then you go back and "wet it" again on the 'slope' to further extend and "feather" the leading edge.

The rounded edges of the trim roller help very much to prevent Roller marks, unlike the abrupt edges on the "Fuzzy". You might have to re-coat the surface 1-2 times extra because you cannot dump as much paint on initially with a "Trim" as you can a "Fuzzy", but even so, it seems to be enough for me to effect a solid line of paint for up to a 72" tall surface.

The "Two Roller" method you've described is certainly 'do-able;-, but IMO interjects a complexity or procedure than many will find taxing. IMO it's better to get them proficient with one correct method than to interspace two variables.

I went out and bought the 6" foam trim roller and 9" synthetic 3/16 nap roller from HD. Should I use both as to the Advanced Roller Painting Instructions? Or, follow the Basic Roller Painting Instructions and use either roller with my first choice going to the 6" foam roller? I ask about the foam roller because it says right on the Behrs site not to use.... something about air in th roller....
Thanks.

[1Time]

nate358,

The only advise I can give you is to have your laminate situated so it's perfectly flat and so you do not have to move it after you apply the PTC; see post #43 above. Otherwise, I suggest you get in contact with one of these paint pros before proceeding.

[nate358]

thanks guys for the quick response! I just found out I'm not ready to paint :(
As I was setting up to paint the FG. I looked at it and it has a huge bubble in it. I just 3M sprayed it to some Lauan and it didn't turn out so good. It could even be moisture damage to the laminate which is probably unfixable :(
I'm going to start a new thread with all my screw-ups.

[zductive]

There isn't any mention of spraying the poly. Is it not recommended?
I had planned on spraying a 1/4" sintra panel that was painted N7 gray with a poly/pearl topcoat. Will it have airbubles? Should I apply a layer that looks wet or should it just be a very thin layer?

Comments- wagner hvlp is the sprayer that I would use

[bud16415]

There isn't any mention of spraying the poly. Is it not recommended?
I had planned on spraying a 1/4" sintra panel that was painted N7 gray with a poly/pearl topcoat. Will it have airbubles? Should I apply a layer that looks wet or should it just be a very thin layer?

Comments- wagner hvlp is the sprayer that I would use

I’m no expert on spraying poly but in general just about anything can be sprayed with good results. When spraying very light dusting coats of any paint the paints don’t have time to (wet out) and flow smooth and the result will be a texture to the surface finish. The idea of most painting is to allow the texture the paint itself provides so with spraying its always a compromise between getting enough on and not having the paint run. With spraying most times the paint requires more thinning that will allow lighter coats and still adequate wetting.

Some of the spray on screen surfaces like S-I-L-V-E-R actual are based around dusting the paints on and the texture is a desired effect.

But in your case I would think you want the poly to flow out. Always experiment first on a sample is my advice, an extra quart of poly is worth buying if that’s what it takes to perfect your abilities before going at the screen.
:)

[Harpmaker]

I haven't sprayed poly by itself yet, but my guess would be to spray as wet as you can without runs. Spraying with the panel horizontal would also help the poly to flow and not sag. If possible, spray test panels before doing the big one.

[mech]

There isn't any mention of spraying the poly. Is it not recommended?
I had planned on spraying a 1/4" sintra panel that was painted N7 gray with a poly/pearl topcoat. Will it have airbubles? Should I apply a layer that looks wet or should it just be a very thin layer?

Comments- wagner hvlp is the sprayer that I would use
Poly should spray fine. Poly, pearl/poly, and pearlizing/poly all introduce a significant color shift. If you want a lighter brighter screen go with a N9. These topcoats eliminate the purpose behind a neutral screen.

mech

[tiddler]

There is no disputing the fact that polyurethane is not actually crystal clear as the name Behr PREMIUM PLUS WITH STYLE® Crystal Clear Water Based Polyurethane No. #780 (http://www.behr.com/behrx/act/view/products_detail?prodGroupId=21&catName=Faux%2FDecorative+Finishes&catId=18) would suggest. Based on testing performed at the Behr Color Laboratory, two rolled coats of the polyurethane typically reduced the Blue by one or two points. If you are striving for a true neutral gray screen then this can be compensated for by selecting a gray tint that has the red lower than the green and blue. A good example would be Sherwin Williams "Gray Screen". It has an RGB of 199 203 203. The polyurethane would change this to 199 203 202, 199 202 201, or worst case 200 201 200. So in fact it might actually take a very near neutral gray paint and make it even more neutral.

One other consideration regarding a polyurethane top coat is that it does seem to have a softening effect on the image. What I have observed is the light diffusing effect of the polyurethane tends to blur the black lines between the pixels. For some this may mean the image is not as sharp while others may see it as a way to reduce screen door effect and create a more film like image. Either way you should be aware that this does occur. The introduction of some pearl to the polyurethane seems to eliminate this softening.

I would not recommend using a simple polyurethane clear coat on a screen if you will be getting a 1080p projector.

The effect the pearl additives have on color is not quite so well known at this time. Some have reported a blue push with pearl clear coats and some have measured a decided red push. Due to some confusion I am not entirely sure what has been tested though.

Originally I presented some pearl clear coats that were made using Folkart Metallic White Pearl. I found that one or two 2oz. bottles of this white pigment and pearl flakes added to Behr Matte Polyurethane produced a further gain boost without any untoward reduction in viewing cone. At that time the designations 1xPearl and 2xPearl were coined to denote one or two bottles of the Folkart Metallic White Pearl were added to a quart of Behr polyurethane. This naming convention has never changed. I have always suggested two rolled coats and all my testing was done with two rolled coats.

I happened upon a pearlizing medium at Michaels one day and realized that there was an even cleaner source of pearl flakes readily available. I had been resisting the temptation to introduce automotive pearl powders and what not since I was striving for the best I could do with materials the average North American could pickup on the way home from work. I tried the Liquitex, Winsor & Newton, Delta, Decoart, and Folkart iridescent/pearlizing mediums mixed into Behr matte polyurethane. While the Liquitex and Folkart products seem to be very similar the Folkart came in a more suitable sized bottle and was quite a bit cheaper. The Folkart Pearlizing Medium also did not seem to introduce as much unwanted sheen as the Liquitex product. I found the Delta product had very little pearl in it, while the Decoart product had a noticeable red push to it. The W&N medium had much larger and very silver looking flakes that introduced a noticeable sparkling. So I settle on the Folkart Pearlizing Medium as the best performing as well as the most cost effective choice.

The pearlizing medium was a much better source of pearl flakes because it did not introduce the unwanted warm white pigment that the Folkart Metallic White Pearl did. It was my intension to only present the Folkart Pearlizing Medium until people in the USA started reporting difficulties finding the product. Therefore in the end I presented all three methods of implementing a pearl clear coat. The original 1xPearl, 2xPearl clear coats and the purer Pearlizing Clear Coat.

Hopefully that recap of the history of my pearl clear coats investigations will clarify that 1xPearl has nothing to do with the number of coats or the recommended Pearlizing Clear Coat.

I would speculate that the 1xPearl and 2xPearl clear coats will have more effect on color balance due to the warm white pigment they introduce. It was my hope that the pearlizing clear coat would simply introduce a gain boost and light diffusing effect in the polyurethane. Optical Texture was the term that was coined at the time. I have no idea how much any of these pearl clear coats effect the color balance. I do know from extensive side-by-side viewing comparisons that any shift was not immediately apparent. I do however expect that there is some effect and that it can be measured. I also know that it can easily be compensated for by adjusting the base gray.

One very significant difference I noticed between the pearl clear coat approach and the metallic mix approach is that while you can see the pearl flakes in the clear coat when inspected very closely, you do not get the same shimmering effect in the image that I noticed with RS-MaxxMudd and my derivative of it using only Folkart Metallic White Pearl.

I have the means to perform a proper and rigorous set of tests of these pearl clear coats to determine how much relative shift there is in the RGB values. I also have more than enough sample cards with exactly the same gray base applied to them. The absolute RGB of this gray base is not relevant to determining the relative change in RGB due to the three different pearl clear coats and the number of coats applied. As time permits I will make up the following samples and measure the relative differences in RGB readings.

BG (Behr UPW 1050, Qt 6LB + 3YO)
BG + 1 Rolled Coat Behr Polyurethane #780
BG + 2 Rolled Coat Behr Polyurethane #780
BG + 3 Rolled Coat Behr Polyurethane #780
BG + 1 Rolled Coat of 1xPearl Clear Coat
BG + 2 Rolled Coat of 1xPearl Clear Coat
BG + 3 Rolled Coat of 1xPearl Clear Coat
BG + 1 Rolled Coat of 2xPearl Clear Coat
BG + 2 Rolled Coat of 2xPearl Clear Coat
BG + 3 Rolled Coat of 2xPearl Clear Coat

It should then be possible to pick specific brand name paint tints that will have an equal but opposite color profile. The two opposite color shifts will cancel out just as they do with pigments in the neutral gray paints.

It should be apparent that a gray base with a clear coat is a two part application where the two layers should be tailored to work together. The point is that while I have not observed any seriously detrimental color shifting when a pearl clear coat was applied to an existing gray base, it is not the ideal and will no doubt produce a measurable change even if it is not terribly noticeable to the eye. The point being that you should be aware that if you apply a poly or pearl clear coat over a true neutral gray that the RGB will be shifted and possibly more than the acceptable 3 or 4 points.

Let me restate again that my goal is now and always has been to develop the best DIY Screen Paint that I could using readily available products from Home Depot, Michaels, Wal-Mart, and your local fabric store (or similar retailers). I am not suggesting these are the "BEST" solutions. There are other very talented people working on paint solutions employing aluminum powders etc and they have spectrometers and university degrees and know a lot more about color theory than I do. If the very best possible DIY Screen paint is your desire then seek out those individuals and keep watching because they will be presenting some very interesting solutions in the future.

On the other hand, if you just ordered your first projector and it is arriving next week you probably want to throw something together in the way of an interim beginner's projection screen. Then you are the intended audience for my simple DIY painted screen solutions that only employ wall and craft paints.

I have had a chance to do a direct comparison of a Pearlizing Clear Coat sample panel to my buddies Da-Lite High Contrast Matte White retractable screen. The Da-Lite HCMW is a gray base with a pearl clear coat. It also employs a combination of sheen and surface texture. it was difficult to tell them apart right down to being able to see the pearl flakes on close inspection. I'm sure there would be differences if measured with a spectrometer and proper gain curves were plotted. That should qualify what I consider to be an adequate DIY Screen Paint solution.


Pros:

I should mention there are some positives to applying a polyurethane top coat or pearl clear coat. The first advantage is that the surface will be more durable and washable. The other advantage is a gain boost without any serious issues with hot spotting or viewing cone reduction.

A poly or pearl clear coat is not at all necessary. I have had very good results with using matte finish paints alone. I only suggest these top coatings if you want to add a little more gain using stuff you can pickup locally. If you do not want to be bothered with top coating then stick to a good quality matte paint such as Behr's Flat Enamel or better yet the new Behr ULTRA Exterior Flat paint.

[tiddler]

I checked the leftovers from my past Clear Coat Experiments and found that I have most of a quart of the Pearlizing Clear Coat left. I also have several 2oz. bottles of the Folkart Metallic White Pearl. There are more than enough 7"x11" sample cards with a base gray paint already applied. This gray paint was rolled on to all the cards at the same time using the same paint and the same roller. They are as close to identical as I can get them.

I will need to get a quart of Behr Polyurethane. If I mix 1/2 quart of polyurethane with one 2oz. bottle of Folkart Metallic white pearl that will give me the 2xPearl Clear Coat. After I make up the three 2xPearl sample cards, I will mix equal parts of the remaining 2xPearl with polyurethane. That will provide the 1xPearl Clear Coat. Hopefully there will be enough polyurethane left over to make up the three poly only sample cards.

I will allow these samples to cure for a minimum of 3 days and then do relative RGB measurements to determine the color shifting effect of the various clear coats and number of coats.

It is my contention that if we know how the clear coats shift the RGB color profile then we can look for an equal and oposite in the RGB color profile of the base gray. I already know that the pearl clear coats effectively lighten the shade of gray that the final screen will be. To maintain the desired shade of gray we will know how much darker the base gray will need to be. I will probably follow my own suggestions at the end to prepare for painting my neighbor's screen this winter.


By the time I get this done with this final set of investigations into Pearl Clear Coats, I hope to be getting to the "Controlling Gain & Viewing Cone" part of the Beginner's Guide To Simple DIY Painted Screens (http://www.avsforum.com/avs-vb/showthread.php?t=929997).

[tiddler]

Just some preliminary results.

This is for the Pearlizing Clear Coat which is one 2oz. bottle of Folkart Pearlizinug Medium added to one quart of Behr Matte Polyurethane #780.

One coat pulls the RGB numbers down pretty evenly by 1 or 2 points. Two coats was also pretty even with a reduction of around 3 points. Three coats caused a drop of 3 to 4 points with the red being consistently less so the delta RGB was -2 -3 -3 or -3 -4 -4

So far I would say the color shifting seems pretty minimal. These delta measurements are also consistent with what I observe looking at the samples. At least as far as color shifting goes.

I would expect the 1xPearl and 2xPearl will not be so balanced. The warm white pigment in the Metallic White Pearl is bound to have some color shifting effect. That is why I went on a search for a cleaner source of pearl flakes. The color shifting will be compounded by the combination of the blue green filtering effect of the polyurethane and the warm white pigment.

I should also point out that the pearlizing mediums are not all the same. The Decoart Pearlizing Medium had a decided red push to it. So when I suggest "FOLKART" Pearlizing Medium I mean only Folkart. There is also a big difference between the Folkart Pearlizing Medium and the Folkart Metallic White Pearl. Many people seem to think the two are interchangeable and they are not. The Folkart Pearlizing Medium is by far the better choice and will introduce the least amount of color shifting.

[mech]

Todd,

If you'd like for me to take readings of this with my spectro, I will. I'd need one of the original base coat and then whatever topcoats. If you send me large enough sizes I can get other measurements as well.

mech

[tiddler]

Todd,

If you'd like for me to take readings of this with my spectro, I will. I'd need one of the original base coat and then whatever topcoats. If you send me large enough sizes I can get other measurements as well.

mechThanks for the offer mech. :)

I've been pretty slow at making up the sample cards. When they are prepared I can send either 7.5"x11" or 3.25"x7.5" samples.

[mech]

7.5 X 11 would be best.

mech