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The Official Polyurethane Top Coat (PTC) Thread - Page 2

post #31 of 45
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.

post #32 of 45
Thread Starter 
Originally Posted by neekos View Post

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.
post #33 of 45
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....
post #34 of 45
Thread Starter 

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.
post #35 of 45
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.
post #36 of 45
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
post #37 of 45
Originally Posted by zductive View Post

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.
post #38 of 45
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.
post #39 of 45
Originally Posted by zductive View Post

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.

post #40 of 45
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 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.
  1. BG (Behr UPW 1050, Qt 6LB + 3YO)
  2. BG + 1 Rolled Coat Behr Polyurethane #780
  3. BG + 2 Rolled Coat Behr Polyurethane #780
  4. BG + 3 Rolled Coat Behr Polyurethane #780
  5. BG + 1 Rolled Coat of 1xPearl Clear Coat
  6. BG + 2 Rolled Coat of 1xPearl Clear Coat
  7. BG + 3 Rolled Coat of 1xPearl Clear Coat
  8. BG + 1 Rolled Coat of 2xPearl Clear Coat
  9. BG + 2 Rolled Coat of 2xPearl Clear Coat
  10. 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.


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.
post #41 of 45
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.
post #42 of 45
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.
post #43 of 45

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.

post #44 of 45
Originally Posted by mech View Post


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.


Thanks 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.
post #45 of 45
7.5 X 11 would be best.

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