The Official Polyurethane Top Coat (PTC) Thread - AVS Forum
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post #1 of 45 Old 12-15-2006, 08:23 AM - Thread Starter
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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.

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.

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

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
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post #2 of 45 Old 12-15-2006, 08:52 AM
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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.
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post #3 of 45 Old 12-15-2006, 09:09 AM - Thread Starter
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Quote:
Originally Posted by georgeorwell View Post

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.
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post #4 of 45 Old 12-15-2006, 09:36 AM
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Quote:


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
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post #5 of 45 Old 12-15-2006, 10:36 AM
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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.
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post #6 of 45 Old 12-15-2006, 11:24 AM - Thread Starter
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Quote:
Originally Posted by georgeorwell View Post

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.
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post #7 of 45 Old 12-15-2006, 11:55 AM
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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 .

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post #8 of 45 Old 12-15-2006, 12:09 PM
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Great info...thanks! I'm off to Home Depot to get a few more materials.
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post #9 of 45 Old 12-15-2006, 01:49 PM
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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/...c-Flow-Aid.htm
http://www.misterart.com/store/view/...d-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
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post #10 of 45 Old 12-16-2006, 10:23 AM
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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?
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post #11 of 45 Old 12-16-2006, 10:31 AM
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Quote:
Originally Posted by georgeorwell View Post

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:

[img]yourpicture.com[/img]

Garry
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post #12 of 45 Old 12-16-2006, 10:46 AM
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OK, PTC on the left, white screen on the right.

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post #13 of 45 Old 12-16-2006, 10:52 AM
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OK, let's try a little smaller this time.

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post #14 of 45 Old 12-16-2006, 11:00 AM
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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......

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post #15 of 45 Old 12-16-2006, 11:07 AM
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Last one for now. This is a PTC thread, not just SS.



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.
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post #16 of 45 Old 12-17-2006, 08:04 AM
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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.......
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post #17 of 45 Old 12-18-2006, 05:21 AM
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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.......

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post #18 of 45 Old 12-18-2006, 06:09 AM
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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.
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post #19 of 45 Old 12-18-2006, 06:12 AM
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pj is an AX100, normal bulb, normal mode....brightness at -5 and color temp at +6 (maxed out).
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post #20 of 45 Old 12-18-2006, 11:33 AM
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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



With flash



Screen images.





Bud

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post #21 of 45 Old 12-20-2006, 10:04 PM
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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
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post #22 of 45 Old 12-23-2006, 06:17 AM
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Quote:
Originally Posted by tiddler View Post

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.

Meow.
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post #23 of 45 Old 12-23-2006, 06:38 AM
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Quote:
Originally Posted by georgeorwell View Post

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.......



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.
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post #24 of 45 Old 12-23-2006, 06:49 AM
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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!

Meow.
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post #25 of 45 Old 12-23-2006, 12:57 PM
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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.

Meow.
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post #26 of 45 Old 12-23-2006, 01:49 PM
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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.

"Make everything as simple as possible, but no simpler." - Albert Einstein
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post #27 of 45 Old 12-23-2006, 02:59 PM
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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
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post #28 of 45 Old 12-23-2006, 06:41 PM
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Welcome back Ben! We've been busy around here...

Garry
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post #29 of 45 Old 12-23-2006, 11:03 PM
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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
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post #30 of 45 Old 12-24-2006, 05:46 AM
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Quote:
Originally Posted by neekos View Post

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.
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