[Prognathous]

I recently purchased a BenQ W1080ST+ projector and I'm using my living room wall for projection. I don't plan to buy a screen because I don't want to invest so much to get rid of waves, and using a wall seems like an easy solution to this issue. Now, despite my wall texture being quite rough and the paint being some random matte stuff that the previous tenant painted I enjoy watching movies very much. I guess it means that my standards are not very high, and that I might be able to keep things simple when repainting. With this in mind I'd hope you can help me understand the following:

1. Can I get a reasonable result without the joint compound by just applying a layer of primer, sanding it and then painting the wall?
2. Is one layer of primer and one layer of paint sufficient or is it essential to do multiple layers?
3. Do I need to finish with sanding, or just the paint?

Basically, is there a way to invest 20% of the efforts of a multi-layer multi-material job and get 80% of the quality?

Thanks in advance!

 

[Ftoast]

If you're trying to get a smoother screen/surface while skipping the joint-compound, you can instead just fully sand down the wall texture where you need it smooth, but it might take more sanding compared to the compound depending what was used to create the texture in the first place.
It shouldn't hurt to try sanding an inconspicuous area to test if it's something you can stand doing over a large surface.

Either way, once you've gotten the surface smooth you should be in good shape.
Multiple layers of primer shouldn't be required..just getting it coated so the paint can hold without getting sucked into the raw drywall.
I don't think additional sanding will be needed if you're sticking with flat/matte-white. The smoother starting point will make the largest difference.

If you decide to try something that fights ambient light later on, the smoothed wall and white primer+paint will be a great starting-point too.

 

[Prognathous]

If you're trying to get a smoother screen/surface while skipping the joint-compound, you can instead just fully sand down the wall texture where you need it smooth, but it might take more sanding compared to the compound depending what was used to create the texture in the first place.
It shouldn't hurt to try sanding an inconspicuous area to test if it's something you can stand doing over a large surface.

Either way, once you've gotten the surface smooth you should be in good shape.
Multiple layers of primer shouldn't be required..just getting it coated so the paint can hold without getting sucked into the raw drywall.
I don't think additional sanding will be needed if you're sticking with flat/matte-white. The smoother starting point will make the largest difference.

If you decide to try something that fights ambient light later on, the smoothed wall and white primer+paint will be a great starting-point too.

Thank you so much. It makes a lot of sense. I'll check out the sand->primer->paint order on a hidden spot on an inconspicuous space and will update about the result.

I intend to use the projector only when the room is completely dark, so not worried about ambient light.

 

[MississippiMan]

I recently purchased a BenQ W1080ST+ projector and I'm using my living room wall for projection. I don't plan to buy a screen because I don't want to invest so much to get rid of waves, and using a wall seems like an easy solution to this issue.

Well I see posts where people state how they don't want to go to too much trouble, but not nearly as many who go to such lengths to describe how poor their surface is to start out with.

If the Drywall itself is hung so that it has noticeable waves from uneven framing, there is nothing that sanding or even a skim coat of compound will take care of.

Personally...and this might sound a bit more rough than I normally express...I think your just trying to be a bit too lazy here. The available fixes are NOT expensive.....they simply require you to do SOMETHING to make things not just noticeably better, but exponentially better.

So read on and then let me either "have it", or take some good advice and wind up with a big picture you can be proud of.

Now, despite my wall texture being quite rough and the paint being some random matte stuff that the previous tenant painted I enjoy watching movies very much. I guess it means that my standards are not very high, and that I might be able to keep things simple when repainting. With this in mind I'd hope you can help me understand the following:

1. Can I get a reasonable result without the joint compound by just applying a layer of primer, sanding it and then painting the wall?

NO. All applying primer itself will only serve to change the wall color to white and prep the surface for a different paint. It will do nothing to hide the existing texture. Sanding after priming will mean you have to sand off the Primer to reach the root of your "Texture" problem. Of course that would still do nothing to solve your "Waves".

The most you could expect doing the least amount of work is to rid yourself of "some" of the noticeable bumpy texture by using a completely Flat Primer and Paint.

The "BEST" possible results would be from your taping off the desired screen area, taking a Medium Grit "Large" Sanding sponge, and sanding down the painted texture to a smooth as possible state. (elbow grease required). DO NOT sand to the point you see Drywall paper.
Then apply your Primer & Paint.

2. Is one layer of primer and one layer of paint sufficient or is it essential to do multiple layers?

If your Rolling (...and it is to be assumed you are...) you should / would have to apply at least 2 coats of Primer, and 2 coats of Paint

3. Do I need to finish with sanding, or just the paint?

That depends upon how well you can Roll apply the finish paint. In the least, wait a Day, shoot several different images onto the surface and inspect for Roller Marks. If any are present, sand the surface again and re-roll.

Basically, is there a way to invest 20% of the efforts of a multi-layer multi-material job and get 80% of the quality?

If only that were true, I'd have to answer far fewer questions.

Thanks in advance!

Frankly speaking...and lower expectations considered....with all the issues your facing you should consider instead using a solid substrate. That is unless your Image Quality expectations are lower than your screen size expectations.

You knock one out of the park if your screen size falls to 98" diagonal or less, because there are smooth "Wave & Texture" free materials for under $20.00 you could simply roll on some Flat paint onto and you'd get past even that 80% improvement level.

Larger? There is Sintra or even BOC that would come into play..

Your biggest issue is that you obviously do not have any reference as to how extreme the difference would be if you did have a more acceptable surface. Because if you did....we would not be having this discussion about making do with a substandard surface.

OK...I have both feet firmly planted. Either give me your best shot...or take your best shot at going for something to be proud of.
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.
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Post Note:
I see your answer to ftoast's reply, which somewhat mirrors my own suggestion to sand first then Prime & Paint. I really don't think any "test" is needed....just go ahead and do it.

 

[Prognathous]

MississippiMan, thank you for the detailed reply. A lot of room for thought there. Let me just clarify one thing that I wrote and that I seem to have phrased poorly:

I don't plan to buy a screen because I don't want to invest so much to get rid of waves, and using a wall seems like an easy solution to this issue.

I didn't mean to say that my wall has waves. It does not (at least none that I can see or be annoyed by). I meant to say that I read many reports about regular screens (non-tab-tensioned ones) having an issue of waves. Since I don't plan to invest in a tab-tensioned screen, the decision between a painted wall and a regular screen makes me favor the former, because I know the result will be free from waves. Does this make sense?

Another thing that I failed to mention, and I see now that it's very much relevant, is that the wall is not made-of or covered in drywall but rather plaster.

Personally...and this might sound a bit more rough than I normally express...I think your just trying to be a bit too lazy here. The available fixes are NOT expensive.....they simply require you to do SOMETHING to make things not just noticeably better, but exponentially better.

I openly admit to being lazy here. The reason is that I have a (possibly unfounded) feeling that I can get a result I'll be content with, without going through a long and expensive process. I don't even know if I'll rent this apartment next year so going the extra mile or dollar is problematic.

So read on and then let me either "have it", or take some good advice and wind up with a big picture you can be proud of.

I'm definitely in. Thanks again for spending the time and going into so much detail.

NO. All applying primer itself will only serve to change the wall color to white and prep the surface for a different paint. It will do nothing to hide the existing texture. Sanding after priming will mean you have to sand off the Primer to reach the root of your "Texture" problem.

Got it. Sand first, then primer. Does it work the same with plaster walls too, or are there other considerations?

The "BEST" possible results would be from your taping off the desired screen area, taking a Medium Grit "Large" Sanding sponge, and sanding down the painted texture to a smooth as possible state. (elbow grease required). DO NOT sand to the point you see Drywall paper.

I borrowed a random orbit sander from a friend. Any reason to use a sanding sponge instead? I assume a dedicated power tool would be less demanding, elbow-grease-wise.

And as I mentioned above, there is no drywall so getting to the drywall paper is not an issue.

If your Rolling (...and it is to be assumed you are...) you should / would have to apply at least 2 coats of Primer, and 2 coats of Paint
That depends upon how well you can Roll apply the finish paint. In the least, wait a Day, shoot several different images onto the surface and inspect for Roller Marks. If any are present, sand the surface again and re-roll.

Yes, of course I'm rolling. I specifically bought a short nap roller for this project.

Is the purpose of sanding imperfections to improve a layer, or to wipe it off and start again? In other words, if I sand imperfections on the first layer, does that mean I'm back to layer 0 or can I consider as layer 1 (out of the minimum recommended 2)?

Frankly speaking...and lower expectations considered....with all the issues your facing you should consider instead using a solid substrate. That is unless your Image Quality expectations are lower than your screen size expectations.
You knock one out of the park if your screen size falls to 98" diagonal or less, because there are smooth "Wave & Texture" free materials for under $20.00 you could simply roll on some Flat paint onto and you'd get past even that 80% improvement level.
Larger? There is Sintra or even BOC that would come into play..

98" should be fine (my wall is 7 feet / 2.10m wide). If I understand correctly we're talking about solid plates here? I wonder how does one fit them through the door / elevator?

Your biggest issue is that you obviously do not have any reference as to how extreme the difference would be if you did have a more acceptable surface. Because if you did....we would not be having this discussion about making do with a substandard surface.

Ignorance is bliss…

But seriously, I'm pretty sure that I'll end up with a solution I'll be happy with, even if it requires more than the minimal effort I was hoping for. I'm ready to do more, within reason (rented apartment etc…)

 

[Ftoast]

Depending on the style of plaster, you may never be able to get the wall itself as smooth as the compound (if you were to lay it over top as you're trying to avoid presently)..it'll still be worlds smoother than it is right now, so you'll still see a nice improvement.

A 98" solid panel will only need to be about 7ft tall and 4ft wide and should fit through most doorways easily enough, mostly because it should be pretty lightweight and easy to maneuver. That would save you from all forms of sanding and wall-prep work.

The later sanding would just be a light overall sand to smooth out roller-marks and any stray imperfections before the final coat.

If you're sticking with flat/matte-white for now, that'll help hide imperfections too..it's likely the biggest current contributor for how you can enjoy watching on the bumpy wall right now. Flat paint is super forgiving like that.

 

[MississippiMan]

Plaster eh,

Well ftoast is right.

You'll have to be very good with the Orbital, and do a well nigh perfect job, or you'll see varying areas of texture, swirl marks, etc.

Myself, the last screen I did on a Plaster Wall, I first used a 4" wide scraper to knock off the high points, then I used a coarse grain Sponge, and sanded the remaining top points as smooth as possible.

THEN...I skimmed the wall with lightweight Drywall Compound 2x to fill in the areas between the bumps....sanding the last coat. Then I Primed and Sprayed.

I did all this 20' off the ground on a 12' wide drivable Scissor Lift and the screen area was 180" "wide".

It was in a Brewery call "Green Flash" in San Diego, and I had free access to over 20 different Beer Taps.

...........and I STILL got'ter dun.

Now waddya want to say?


In any case, a 85" x 48" piece of anything somewhat flexible and smooth is a great starting point.

\Just exactly where do you reside? You used a metric figure so I'm thinking somewhere across the Pond, and if so, that will go a ways toward determining what material might be available to you...and your budget.

Somehow I see you stating you live on the 3rd Floor Flat in London or sumpthin'.

 

[Prognathous]

A 98" solid panel will only need to be about 7ft tall and 4ft wide and should fit through most doorways easily enough, mostly because it should be pretty lightweight and easy to maneuver. That would save you from all forms of sanding and wall-prep work.

That's a good point. I found some polystyrene foam boards (e.g. KAPA) which are very inexpensive and I'm sure will be much smoother than my wall. The boards are white, so I wonder if I could use them as-is, without painting at all?

If you're sticking with flat/matte-white for now, that'll help hide imperfections too..it's likely the biggest current contributor for how you can enjoy watching on the bumpy wall right now. Flat paint is super forgiving like that.

There had to be a logical explanation for that

BTW, the paint that I bought has satin finish, but I might end up not using it if the KAPA board can do the trick.

You'll have to be very good with the Orbital, and do a well nigh perfect job, or you'll see varying areas of texture, swirl marks, etc.

Considering I've never used this tool, the chances I'll do a perfect job are practically zero.

Myself, the last screen I did on a Plaster Wall, I first used a 4" wide scraper to knock off the high points, then I used a coarse grain Sponge, and sanded the remaining top points as smooth as possible.

THEN...I skimmed the wall with lightweight Drywall Compound 2x to fill in the areas between the bumps....sanding the last coat. Then I Primed and Sprayed.

I did all this 20' off the ground on a 12' wide drivable Scissor Lift and the screen area was 180" "wide".

It was in a Brewery call "Green Flash" in San Diego, and I had free access to over 20 different Beer Taps.

...........and I STILL got'ter dun.

Now waddya want to say?

Well, I'd say that the beer is the only thing here that sounds appealing. Well, the result too. Man that sounds like a lot of work.

In any case, a 85" x 48" piece of anything somewhat flexible and smooth is a great starting point.

I found boards that are 244cm x 122cm / 96" x 48" and are really inexpensive. The equivalent of 25 USD or so. They come in two thickness options 10mm and 5mm (not sure how to write that in inches - 2/5" and 1/5"?). I assume the thicker board will look less aesthetic, so I'm tending toward the thinner option.

\Just exactly where do you reside? You used a metric figure so I'm thinking somewhere across the Pond, and if so, that will go a ways toward determining what material might be available to you...and your budget.

I live in Israel, across the Pond and then some...

Somehow I see you stating you live on the 3rd Floor Flat in London or sumpthin'.

Haha, wouldn't that be nice?

 

[Ftoast]

The 10mm panel will stay straighter for you. If the 10mm doesn't feel terribly heavy and is still affordable (sounds like it's doing well in both regards) I'd put my vote toward that.

If the foam is smooth, closed-cell or coated, and tough enough to hold together without falling apart, you can certainly try it if it's cheap enough to not bother you if it doesn't work out...otherwise I'd stick to the 10mm panel.

The satin paint will show bumps and painting flaws much more noticeably and can also hotspot with a bright image shown on it (that bright-centered spotlight look). I'm not sure if you'll be allowed to exchange it for flat/matte-white at the store, but I'd try.

If you do end up painting anything (panel or foam), make sure you paint both sides. Painting just one side will gradually warp most panels as the paint cures..alternatively you can brace whatever you're using with a poplar frame, but I'd suggest painting both sides either way. It hurts nothing.

 

[Prognathous]

The 10mm panel will stay straighter for you. If the 10mm doesn't feel terribly heavy and is still affordable (sounds like it's doing well in both regards) I'd put my vote toward that.

I'll get the 10mm panel then. It's not a huge risk in terms of cost.

The satin paint will show bumps and painting flaws much more noticeably and can also hotspot with a bright image shown on it (that bright-centered spotlight look). I'm not sure if you'll be allowed to exchange it for flat/matte-white at the store, but I'd try.

I doubt I still have the receipt.

The reason I bought the satin finish paint was this page. Quote:

While the Valspar's Base 1 with no added pigment was reasonably solid in color balance, the Matte finish that we started with rendered an image that was unacceptably dull compared to the Studiotek 100. Valspar comes in a variety of finishes that increase in sheen, including Matte, Eggshell, Satin, Semi-Gloss, and Glossy. Since the Matte was too dull, we moved on to Eggshell--better, but still a bit dull. Next we tried the Satin. This one looked quite acceptable--not perfect, but a very nice picture. Stepping up to the Semi-Gloss, we suddenly overshot the runway; the Semi-Gloss was way too shiny, creating a host of annoying hotspots and artifacts that made it useless.

Isn't the hoptspot also projector-specific? My projector is a short-throw BenQ W1080ST+. Would the fact that it's relatively at a steeper angle to the screen reduce the likelihood of a hotspot compared to a projector that's further away from the screen and thus relatively closer to the point of view of the viewer? I know that if I aim a torchlight at a shiny surface, the closer the light source is to eye level the higher the chance of seeing a reflection. Not sure if this logic applies to projectors, but if it does, that could be a nice bonus of owning a short-throw projector...

BTW, the stores where I can buy the panel are closed here on Saturday, so I'm thinking about painting the wall anyway. The size of the wall is about 2.7x2.1 meter (or 7x9 feet). Any estimate for how much time it would take to sand it with an orbital, apply primer, let it dry, then paint it using a 23cm / 9" roller (with 4mm nap)?

 

[Ftoast]

The short-throw because of the steeper angle will be MORE likely to hotspot with shiny paint. Also, the paint mentioned in that article changed its formula some time later and made quite a few folks upset for that very reason(new version was too shiny)..a few specific paints can get away with eggshell, but most work best with flat/matte. Also remember that any flaws in the wall or roller-marks from painting will be more noticeable with the shinier paint.

I don't think it'll hurt anything to try it and then just paint over with flat/matte if you don't like it. There's always the small chance you won't notice the hotspotting and will appreciate the added gain, I've heard one or two people come away happy using somewhat glossy paint.
At least if you don't like it, flat/matte is even cheaper than satin, so painting over won't hurt the wallet.

MM or someone else will have to chime in with a time estimate.

I hope future updates include pictures.

 

[Prognathous]

I started sanding the wall today using the orbital sander. My initial impression is that even with #40 grit sandpaper it's a slow process that requires a lot of patience. Also my hands feel really weird after I turn off the sander. And to think that when I'm done with this step I'll have to do it all over again with a #120 grit sandpaper... I'm beginning to think I'll only sand the middle part of the wall, where the projected image is. I hope the difference between the sanded and un-sanded parts won't be too visible otherwise.

Another issue is dust. Given that my sander is supposed to collect dust (and indeed it does), there's way more of it in the room than I expected. It gets everywhere. I'll buy some more plastic covers for the room to try to mitigate this issue. I'll also get gloves to reduce the vibrations from the sander to some degree.

Any thoughts and suggestions welcome.

 

[Ftoast]

Talking about how slow it's going makes me wonder if it'd be possible to use a belt-sander for the initial job of knocking things flat. I love the belt-sander for wood because it's ridiculously fast, but it could probably sand a hole through the wall, lol.
Using that to start and then the orbital and finally hand to finish might work.

If doing just the screen area looks too different, would a frame around the screen be an option?

 

[gonzo90017]

You knock one out of the park if your screen size falls to 98" diagonal or less, because there are smooth "Wave & Texture" free materials for under $20.00 you could simply roll on some Flat paint onto and you'd get past even that 80% improvement level.

Mind sharing with us what all of these materials are?

 

[Ftoast]

Mind sharing with us what all of these materials are?

I've been using 1/4" 4x8 wall panels from homedepot.
These particular ones are made to look like a light woodgrain but are perfectly smooth to the touch. Lightweight despite being MDF and only $8

I'll post a picture of the tag in a minute...once I find it.

 

[Prognathous]

I finished coarse sanding the wall and was about to start doing fine sanding, but first decided to fill a hole. I used joint compound for that, and for the heck of it covered a few areas where the wall was still pretty coarse. Man, I don't know what made me come up with that question in the OP. This stuff is so easy to use, I don't know why I wasted so much time and effort sanding. Am I missing something, or should I simply use joint compound to smooth the wall and do minimal fine sanding for imperfections? That's what seem to make the most sense now.

 

[MississippiMan]

I finished coarse sanding the wall and was about to start doing fine sanding, but first decided to fill a hole. I used joint compound for that, and for the heck of it covered a few areas where the wall was still pretty coarse. Man, I don't know what made me come up with that question in the OP. This stuff is so easy to use, I don't know why I wasted so much time and effort sanding. Am I missing something, or should I simply use joint compound to smooth the wall and do minimal fine sanding for imperfections? That's what seem to make the most sense now.

That's what I would do...and what I do.......

.......and if after sanding and a primer coat or two I discover a few additional spots, I hit them as well with a light coat of Mud, sand, and spot prime a couple coats then continue priming. The wee bit of extra effort pays immense dividends considering how really little time & effort it all takes.

The truth of it is when dealing with adverse wall texture, knocking down the high points then skimming to level out the surface is really the best, easiest, most assured way of creating a virtually perfect surface, and hence...a perfect screen.