Smoothing wall for projector

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  #1  
Old 05-10-12, 10:51 PM
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Smoothing wall for projector

Hi, I would like to implement what described at the following link to "paint" a projector screen on the wall:

Painting the Perfect Screen for $100

My walls have been re-done few years ago by the previous owner and look like this:

Imagebin - A place to slap up your images.

I am not sure how to proceed to smooth the wall. I really want to do a good job. The screen should be in the 120" range, relatively big but I hope I can smooth it in about half day of work.
Which tools should I use? If I had to improvise I would get a flat tool similar in size to a letter page with a handle and apply sandpaper on it starting with coarse and then going down to ultra-fine, and I would do the job with a potent light set in the corner to highlight all the imperfections... or should I get an electric tool?

Thanks for any advice!!!
 
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Old 05-11-12, 05:08 AM
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Latex paint can gum up sandpaper especially the harder/faster you sand. I'd take a drywall knife and gently scrape off any high spots and then apply a coat of joint compound. Sand when dry, touch up the j/c if needed and it should be ready for primer and paint.
 
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Old 05-11-12, 07:38 AM
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Hi! Thanks. How do you know it's latex paint? Can you determine that from the picture I posted?

For drywall knife you mean something like that:

10" Stainless Steel Taping Knife

I have to do some research about the "joint compound" and how to apply it! I hope this does not get more complicated that what I thought.
 
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Old 05-11-12, 09:08 AM
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99.9% of all residential walls today are painted with latex paint. i don't know for sure you have latex paint on walls but assume you do. http://www.doityourself.com/forum/pa...latex-oil.html

The drywall knife should work fine. Joint compound is what the drywall finisher used to mud all your seams and nail/screw heads. It applies best if you thin it slightly. Basically you just want to apply a thin coat of j/c, just enough to make the wall smooth. It sands easy but the dust is very messy.
 
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Old 05-11-12, 10:07 AM
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Thanks I will try! Is it necessary to use denaturaded alcohol or normal isopropyl is fine?
 
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Old 05-11-12, 10:09 AM
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Regular old drugstore isopropyl should be fine.
 
  #7  
Old 05-12-12, 10:28 AM
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OK which product do you think I should buy for the joint compound? I have never used any, how much should I buy for this screen, that will be about 10x6 feet? Which tool to apply it?
 
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Old 05-12-12, 12:15 PM
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I always buy the 5 gallon buckets of mud but they also sell j/c in 1 gallon containers [that's all you'll need] I've never really paid much attention to the brand name although USG is one of the major brands. Most any j/c is fine for your needs.

The 10" knife you provided a link for will work fine. You just want to apply a thin layer as smooth as you can, let it dry, sand and then see if it needs any more mud. You'll need either a pan or hawk to work out of. I like to use a pan but if you don't want to buy one you could take a smooth piece of plywood and make a hawk.
 
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Old 05-12-12, 03:46 PM
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Good! In the meanwhile I have mounted the projector on the ceiling and outlined the exact screen size on the wall. Unfortunately to keep the projected screen central, the upper left corner is intercepted by the ceiling fan - I will have to remove it! We have never used it anyway.
 
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Old 05-14-12, 01:02 AM
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You'll get better results using a steel concrete finishing trowel instead of the drywall trowel. "Been there, done that" too many times. A 4" x 14" works best. Broad, semi-circular strokes, working from top to bottom (heel in, toe out). The concrete trowel lets you float and work the mud in without leaving ridges. And yes, don't forget the hawk.
 
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Old 05-14-12, 01:17 AM
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I've read that it's possible to remove latex paint using alcohol. Do you think I should spray it on the wall to remove the high spots and possibly most of the paint before applying the j/c?
 
  #12  
Old 05-14-12, 04:34 AM
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The high spots are from the texture which is probably made from thinned down joint compound sprayed thru a hopper and then flattened out with a wide knife. There would be no benefit from removing the latex paint although a quick scuff sand is always beneficial.

I think using a concrete trowel versus a drywall knife depends on what you are comfortable using. I'm sure I would get a better job using a drywall knife - but that's what I've always used. Unlike BridgeMan, I have limited experience with concrete work. A trowel would definitely need a hawk as it couldn't be used with a mud pan.
 
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