Painting; Sanding walls before adding a new layer of paint

Submitted by simon_chess123 t3_11bru5s in DIY

Hello

I have been scouring Reddit for advice on sanding a wall before painting, generally in my case the wall is smooth, with a few paint streaks and some holes that I have filled and sanded down already.

The consensus seems to me that sanding the wall before applying paint is unnecessary. However if I am looking for a really nice finish, is there any advantage to sanding the rest of the wall? This question I have not found covered much in my search. FYI I am applying several coats of water-based paint over a layer of water-based paint, so I don't think I need to prime first. Any help would be appreciated thanks

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EmpatheticNihilism t1_j9zhz7h wrote

Painter for 15 years. Just paint it.

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Character-Barracuda1 t1_ja0q1fv wrote

Primer first?

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TimeSlipperWHOOPS t1_ja103ob wrote

Primer is cheaper than paint. Some times you need more coats than expected for full coverage. I painted a pink room blue no primer no problem. I painted a brown room yellow with no primer and wish I used it because I needed way more yellow than expected.

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EmpatheticNihilism t1_ja4c5qn wrote

Depends if you’re changing the type of paint oil over latex or drastically changing the color. Otherwise just paint it twice. Sometimes with primer you’ll end up painting 3 times. 1 primer 2 finish color

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Joe30174 t1_j9zljzg wrote

Im not a painter, so if there is one who can correct me if I'm wrong, I'd appreciate it.

I like to do a good scuff sand on semi glossy and glossy walls before painting. Cleaning the walls obviously as well. If not, the paint seems fairly easy to peel off afterward.

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No_Pomegranate2580 t1_j9zjknv wrote

Cleaning it is more important than sanding it in my opinion. Sanding is just a preference, how smooth do you want your wall to be?

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simon_chess123 OP t1_j9zko60 wrote

Aspirationally I would like it to look like the advertisement material online (wouldn't we all. Here; https://www.duluxheritage.co.uk/en/colours/1780077/florentine-red) I know the image has been through digital processing and therefore perhaps unrealistic. If I can achieve something similar without sanding and just cleaning then I won't bother. Also I do have an orbital sander and 120 grit discs so I don't think it'll be too long to do but lots of dust and cleaning afterward

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nhorvath t1_ja2xctt wrote

An orbital sander is the wrong tool. If you're going to sand you use a pole sander in the 220 to 400 grit range. Just one quick pass to knock down high spots and dust nibs.

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No_Pomegranate2580 t1_ja478l1 wrote

That is exactly correct. They have both electric and hand powered ones, I prefer the latter.

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simon_chess123 OP t1_j9zlih7 wrote

hmm maybe I didn't answer the question. I prefer the smoothness of the patches that were sanded for holes but I am more concerned about having a really grainy or lumpy finish due to really small imperfections

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No_Pomegranate2580 t1_ja46ucu wrote

Then sand it. They make a special sander for drywall, a pole with a metal attachment. That makes it easier in my opinion.

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Bammer7 t1_ja0e9vq wrote

You would be amazed at how effective just wiping down the wall with some light cleaner and warm water is. If you really feel you need to sand it, get some fine grit drywall sandpaper or screens and a pole sander. Then just lightly go over it to smooth it out. Make sure you get any dust off the wall before you paint it.

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danauns t1_ja1gu1p wrote

Though sanding isn't explicitly necessary, it is absolutely a step that can be added to GREATLY upgrade your results.

The end result is absolutely night and day different. Steps include:

  • Remove all wall plates, lights, fixtures so that the entire wall is exposed. Tape where necessary, switches for example.
  • scrub the entire wall with a TSP solution to remove all surface grime.
  • pole sand the entire wall.
  • hand sand around every outlet and switch, these areas get extra shabby over the years.

Then paint. You will with out question see a difference.

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TootsNYC t1_ja345wd wrote

You forgot that you should remove the dust before painting.

I find a sacrificial microfiber cloth is really good. And then run a damp cloth over it afterward.

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mynaneisjustguy t1_j9zv8uq wrote

Well; if you want to make a mirror finish you must sand. But I reserve that effort for boats. For walls; sand if it feels rough or “hairy” otherwise just paint nicely and maybe tip off.

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nishnawbe61 t1_j9zyhn1 wrote

If you filled any holes you have to put primer on those spots or you will see them when you're done painting. Sanding will not make the paint finish look better, just paint it.

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splifingate t1_ja0nhf1 wrote

Personally, I have a high tolerance for errousness/imperfection, and I just skim-off the pronounced bits with a putty blade, rough sand, then prime&paint.

I tend to fuel my OCD a bit more when it comes to sanding, so I'm either in, or entirely out ;)

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Waikoloa60 t1_ja2actb wrote

Do you have a closet you can use to experiment? Sand one wall without painting and paint the other without sanding. See what look you prefer and if it's worth the extra effort. If there's a big difference in colors, especially going from dark to light, you may want to prime first.

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alwaysfunnyinjp t1_ja30klo wrote

When in the process , you see every little thing, once you’ve painted it and moved in and all, you love it and the little details will slightly disappear in your mind .

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TootsNYC t1_ja33yf8 wrote

Wash with trisodium phosphate ((TSP) first

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SkepticlosFailed t1_ja35voa wrote

Just learning the term I used for a very thin layer of plaster is not a scratch coat... Anyway, if you want smooth walls, I'd suggest 2 very thin skim coats, one vertical, one horizontal. It will sound like scratching the wall. Sand before and after, then prime.

Maybe you could just use self-levelling paint for a smoother finish, but you'll always see the roller nap if you look hard enough

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nickypeter1999 t1_ja76s2h wrote

If you sand down and don’t do it properly, you are risking on leaving the wall not levelled up. Be careful specially if sanding down with machine.

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Few-Opinion5223 t1_j9zj1mb wrote

To achieve a nice smooth finish, it's essential to sand to help prepare the area for painting application, by sanding you are removing imperfections (also known as pimples), creating a nice smooth finish while at the same time adding adhesion by developing small, rough ridges for the paint to stick to.

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Iamnotericforeman t1_j9zqzj2 wrote

Use a pole sander. It will make it easier for walls. There always seem to be some rou spots that you’ll notice after you paint if you don’t sand.

Pole sander is not a person from Poland who does the work for you!

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