Wash the Walls, Really?

Dear Home Ec 10,

My living room desperately needs to be painted and I’ve rounded up a few friends willing to help sell their time for beer and pizza.  I really want to do this right, is it true that I have to wash the walls before I paint?
Short-Cut Shelby


Heather says:

Look at it this way, washing the walls can save you money and time in this project. Seriously. Anytime you cook, open the window, spray hair spray, etc. particles that can adhere to your walls, do. Over time this creates a thin, mostly invisible but greasy layer of dirt and dust on your walls. This layer of funk isn’t evenly distributed, making it difficult to evenly apply your new coat of paint.

Any degreaser will do, but if you want the job to go quickly with little elbow grease, check out TSP or Trisodium Phosphate. This chemical, when mixed with water has a high enough pH to saponify grease. This simply means that it turns the grease on your walls into soap. TSP used to be included in both laundry and dishwasher detergent until it was found that algae really loved all the extra phosphorous in the water supply. Since then it has been phased out of detergents, but it’s still appropriate for small applications.

TSP is not your, gee-the-walls-look-a-bit-dirty-but-I’m-not-going-to-paint wall wash. Trisodium Phosphate etches or chemically scratches the paint surface while it strips away the grease. If you’re getting ready to apply a fresh coat of paint, this is pure win as it gives the new paint better adherence.

how to take care of your walls

Click the picture for more tips!

I strongly urge you to read and follow the directions and safety precautions. While the highly alkaline nature of TSP makes it fabulous for stripping grease off of walls, it also can cause chemical burns if it gets on your skin. Keep it in perspective, chlorine bleach also causes chemical burns when used inappropriately.

In other words, wear gloves while using the TSP according to the label directions.

You should be able to find TSP at home-improvement stores.

Good luck!

Washing walls before painting helps the new paint adhere better, saving time and effort

Send your domestic queries to helpme@home-ec101.com.


  1. Bonnie on February 2, 2014 at 12:04 am

    I have washed my mobile home walls which are that fabricated walls with tsp, worked great! It got the most stubberned stains along with a “scrubby”. They look dull now should I rince with just water or will something like vinegar/water work?

  2. Scott Webster on April 22, 2011 at 6:50 am

    How do you avoid TSP coming onto your skin? I do agree that washing the walls is necessary but should we use chemicals if this is just living room, not kitchen?

    Indianapolis Painting Services

    • Katie on May 24, 2013 at 12:44 am

      Wear gloves! Like yellow kitchen gloves, and cuff the ends, so when you lift your arms up the water doesn’t run down your arms. Works great;although I can say my mother & Nana never wear/wore gloves and they don’t have any bad side effects from using tsp. we wash our walls maybe once or twice a year and I’ve never had a reaction. The only annoying thing is your skin feels soapy, like you’re rinsing with head water? I just make sure I really clean my skin afterwards and put on some lotion.
      Btw love this site, answered so many questions quickly and effectively!

  3. rin-ill on January 31, 2011 at 4:16 am

    ugh, i never thought about sanding. i wanted to repaint our bathrooms… so much work!

  4. Woodson painting on February 3, 2010 at 5:10 pm

    Great advice! Yet another great read. Thanks 🙂

  5. Letterpress on February 2, 2010 at 3:50 am

    Have you ever tried washing that stuff off? Those chemicals alone will keep the paint from sticking, and frankly, it is so last year.

    Come over to the Primer True Believers Side. Go down to HDepot and get a gallon or two of primer (I know you can tint them, but I mostly use white so I can use it under everything) and paint your walls first with the primer. Use rubber gloves as the primer will stick to you too. Then paint. It's unbelievable how easy it is and how wonderful it is. I've painted bathrooms, kitchens (twice, because I changed the color after 8 years), bedrooms, hallways, living rooms, the laundry room in the garage, and it all sticks fine every time. The hallways are going on 15 years and still look just as good as new (although the paint I used was satin finish–no flat matte except in low traffic areas for me). I've painted my cottage-cheese ceilings with primer, then painted over those (huge improvement).

    Yay for primer–the miracle!

    • HeatherSolos on February 2, 2010 at 11:18 am

      Thank you for your advice.

    • imchrisann on October 21, 2015 at 1:03 pm

      I was wondering about the rinsing aspect of this stuff. That’s great for outdoor painting, but for interior use, how the heck do you “rinse” walls? Also when “rinsing” how do you know it’s all off?!

      Thanks for the primer tip!

  6. mom, again on January 29, 2010 at 4:58 am

    Right, Kim! If the walls were painted with any kind of latex, even matte finish, you'll need to either sand the walls, or more likely you can rely on the etching effect of the TSP /fake TSP to do the same job. It will make all the difference. Without it, you will paint and paint and paint and still get tiny pinholes opening up to reveal the previous color. You might end up, like us, using twice as much paint putting on repeated coats in an attempt to overcome this. (pale blue over golden yellow. 2 layers of white primer in between, and still, there are spots where I can see the yellow through 3 coats of newer paint). By the time we did the room down the hall, we'd learned about washing the wall, and one slapdash coat of primer covered the red pretty well, allowing us one coat of the pale green.

    ps I don't like that your comments page has somehow chosen my facebook ID, my real actual name, to ID me with, I'd much rather enter my own. very inconvenient to have to log out of facebook to do so.

    • HeatherSolos on January 29, 2010 at 5:28 am

      I am sorry it bothers you. If you create an actual IntenseDebate account, you have even more control over your content. The reason I installed a 3rd party comment system is this allows me to moderate the spam (which is obnoxious) away from the computer.

      Aside from that a many people like aggregating their content, whether it's a comment on my site or their facebook, Twitter, and that ilk and commenting systems like ID, Disqus, and Echo give those users the freedom to do so.

      I know that doesn't solve your issue, but I hope it makes my choice to use it more understandable.

  7. kim on January 28, 2010 at 9:36 pm

    In all my years of painting, I have only "washed" the walls once before I painted. I've always had good luck with flat (matte) paint over flat (matte) paint. However, the one room that I washed the walls had a semi-gloss paint applied (bathroom) and the new paint did NOT stick well even with the pre-cleaning.

  8. Jenn on January 28, 2010 at 4:12 pm

    There is now a tsp substitute available which may do the same job without the same dangers. It's still scary stuff but no phosphate problems. I know Home Depot carried substitutes for tsp and someone at the paint desk should be able to say if it's as effective.

    And painting, like many jobs is only 20 percent actual painting. The rest is prep. Since nobody on your team is a pro, you'll get the best, professional-looking job by laying down drop cloths, washing the walls, taping the woodwork and buying the right tools for the job. And saving most of the beer for when the job is done. 🙂

  9. Jenn on January 28, 2010 at 4:14 pm

    Oh, and absolutely rinse well if you use the real thing. I remember my mom cleaned the ceilings with it once and rinsed 3 or 4 times. You know, they should put a dye in the tsp so when you're rinsing you know the tsp is gone when the color is gone.

  10. David on January 28, 2010 at 2:51 pm

    High phosphate detergents can stimulate mold production. Primarily because a lot of the phosphate is left behind. The following article discusses that after disaster clean up, but it applies anytime you use detergents that have high phosphates: http://msucares.com/disaster/mold-june08.pdf

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