So decided to redecorate a bedroom ourselves.

We removed wallpaper, scrubbed, sanded, cleaned, primed (Zinsser B-I-N White Multi-surface Matt Primer), skimmed (Make Good Plasterboard Jointing, filling & finishing compound) and one coat of primer/undercoat (Dulux Universal White Multi-surface Primer & undercoat). My issue is I have a few areas where I can see 'steps' from where I've skimmed, my fault for not sanding well enough in these areas.

Can I use joint compound again and skim on top of the primer/undercoat OR should I be doing something else? Please help. Go easy on me, I'm a rookie :) learning as I go. Thanks.

1 of the walls

  • 2
    For future reference, always use the brightest, most intense, work lights available when doing this type of work. Mar 1, 2021 at 16:09
  • 2
    ....and place that light so it's raking from the side to accentuate any problems.
    – Ecnerwal
    Mar 1, 2021 at 16:11
  • ... and I found the best raking lights to be small but intense single point lights, like from flash lights or GU10/PAR20 LED bulbs in a desk lamp or open fixture
    – P2000
    Mar 1, 2021 at 20:05

2 Answers 2


Yes you can overcoat the primer with more joint compound.

If you have some left just use that, but if you need to purchase more consider topping mud. Topping mud is made for feathering places like you have and it sands just a bit easier.

In either case standard joint compound or topping mud will work on a primed surface.

Remember to prime the freshly mudded areas or it will absorb the paint and look different.

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    Yes, and remember (at least for a DIY-er like me) that the priming stage commonly reveals problems not visible earlier, so it's very normal to fix areas after priming
    – P2000
    Mar 1, 2021 at 20:01
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    You can also thin all purpose with a bit of water for a smoother easier to feather finish
    – redlude97
    Mar 1, 2021 at 22:53
  • Thanks for your advice and the light tip. I bought a Mains-powered LED Work light 700lm. Now I'll be able to see ALL the imperfections in great detail :) but be able to fix it properly.
    – John F
    Mar 2, 2021 at 13:05

Yes you can. And you need to sand much much better along the edges - I can see this is not the only issue on that wall. Honestly the whole wall needs to be basically "remudded". I see a huge drywall seam where it is obvious you didn't put enough mud. In other places it looks like you didn't sand enough. Honestly the wall is a bit of a wreck. You will almost certainly have to go out further than you normally would just because sanding some of the external edges will be too hard with primer over.

You are not going to be able to add just a little bit of joint compound and sand it. You was going to have to probably go a good 3-4" out in all directions and sand down evenly. Quite honestly you have more than this spot on the wall to do - this is going to be some work to get it done right.

Example is that seam - you went out maybe 3-4" on each side. A seam should have at least 8 inches on each side, and if an outside edge isn't sanded well it should be at 6-8". It was almost like the wall was mudded to cover up things and scraped off.

I am not saying any of this to be mean. I just think you need a reality check or you are going to keep doing the same thing wrong and this will take forever.

  • Thanks for your detailed feedback and honesty @DMoore. I'll admit, It is a bit of a wreck :) I only skimmed 2 times but now I know I need it thicker and wider. I'll have another go with joint compound and my new work light. What thickness of compound do you recommend doing to try and fix it and make it even?
    – John F
    Mar 2, 2021 at 13:08

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