How To Paint Over Grease

Grease stains on painted walls and ceilings aren’t exactly a major health hazard, but they do look unsightly and detract from the overall appearance of a room.  Painting over grease isn’t difficult, but if you don’t follow the simple process correctly, the grease marks will continue to reappear through your nice new emulsion.

Sometimes I’m asked in my role as a professional decorator, “Can’t you just paint over it with something?” (Especially by landlords after a quick job!).  Well, to be honest it’s a false economy, because doing the job properly doesn’t actually cost much more in terms of time or money, whereas failing to do the job properly only leads to the job having to be redone in the not-too-distant future, because the grease stains will just reappear through the emulsion.

Grease – usually splashes of cooking oil or fat – is most frequently a problem for decorators in kitchens, but occasionally (as I found out last week!) in dining rooms too. Elsewhere in the home, I guess food-related accidents can happen, but hopefully not too frequently.

However, other pet-hates amongst decorators – Blu-Tac and wax crayons – can be found anywhere else in the home, and I follow the same simple process to deal with the greasy marks that Blu-Tac and wax crayons can leave behind on walls and ceilings. 

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Painting Over Grease – Step 1:

Clean Off as Much Grease as Possible

The first step is to remove as much grease as possible. If there are deposits of grease (or Blu-Tac) still on the surface, remove them with a scraper, wipe onto tissue paper, and dispose of it in the household waste.

I then usually degrease the area; you can use a detergent solution (such as washing up liquid in warm water), an industrial cleaner such as a dilute solution of Virosol, or a proprietary degreaser such as Zinsser Universal Degreaser & Cleanser, which seems to be the most affective agent for removing grease stains. All you do is spray it onto the grease, wait a minute or so, then wipe it off with a damp cloth. Open a window because it is quite strong.

Painting Over Grease – Step 2:

Block The Stain

 

As stated previously, if you simply paint over grease stains with a water-based emulsion paint, the stains will come back through. Grease being an oil simply bleeds through your water-based emulsion and sits on top.

So, you need to apply a coat or two of a primer that will stick to the grease and stop it reappearing.  There are many types of stain-blocking primer available these days; I have to be honest; I haven’t tried them all out on grease stains, but the ones I’ve had most success with have been shellac-based primers.

The three most well-known brands are probably Zinsser B-I-N, HB42 “PS1”, and Fiddes “Full Stop”; they are all similar products, and every professional decorator carries one or other of them somewhere in his or her van.

My personal favourite is Fiddes Full Stop. It seems to be easier to use, better opacity, and better at blocking stains like grease. It has slightly less odour too, making it more pleasant to apply.

So, a quick coat of shellac-based primer, wait for it for it to dry (this typically takes 20-30 minutes – time for a cuppa!), and then you’re ready to paint over with your chosen emulsion.

A lot of decorators I know use oil-based undercoat for blocking stains like grease rather than a shellac-based primer; there’s nothing wrong with this approach, it certainly works, and saves you having to buy a tin of primer if you don’t already have one. However, oil-based undercoat is going to take hours to dry, meaning you must find something else to do in the meantime, whereas shellac-based primer dries in a fraction of the time, which is why I prefer it personally.

 

Three Top Tips When Using Shellac-Based Primer to Paint Over Grease:

 

  • When you buy a tin of shellac-based primer, buy a bottle of methylated spirit at the same time – it’s the best thing for cleaning out your brush afterwards (white spirit won’t work) – or just use an old brush that you are happy to throw away afterwards
  • Stir the product thoroughly every time you open the tin. Giving it a quick shake isn’t enough – the solids in the paint tend to sink to the bottom of the tin and form a sticky mass – you need to stir thoroughly to make sure these are properly mixed in the paint to get the best result.
  • Don’t be surprised if, when you emulsion your wall or ceiling, the areas that you treated with the primer take longer to dry. Paint dries by both evaporation and absorption, and shellac-based primers form a barrier which stops the grease stain bleeding through, but also reduces the ability of the plaster to absorb moisture from the paint.  Just make sure you allow plenty of time for your first coat of emulsion to dry thoroughly all over before applying a second.
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Painting Over Grease – Step 3:

Paint!

 

Yes, it really is that simple. Once you’ve cleaned the grease as best you can, and thoroughly blocked the grease stain with a suitable primer, you’re ready to paint your walls and/or ceilings with your chosen emulsion.

Remember though, that if you’re painting a room where grease stains have already occurred, there’s a good chance that the same thing might happen again, so I’d recommend that you choose a good quality trade paint that has some resistance to staining and can be cleaned/scrubbed if necessary to remove any future stains when they happen.

A personal favourite of mine is the Crown Clean Extreme range, but there are plenty of excellent trade emulsions available; for example, there is some great advice online here on the best choices of paints for kitchens.

Clean Extreme has always been my favourite for a few reasons. It is reasonably priced, easy to use, has good opacity, leaves a brilliant finish, and it’s very durable. This means that if you splash your walls or ceilings again, it will simply wipe off with a wet cloth and some washing up liquid.

You can also buy it in matt, eggshell, or anti-mould, so just get the one that best suits the room you’re painting.

Final Thoughts

 

So there you go, it really is that simple to paint over grease stains (including cooking fat, Blu-Tac and wax crayons) in your home; the extra time needed to carry out a little prep work and clean and prime the stained area properly is minimal in the grand scheme of things, and it seems silly to skip these simple steps and risk ruining your newly decorated room, just for the sake of saving an hour’s work.

How To Paint over Grease Stains for Decorators Forum UK

Robin Gofton – Wokingham Decorating Services

Posted Sep 12, 2023 | 3 comments

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3 Comments

  1. Daniel Jobson

    Do you have any recommendations of a clear coat to apply once painted, to prevent further grease stains and for easy cleaning?

    Reply
    • Mike Cupit

      Polyvine Decorators Varnish is what you want

      Reply
      • Daniel Jobson

        Great, thanks for the reply.
        I found Ronseal Stain Guard Clear Coat earlier today, which looks to be the same sort of stuff. I’ll give your recommendation a go. Thanks again

        Reply

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