Painting both 'new' and 'old' interior walls

random_banter · 23-06-2022 10:52am #1

We bought a wreck of a house and have been renovating it for the last 6 months. Finally we are getting close to the end so the next big conversation is about paint!

I've lots of experience actually painting but this tended to be on walls with existing coats of paint. I need to understand a little more about how to treat the new walls in this house as I want to make sure I do as good a job as possible, and we can't afford a professional.

There are two kinds of walls we'll need to paint:

1 - Freshly plastered walls - we have had the internal sides of our external walls dry lined and these will skimmed by a plasterer, so they will be like new. I am guessing I would need to start with a primer on these walls, then an undercoat of white and then possibly 2 coats of chosen colour. But there are so many kinds of primer - does anyone have any recommendations on which one would be appropriate?

2 - Older walls, internal which we have stripped the wallpaper from. These walls are relatively damaged due to removing the wallpaper, original skim pulled off in places but not many huge holes in the existing plaster. The theory here is that we could lightly sand down these walls with an electric sander to smooth them and then apply primer before painting them. Would anyone have experience with this kind of job and what sort of primer would do?

So my questions really are -

Primer for brand new plaster, to go under an undercoat and paint - any recommendations?
Primer for old walls which will be sanded smooth - any recommendations? Perhaps one brand would do both. I'm just so confused by the number of primers out there.
As an undercoat, is any basic white Dulux suitable?

Thanks so much to any boardsies who would be willing to share knowledge in this area. :)

C. Eastwood · 23-06-2022 3:58pm

https://www.boards.ie/discussion/2058251412/painting-both-new-and-old-interior-walls

I have always coated new hardwall plaster with 2 coats of the Matt Emulsion paint. I have never used primer. I do not thin out the emulsion.

On new plastered walls you could use eggshell emulsion paint or vinyl emulsion.

On old walls I would only use Matt Emulsion.

The brand you mentioned is an excellent quality paint.

With the old walls. Remove all the wallpaper with a steamer and scraper. Lightly sand down only rough areas on the surface.

Coat with 1 coat of the Matt emulsion and use internal Polyfilla to fill where necessary. Apply a second coat of emulsion. Ensure the polyfilla is not projecting beyond the surface. It’s best to fill and let dry and apply more polyfilla - f you leave the polyfilla project out - it is more work to sandpaper it off.

With natural timber, before painting- you Must apply Patent Knotting x 2 coats over each and every Knot. If you do not do this the resin in the knots will seep out/ burn out through the paint, in the form of brown staining.

Then over the patent knotting apply one coat of primer, Fill and sand over nail holes etc. Apply 1 coat of Undercoat and 1 coat of Matt or Satin or Gloss paint. The brand you mentioned is an excellent paint for woodwork. You will need to decide to use Oil Paint or Waterbased Paint for the timber.

If in doubt complete a small section first to help you to decide.

Always purchase the best of equipment brushes etc, including a Scraper an a Filler. Remember that Professional Painters & Decorators do not / could not work with inferior equipment.

romaderwdcsax · 23-06-2022 10:58pm

Always thin out the primer coat on bare plaster, otherwise you will have problems down the line. Apply a coat of primer, primer of Dulux Matt thinned out by approx 20% water, then 2 coats of your chosen colour and finish.

For the old walls that were previously papered. Remove all paper, wash down walls after removal of paper with sugar soap to remove the paste residue. Sand walls, then prime. My personal preference for this job would be Zinsser coverstain or fleetwood blox it. Two excellent primers. After priming, fill everything that needs to be filled, and then 2 coats of your chosen colour and finish.

A thinned out Dulux white Matt is perfectly ok for the newly plastered walls but with the older walls I would spend the extra few quid on one of the above mentioned primers to give you a very sound surface to work on, especially if the older walls were painted prior to the paper being put up.

random_banter · 25-06-2022 7:53pm

Thanks both, really comprehensive advice which is much appreciated by this newbie.

awec · 25-06-2022 8:15pm

On a related subject, @C. Eastwood we have natural wood in our house that was clearly not treated with the patent knotting prior to painting (some door frames), so we have the brown knot stains.

If I paint over this in future, can I just put the patent knot over the existing layer of paint, or do I need to sand this back to bare wood first?

C. Eastwood · 25-06-2022 11:21pm

https://www.boards.ie/discussion/comment/119249581#Comment_119249581

awec

I do not know what will happen if you apply the Patent Knotting over the existing paint. I would not do that.

When a mistake is made I always go back to the stage before the mistake is made.

It is unbelievable that qualified Painters & Decorators will not apply 2 Coats of Patent Knotting on all knots on natural timber. It only takes a few minutes to apply it. It is every cheap.

I recommend sanding off the existing stained paint with a mild sander, back down to the wood/knot. I would use an Orbital Sander with fine sandpaper so as not to damage the surface of the wood.

Then apply 1 coat of Patent Knotting and let it dry. Read the instructions on the container. Apply the second coat.

Clean the area with a cloth with and white spirits. Allow it to dry.

Give the timber a coat of Undercoat pain. If where you sanded is causing and indent in the surface, fill it with Internal Polyfilla. Sand it down by hand with fine sandpaper on a hard sanding block ( piece of timber will do).

When the surface is perfect, coat the entire surface with Undercoat.

Finish with a coat of Matt or Satin. ( or Gloss). I prefer Satin finish coat.

Do one door frame first to learn.

Patent Knotting is a Shellac solvent. Buy a small cheap brush. To clean the brush you will need Solvent Thinners. White spirits will not work.

Painting both 'new' and 'old' interior walls

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