How to Prepare Interior Woodwork for Painting

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In this article, we’ll be looking at how to prepare interior woodwork for painting. You can use the methods described on skirting boards, window sills, architraves, bannisters, rails, doors etc.

Good preparation is key when you’re painting interior woodwork. It’s worth spending more time on this part of the process than you think you need to make sure you get a good finish.

Before you start working on any interior woodwork, it’s best to clear all the furniture out of the room. If you can’t do that, move the furniture to the middle of the room and cover it with protective sheets to protect it from spills and dust (especially from sanding). Cover your floor as well.

The first thing you want to do is to check the woodwork for cracks and holes. If you spot any, you’ll need to use some wood filler to do some minor repairs to the wood’s surface. Cracks and holes will only get bigger over time, so fixing them asap make sense.

Read the next section for instructions on how to do that. If your woodwork is free from cracks and holes, skip this section and move on to the next one.

Use wood filler to fill holes and cracks in interior wood

If you don’t already have some, buy suitable wood filler and a filling knife (a putty knife or paint scraper work just as well) from your local DIY store or online. Using the filling knife, liberally apply the wood filler to the damaged woodwork taking care to fill the holes and cracks. This is your first pass, so don’t focus on getting a perfect finish. Concentrate on filling the holes. Once it’s almost dry, use a slightly stiffer filler knife (or similar tool) to remove the excess filler.

Some wood filler dries in an hour so you won’t have to wait long. The wood filler packaging will provide you with clear instructions on how to use it for the best results.

Once the filler’s dry, use medium- or fine-grain sandpaper wrapped around an off-cut of timber or a purpose-made sanding block to sand it down to create a smooth finish. You may find that you need to start the sanding process with medium- or coarse-grain sandpaper and gradually work your way down to fine-grain. Remember to always sand wood with the grain – never against it.

Before you start sanding, open the window (if you have one) for ventilation. And don’t forget to wear a face mask so you don’t breathe in the dust. You might also want to wear safety glasses to protect your eyes.

Preparing painted wood for repainting

If your wood was painted before, you need to sand it down with fine-grain sandpaper to create a key for the new paint stick to. Go over each area of the wood with your sandpaper to remove part of the top layer of paint, but don’t apply too much pressure as you’ll remove too much. Gentle rubbing works best. You just want to create a key for the new paint to stick to, not take the wood down to the grain.

Make sure you get into all the recesses and remove loose or flaky paint and bubbles from previous coatings.

Hand-sanding is best for smaller areas and things like skirting boards, bannister rails and architraves. You could use an electric sander on larger skirting boards, window sills and doors.

Wash down interior woodwork before painting

When the sanding is complete, you’ll need to get rid of any bits of dust stuck to the woodwork. You can use a vacuum cleaner with a brush-type accessory so you don’t damage the wood, or a dusting brush.

When you’re confident you’ve removed as much of the dust as possible, generously apply sugar soap to the wood’s surface making sure you cover every part of it. Sugar soap contains a degreasing agent for cleaning painted surfaces and is generally recommended by most decorators. You can buy it in a spray bottle for easy application.

Once you’ve applied enough sugar soap, use a sponge to wash down the surface. This will remove the last of the dust and grease.

Finally, using a clean rag dipped in warm water, wash off the sugar soap and allow 15-20 minutes for the wood’s surface to completely dry.

Now your wood is ready for painting!

How to paint new wood for use indoors

New wood should have any knots sealed with knotting compound to prevent the wood resin from staining the paintwork in the future. You can buy knotting compound (sometimes called knotting solution) from most good DIY stores for around £5 to £6.

One coat might be enough, but to be on the safe side, apply two coats to each knot.

Once the knotting solution has dried, the wood should be lightly sanded down using fine-grain sandpaper, cleaned off with a damp cloth and then a coat or two of wood primer applied prior to the topcoat.

After you’ve completed this, you’re ready to start painting. And when you’re done doing that, check out my guide for taking proper care of, and cleaning paintbrushes so they last a long time.

Tools needed to prepare interior woodwork for painting

  • Sandpaper – various grades
  • Sanding block or a small piece of timber to use as a DIY sanding block
  • Sander (for heavy-duty sanding, you might need a belt sander)
  • Dustsheet(s)
  • Face mask
  • Safety glasses
  • Wood filler
  • Filling knife/putty knife/scraper
  • Knotting compound
  • Vacuum cleaner
  • Sugar soap
  • Sponge
  • Rag
  • Warm water