Sanding Door Frames Ready for Painting

Sanding door frames is an often overlooked but important part of the preparation process for painting doors and door frames.

However, there are a number of factors you will need to be aware of before sanding your door frames. This includes the condition of the timber as well as the condition of the paint currently on the door frames.

As a professional decorator with 20 years of experience, sanding door frames is part and parcel of painting interiors and the aim of this DIY guide is to share my knowledge so that you ensure you prepare the substrate properly before painting.

With that being said, here’s my guide to sanding door frames.

How to Sand Door Frames

Sanding door frames should be a fairly simple process depending on the condition of your current door frames. I’ve put together this guide assuming that your door frames are in a pretty bad condition. Of course, if your door frames are already sound or have yet to be painted then you can simply skip some steps listed below.

Sanding Previously Painted Door Frames

Tools for the job:

  • Scraper
  • 120, 180, and 240-grade sandpaper
  • Wood filler
  1. Check the condition of the paint

    Before sanding, it's important to check on the condition of the existing paint film. If it's sound, you don't have too much to worry about. If the door frame was previously painted in gloss or satinwood and is peeling then you will need to use 3 different sandpaper grades to ensure the top coats adhere to the surface.

  2. Scrape away the peeling paint

    If you have peeling paint, you will need to use a scraper to remove any loose paint. In general, even if the current paint system looks ok, inspect and remove any nibs with the scraper.

  3. Sand the surface with 120-grade sandpaper

    You should use 120-grade sandpaper, which is on the medium-fine scale, to remove any loose paint. This sandpaper grade is tough enough to remove loose paint without damaging the softwood that your door frames are likely made out of.

  4. Sand the frames with 180-grade sandpaper

    You can now use 180-grit sandpaper just to smoothen up the surface and remove any traces of the previous coarser sanding.

  5. Fill any holes or cracks

    Use a wood filler (preferably something good quality like Toupret wood filler) to fill any cracks or holes on the surface of the frames. If the frames are in good condition, you can skip this step.

  6. Rub down with 240-grade sandpaper

    Once the filler has dried, rub down the door frames with 240-grade sandpaper. 240-grit sandpaper is an extra fine sandpaper that will leave a smooth finish yet ensures future paint systems adhere properly to the surface.

  7. Dust down

    Your sanding journey has come to an end! All you need to do now is dust down the surface to ensure there's no dust present when you move on to painting the surface.

Sanding Unpainted Door Frames

Sanding unpainted door frames follows a slightly different process as the one outlined above but is still fairly easy to follow for a DIYer. Here’s what you need to do to ensure the surface is prepared properly before decoration…

Tools for the job:

  • Fine glass paper
  • Stripping knife
  • Hammer
  • Wood filler
  • Dusting brush
  1. Ensure the surface is sound

    Inspect the surface for any defects and loose debris such as plaster. Use a stripping knife to remove any nibs left on the surface of the frames.

  2. Hammer in protruding nails

    If you have any protruding nails or pins present on your door frames, use a hammer to hammer them below the surface.

  3. Fill the holes

    Use a good quality wood filler such as Toupret wood filler to fill the holes left behind from when you hammered the protruding nails below the surface.

  4. Abrade the door frames with fine glass paper

    Using a 240-grit fine glass paper, lightly sand the door frames, ensuring that you sand diagonally across the grain.

  5. Very lightly sand along the grain

    Using minimal force, use the glass paper to sand along the line of the grain. This should ensure that your paint system adheres properly to the lightly-scuffed surface. It's worth bearing in mind that if you plan to decorate your door frames with a stain or varnish, you should avoid sanding across the grain as the glass paper marks will be clearly visible and won't look great!

Best Sander for Door Frames

As a professional decorator, I will typically use a dustless setup and have access to both a Mirka and Festool. For jobs such as sanding door frames I will typically use the Festool as I find it’s better at dealing with softwood sanding.

Of course, if you’re not a professional and don’t want to make such a big investment I would honestly recommend just using regular hand sandpaper and wrapping it around a block of some sort.

Do You Need to Sand Door Frames Before Painting?

I would always recommend sanding door frames before painting them. This is especially important if you’re going to be painting over previously painted surfaces as the paint will struggle to adhere to the previous coats otherwise.

It’s also important to sand door frames that have yet to be painted as the surface of the softwood will likely be very smooth and won’t have much of a key for your paint to adhere to.

By not sanding door frames before painting, you open yourself up to all sorts of future paint defects.