How to plaster internal corners

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How to plaster internal corners

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Project Overview

Trowelling internal plaster corners is a great plastering skill to learn. It’s important to know if you want to plaster a room yourself. We’ll teach you how to fill and reinforce the gaps. You’ll also learn how to give the plaster a smooth finish and get it ready for painting.
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Man Cutting Tape
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How to cut paper tape

A quick and precise way to cut plaster tape is to use your paint scraper. Simply roll the tape out into position, hold the blade of your scraper on your cut point and pull the tape roll away. The blade cuts the tape and gives you a perfect edge.

Step by Step Instructions

1 Fill the gaps in the internal plaster corner
2 Reinforce the internal plaster corner with paper tape
3 Apply a top coat to the internal plaster corner
  • Step 1. Fill the gaps in the internal plaster corner

    Mix some plaster base coat in a bucket until it has the consistency of toothpaste. Then use your scraper to fill the corner gap between the plaster walls. Make sure you scrape off any excess. Once the base coat is dry, use the scraper blade to take off any small ridges on the base coat.
  • Step 2. Reinforce the internal plaster corner with paper tape

    Cut a piece of paper tape to the height of your wall. There will be a crease running down the centre of the tape. Use this to fold the tape in half. Now apply a thin coat of plaster base coat to both sides of the internal corner and press the tape over the top. Once the tape is in place, use your scraper to flatten it onto the wall, squeezing out any excess base coat. Then leave the plaster to dry.
  • Step 3. Apply a top coat to the internal plaster corner

    Use your paint scraper to apply a top coat of plaster on both corner faces. Then run an internal corner plaster tool over the top coat to give it a smooth finish. Now leave the top coat to dry, give it a light hand sand and then it will be ready to paint.

Tools and Materials


  • Buckets
  • Dust mask
  • Internal corner plaster tool
  • Ladder
  • Paint scraper
  • Safety glasses
  • Sandpaper
  • Sanding block


  • Paper tape
  • Plaster base compound
  • Plaster top coat

Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer or visit our Health & Safety page. You can also use a simple test kit from Bunnings to indicate the presence of lead-based paint.
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