Any wall that has an external corner needs to have an angle bead fixed in place before plastering can commence. If you have a wall with no external corners then have a go at plastering this one first.
Then when you have got to grips with the basics the angle bead will be fairly straightforward.
There are two types of angle beads for forming corners:
Skim Bead For skimming only. The skim bead (also called thin coat bead) is fixed onto the corner using nails or finish plaster. If just the skim coat is being applied the wall and corner should be reasonably flat therefore the skim bead can be pushed tightly on to the corner and secured without the need for checking straightness. Do ensure the bead is pushed onto the corner firmly – checking that the edge is approximately 2-3mm away (the thickness of 2 coats of finish plaster).
For walls that need both a backing coat and skim coat.
The bead should be securely fixed to the corner using either nails or plaster. It is crucial to ensure the edge of the bead is not only straight but also not too far away from the wall – as you will be plastering up to this edge and following it. Therefore if the bead is wonky so will your wall be - so when you are fixing the bead keep checking it to ensure it is straight and upright by using a straight edge and spirit level.
As you are always working to this edge it is dictating the thickness for the whole wall therefore keep checking to make sure you will not have to apply to great a thickness of plaster to the wall.
For the same reason it does not want to be fixed too tightly onto the wall otherwise you may not have sufficient depth for your plaster.
The bead needs to be running straight and upright resulting in the very edge of the bead being away from the wall 10 -12mm or whatever thickness of plaster you intend to put on.
Edge of bead dictates thickness of plaster, that will need to be applied to the wall. The backing coat will be applied flush to this edge of the angle bead. Once the wall has been floated it will be necessary to recess this backing coat by approximately 2mm just at the very end by scraping it back with the trowel. This will allow the skim coat to finish flush with the edge of the bead
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