How can I finish this poorly plastered wall?

[peader]

Hi All, 
The previous owners of our house created an extra bedroom by partitioning part of an L shaped living room.
The living room side of this wall is nice smooth plaster, however the bedroom side is awful.
It is not level, contains lots of scratches, nicks and trowel marks. This side has already been painted over.

What's the best way to get this to be a smooth surface. Is it possible to plaster over the top?

I'm going to repaint this bedroom soon and would love to fix / improve the surface of this wall first.

Thanks
Peader

[JacobZ]

Hi @peader,

A warm welcome to the Bunnings Workshop community and thank you for your question.

Grab yourself a good quality 6-inch plastering knife such as this Hyde 6" Plasterboard Joint Knife, a bucket of Gyprock CSR 2.25kg Less Mess Topping Compound and a Trojan 220 Grit Jumbo Angled Sanding Sponge.

Start by scraping the plaster with your plastering knife. The aim is to remove the obvious lines and undulations in height. This will remove paint, but this will be fixed afterwards, so don't stress too much. The one thing to be cautious of is going too close to the corner as there is a good chance there is paper tape in the corner that could get pierced by the plastering knife.

Once you have scraped back the existing plaster, add a little bit of water, about half a cup, to the topping compound and give it a good mix. You want it to be super smooth as this will give you a nicer finish when applied to the wall. You can then apply the topping compound directly over the scraped-back areas. With topping compound, you'll want to go much wider than what seems logical. The wider the application, the easier it is to feather out and conceal the undulations beneath. Aim for a patch around 300mm wide. Do your best to get it nice and smooth with the blade.

Once the first coat has dried, have a look to see if there are any small holes in the plaster. This can occur when air gets trapped in the mix and it is why you should mix the compound to ensure you get it nice and smooth before application. If there are any small holes in the patch, apply a very thin second coat to fill the holes.

Once this second coat has dried, use your sanding sponge to get everything perfectly smooth.

After sanding, brush the patch down with a soft-bristled brush to remove any remaining plaster dust and then paint it to match the surrounding areas.

This will give you a fantastically smooth wall that will conceal the average plastering efforts from the previous owner.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob