How to plaster over mortar repairs?

[Madfish]

Hi all, I am helping renovate a 100 yr old home for my son. We have got large cracks where we have repaired stonework to considerable depth, digging out old mortar and remortaring, sometimes through to the next room. The wall is made of stones and covered with a hard plaster. So what is the best product and process to now cover these mortar repairs ,some which are over 30cm wide.

[MitchellMc]

Welcome to the Bunnings Workshop community @Madfish. It's brilliant to have you join us, and many thanks for your question about repairing a wall.

If the original surface was finished with hardwall plaster, it would be best to use the same material to match the existing wall. 

Start by ensuring all the mortar repairs are fully cured and free from loose debris or dust, which can be removed with a stiff brush. To help the new plaster adhere to the repaired areas, apply a suitable bonding agent across the mortar patches and surrounding surface. Once the bonding agent has dried, mix your hard plaster according to the manufacturer’s instructions and apply it in layers, starting with a base coat to level out the surface. Smooth this layer with a trowel, ensuring it blends seamlessly into the edges of the existing plaster. Once the base coat has partially set, apply a thin finishing coat and smooth it out to match the texture of the surrounding wall. Allow the plaster to cure completely before sanding lightly and preparing the surface for painting.

Here's a helpful step-by-step guide: How to hard plaster a brick wall.

Please let me know if you have any questions.

Mitchell
 

[Madfish]

Hi Mitchell 

The attached photo shows you where we are up to. 

[MitchellMc]

Hi @Madfish,

That's about what I had in mind. As long as the cement is lower than the surrounding area then you'd be fine to overcoat it with the hardwall plaster.

Mitchell