I have cracks in my lime plaster/render how do I fill these?

I have cracks in my lime plaster/render how do I fill these?

If you have cracks internally or externally – slightly open up the crack and you can use casein filler.

The surfaces should be clean and grease-free. Water-soluble old coats of distempers or lime-paints must be removed. Any loose material should be brushed off. 1 kg of Filler should be mixed with 150 ml water until a lump-free paste is obtained. If necessary add some water during application. Apply the ready-mixed filler to create an even surface. If necessary level-out deep holes and cracks a second time. Leave for 8 hours and then sand back flush.

Externally if you are applying a silicate paint to renders use Beeck’s silicate filler to fill cracks. Use 1 or 2 coats of Quartz filler (painted on) to even patchy backgrounds and cover fine hairline cracks before applying the Beeckosil or Renosil masonry paint.

For internal cracks you can use Ty-Mawr general purpose filler - see technical sheet for guidance.

For internal top coating/ skimming over old plasters - Provide a physical key and control suction by damping down. Use Ecomortar R50 which can be trowelled down smooth or finished with a sponge finish for a sandy texture whichever suits the situation. Use R100 over painted surfaces, first ensuring the paint is sound.

You can re-skim, if by an experienced lime plasterer, with Ty-Mawr internal finish plaster with fibre. Again the same rules apply – provide a physical key and control suction by damping down. The benefit of R50 is it is a gauged product and has no shrinkage whereas our Ty-Mawr internal finish plaster has the potential to crack if not applied carefully with due consideration to the substrate.