Filler

Filler is the last finishing material before paint. It fills holes left by nails and wall plugs, fine cracksCrackA split or gap in render, concrete, a wall, a coating or wood. Fine cracks are usually only on the surface; ones that grow, keep reopening or run diagonally need attention., scrapes and joints, and is spread with a filling knife in thin layers. For walls there are also skimming fillers that go over the whole surface, and for wood there are special wood fillers.

Once it has dried, the filler is sandedSandingSmoothing a surface with sandpaper or a power sander to remove bumps, loose old paint or gloss, so the new paint or varnish grips well and comes out smooth. so it does not show under the paint. Filled patches soak up paint differently from the rest of the wall, so they are usually primedPrimerThe thin first coat that goes on before the main material. It binds dust, seals the pores and helps paint or waterproofing stick firmly. before the final coats.

Filler does not replace renderRender (plaster)A layer of mortar (sand, cement or lime, and water) spread over brick or concrete to give a wall a straight, sound surface ready for paint or tiles.. It fixes small defects, not hollow or crumbling render. And if a crack keeps opening up again, filling it only hides it for a while; the cause has to be found.