Greasy or oily patches on a solid floor in a garage, shed, cellar or kitchen, must be removed before you lay floor coverings. Grease can build up to such a level that it becomes a hazardard, you should apply a concrete paint or a proprietary grease removing solution, which you can buy from motor accessory shops. Scrape the floor to remove as much grease and dirt as possible and brush on grease remover solution until the surface appears thoroughly wet. Leave for up to 15 minutes for the grease to soften and agitate it with a stiff brush from time to time. If necessary, apply more solution until the grease stain takes on a soap-like appearance. Wash with water and brush the floor; repeat the treatment if the stain remains after the floor has dried out.
This can be cured with a concrete hardening and dustproofing liquid. Sweep the floor or vacuum it clean if possible – and apply the liquid with a brush, according to manufacturer’s instructions (two coats may be required). You can use a PVA bonding agent diluted with water, but allow the treatment to dry before subjecting it to normal traffic. According to the wear the floor receives, the treatment may have to be repeated every one or two years. If you need a more durable coloured finish for a garage, store or outside WC, you can apply a brush-on floor sealing compound to give a tough, dustproof coating which is impervious to water and oil.