Problem
Floor different colour than the walls. Most commonly the floor ends up darker than the wall.
Possible Causes
- Floor over exposed
- Too long left between finishing the walls and starting the floor. This causes a cold joint to form where the wet floor joins to the drier walls.
- Trowelling the floor at ninety degrees to the direction the wall was trowelled.
- A drier mix was used on the floor. The oxide to water ratio has an effect on the final colour. Drier mixes produce darker colours and vice versa.
- Material from two separate batches was used.
Possible Solutions
Acid wash the pool again paying particular attention to blending in the floor to the walls. This may be achieved a number of ways.
- It may be possible to expose more of the coloured aggregate in the walls thereby darkening them and providing a better match, and/or;
- Polishing the joint line and the floor. Polishing slightly lightens the surface as glaze is removed from the coloured aggregate.
After performing either of these procedures it pays to pressure wash the entire surface, as this will remove excess oxide. Doing so helps to even out colour variations.
Whilst it may not be possible to completely eliminate all the colour variation, the solution described above will certainly help. Over time the discrepancy will reduce of its own accord as the cement sits immersed in water and fully hydrates.
Future Prevention
Pay particular attention when acid washing that acid is not allowed to sit on the floor of the pool.
Ensure that a wet edge is maintained at all times. To do so consider:
- Ensuring adequate trowel hands are available.
- Reducing the length of the wet edge by working across the pool rather than doing the walls first then the floor.
- Avoiding cross trowelling at joins, i.e. when joining the walls to the floor, attempt to trowel the floor in the same direction as the walls.
- Ensure batches of stock are mixed evenly if mixing from different production dates.