grey porcelain tiles fitted with a charcoal grout - Tile Advice

[Bellg2]

I've recently had grey porcelain tiles fitted with a charcoal grout. Unfortunately my grout hasn't turned out charcoal. Some bits are the rest has turned white/sand coloured. The company have said it's just sand coming to the surface and will go away eventually. I've paid a lot of money for something that looks like it's been down 20 year. Any advice appreciated

 

[Dave]

It loons like polymer residue, due to over washing and not removing excess water from joints. As for sand coming to the surface 😂

 

[Tazz476]

It loons like polymer residue, due to over washing and not removing excess water from joints. As for sand coming to the surface 😂

As in washing too much prior to grout drying?

 

[Dave]

As in washing too much prior to grout drying?

Whilst washing off yes.