G
Gazzer
To be fair Neale, it may be the first time he's used black grout. Efflorescence can occur with any coloured grout but it's not always visable.
My BAL Ebony efflorescence free grout is still holding up well.
But for a "Tiler" to say he or she has never heard of Efflorescence is a bit suspect to me. This "Tiler" is playing with £1000 worth of tiles and i would want him/her to know the trade.
We are not talking about a little known subject here but of a major problem.
Yes it can affect all grouts but the darker ones tend to show the problem more so.
Also Yes your "BAL Ebony efflorescence free grout" should hold up well....the clue is "efflorescence free".