Question We just recently completed constructing our pool and spa. Our pool builder used Mapei (North American Adhesive) 4300 grout (Smoky Coal); non-sanded (we used non-sanded because of our glass tile). We had the grout cure for at least 24 days. After we filled up the pool with water (no chemicals and the water isn't heated), and noticed that when you touch any of the grout lines, the pigment or color washes off. Our spa, in particular, is unusable because of this since you end up with black pigment all over your body if you use it. Our pool builder indicated that it may take a year before this stops happening...but I am looking for advise to address this. Will sealing help? I've attached a video to show what is happening. What is causing this? Any advise would be appreciated.
Answer Hi sorry for delay.
It seems wrong application only since a cementitious grout is normally n0t recommended in pools. Also sanded grout is recommended for small tile joints which is in MM If you waited for 24 days its has cured by that time.But normally Mapei recommends 28 days curing for cementitious grout since the temperatures are sub Zero at places.
All above are general guidelines and I am waiting for MAPEI to reply for the 4300 grout since I have not used that grout.