Uneven grout colour

[jacoscar]

Hi all, I’ve done my first DIY tiling job and I’m pretty happy apart from the grouting. I used Mapei Flexible Wall & Floor Grout Silver Grey.
I did one mix, half of the room, then another mix and the other half of the room. The first half has some uneven color (it’s very dark in some places), while the second half is a very uniform light grey color.
I used the exact same waterowder ratio for both mixes (I used a kitchen scale).
There were some adhesive residues but they were evenly distributed in both halves of the room.
What have I done wrong?
What could be the reason?

 

[foxhole]

Tile cement not removed from grout lines gives a darker appearance to any grout on top.Darker grout is best on floors, it always ends up that way.

 

[yorksbuilder]

Maybe you didn't mix the grout in the bag enough before measuring it out? I always squeeze the bag and shake well before opening it to ensure the powder is properly uniformly mixed

 

[jacoscar]

Maybe you didn't mix the grout in the bag enough before measuring it out? I always squeeze the bag and shake well before opening it to ensure the powder is properly uniformly mixed

No, I didn’t mix it in the bag. But even so, I would expect two different shades between the two halves of the room, not two shades within the first half.

 

[yorksbuilder]

I think then its likely to be as Foxhole says. Anyway overall your grout looks good!