Mid grey grout gone white at someparts?

[Elite criteria]

Hi

So first time grouting

Iv got mapei ultacolor mid grey

I got the paste to a toothpaste texture so seemed ok

Once dried this morning it itsnt really mid grey

I think maybe when i went over it with a sponge maybe i wet the grout too much?

Iv now taken one line out and dabbed a new grout without too much waiting to see

Now im
Thinking i read if you rub olive oil over the white part the original color comes out

See some pics

They look dark at parts because i tried going over with water to wash out white

 

[Elite criteria]

Yh i think maybe when i went over it i maybe didnt have a damp
Dry sponge

 

[Elite criteria]

Ivgot one line i did this morning will reportback

I did go over with damp but any excess i wiped away so not as wet as lastnight

 

[Tile life]

Usually white in darker grout is salts that have risen up. Try a bit of white wine vinegar and scrubbing brush

 

[Jamie Cassey]

How did it turn out? Did you try the white wine vinegar and if you did, did it work?