my grout's gone yellow!

[liverplum]

I did a little favour for someone and raked out some cracked grout for them and quickly re-filled with some of the unibond pre mixed stuff that was kicking around. They didn't use for 48 hours but a week later they have noticed the grout is turning yellow!

Any ideas why?

I am going to go back and remove and re do and replace with something else but wondered if it was an underlying problem?

Any thoughts welcome.

 

[Gazzer]

Cheap Grout and maybe contamination from previous grout.

 

[brinkley]

was the water clean that you washed off with?

 

[brinkley]

did you completely remove the grout from the joints ?

 

[liverplum]

to be honest I probably did not completely remove the existing grout but just cleaned out the lines where it had cracked and re filled. I take it the job requires complete removal of existing grout and re application? Will the whole shower cubicle need to be re-done?

 

[Alan.P]

A few possibilities, contamination from the substrate and or other materials, dirty water used for mixing and or cleaning, cheap grout, and maybe something other than these.

Hard to say for certain, a few more details needed.

 

[Alan.P]

to be honest I probably did not completely remove the existing grout but just cleaned out the lines where it had cracked and re filled. I take it the job requires complete removal of existing grout and re application? Will the whole shower cubicle need to be re-done?

You posted this as I was typing lol, obviously if the old grout was discoloured this could be the cause of the new grout discolouring, you will need to remove all of the old grout yes. How much of the shower is affected ? it will probably be best to redo the lot but what has caused it in the first place ??

 

[kilty55]

have they been cleaning the grout/tiles with bleach

 

[Gazzer]

Why not try a grout colourant from Mapei or Aquamix ?

 

[liverplum]

I've never used a grout colourant....

Quite why the grout had cracked int he first place I am not sure. It was done originally around 6 months ago and I guess maybe because the grout was already going off when applied or not mixed correctly or cheap ready mixed stuff maybe?