You need to let the shower dry for several days (no use), at least 72 hours until the color of the grout becomes consistent. You then need to seal the grout so that it does not absorb water and change color. Use a higher end grout sealer that will last longer. Two coats may be needed if water does not bead up on the grout after the first application.

 

I already sealed it two months ago after the grout was replaced. However from what I read I thought that the purpose of grout sealer is not to create a water proof barrier but rather to prevent staining. I used the 511 Impregnator Sealer.

A couple of other questions...if the mud pan is wet underneath won't it take much longer than 72 hours to dry? Is the mud pan (in which the tiles were set in thinset) supposed to get wet?

 

Should be deck mud that the pan sits on and is overlayed with to create the bed that the tile is attached to.


Higher end grout sealers will bead water when you try to wet them after sealing. The fact that the grout is changing color, to me, it that they are not properly sealed. Try a different sealer, One that has "Gold" in the name. More expensive, but I have had great results. Found at your local Big Orange box store.

 

I'm not a professional, but from my understanding - it's not expected that the grout sealer will form a completely protective waterproof barrier. As such - some water will get under it, and it will soak into the mud pan. The idea is that the waterproof barrier is below the mud pan, and that's what prevents water from leaking to the floor below, and the walls. Then the drain has weep holes on the side, such that any water that gets into the mud pan eventually finds its way towards the center drain, goes through the weep holes, and out.

I believe this water that's literally soaked into the concrete then can also keep your grout from drying up.

As such - the question is - how long should it take for this water that's "in the pan" to dry up? Is it hours? Days? Weeks (essentially never, such that it stays wet all the time)? The answer to that - I don't know.

I'm having a similar issue, except worse than yours I think. I'm starting up a new thread to ask about it, and will post a link here.

 

I'm not a professional, but from my understanding - it's not expected that the grout sealer will form a completely protective waterproof barrier. As such - some water will get under it, and it will soak into the mud pan. The idea is that the waterproof barrier is below the mud pan, and that's what prevents water from leaking to the floor below, and the walls. Then the drain has weep holes on the side, such that any water that gets into the mud pan eventually finds its way towards the center drain, goes through the weep holes, and out.

I believe this water that's literally soaked into the concrete then can also keep your grout from drying up.

That's all correct. I'll take a look at the other thread.

 

Here's the thread with my issue - a more extreme example of the problem you might be having:

https://www.diychatroom.com/f84/mud-shower-pan-bad-634415/

 

Did you ever work it out.

 

Yep - see the other thread; I posted update/pic in 2021. Been using the shower for 5+ years now and it's been good.

It's been good, though I did have one issue, where I made the mistake of using pre-mixed thinset. Never again. As a result of that a portion of my threshold went a whole year and had not actually set (dried), and kept expanding; I took it out and redid it using the right stuff, and it's been fine since.

 

(FWIW - though I wasn't referring to grout - I've used the Mapei grout - did not like it at all. It was very weak. LIke I could literally scrape it out of the joints with my finger days after installing it, even though I mixed it to specs. I've noticed that Lowes stopped carrying it - I figured it was for that reason - it's just not good.)

 

Either way, Lowe's hasn't stopped carrying it (at least not in general). If something was wrong, it wasn't the brand of grout per se, it was something else. Mapei grout is fine, both premixed and standard.

As for premixed thinset in a shower, yes especially when waterproofing it's possible that stuff will virtually never dry. Other than mastic for wall tile or something like that, premixed "thinset" is never a good idea.