As polished marble has very little chance of water absorbency there is a much less chance of staining and therefore sealing is not really necessary.
Is it necessary to seal marble tile.
While not all marbles are delicate most are highly absorbent and thus easy to stain and etch.
Unlike a ceramic or porcelain tile floor it s not just the grout lines where sealing is critical but the entire surface.
Marble sometimes gets circulary etches scrathed into its polished face with sanded grout.
Sealing prevents water absorption which can oxidize the iron deposits creating rust stains in the marble which are very hard and often impossible to remove.
Since it is carrara marble a white marble it can contain embedded iron deposits and you need to seal both the tile and the grout in the shower.
The process for sealing a marble floor is relatively easy and should take less than an hour with each application.
In addition if the marble is not absorbent then it will not absorb the sealer and the sealer wont work.
When should you seal marble shower tiles.
You can apply another coat of sealer on the tile too.
Shake a few drops of water on one of your tiles.
White marble including carrara and calcutta marbles often contain small deposits of iron.
Then wait 3 days minimum after grouting giving time for grout to cure and then seal the grout.
I would seal the tile before grouting.
The first instance is when you have put white marble in your shower.
Then grout using non sanded grout.
How to seal marble floors before grouting.
Tile made from marble travertine granite terra cotta or slate looks beautiful but is susceptible to spills stains and chipping if it is not sealed.
A major consideration when deciding whether or not to seal your marble shower is that hard water stains are a common theme in bathrooms specifically in showers and baths.
As polished marble has very little chance of water absorbency there is a much less chance of staining and therefore sealing is not really necessary.
Many manufacturers do not seal the tile ahead of time so try this simple test.
There are a few different circumstances that will require you to seal marble shower tiles.