Tile grout cracking "against Marble" -- Cures?

Oh, if you look at the pictures, if you "double click" on them, they
come up larger, making them easier to see....Tim

Dig it out and put in white caulk.

Yeah, flexible caulking is sort of where my "clueless" brain is
leading me....

Does everyone else agree?

If so:

1) What type of caulking -- acrylic -- ?? (tons of different caulking
at the store all made from different stuff).

2) Any tips on digging out the existing grout....I'm thinking there
must be something that might make it a bit easier.

tim birr wrote the following:

Caulk made for bathroom shower and tub enclosures.



You may not have to dig it out at all. Just caulk over it.

--

Bill
In Hamptonburgh, NY
In the original Orange County. Est. 1683
To email, remove the double zeroes after @

OP, again....

Thanks, guys.  I'm starting to "picture" all this.

My only issue with silicone caulk would be that I used it years ago in
another house, along a bathtub glass/chrome door, if I remember
correctly.  Needed to remove it a few years later and the silicone was
just about impossible to remove -- OK it was impossible.

While I don't plan on removing this, you never know.  Would the
polyurethane have good flex, as well as be somewhat "removable" in the
future?

Any change in wall or floor plane will experience movement and should
be caulked.  Any change in adjoining types of material will experience
movement and should be caulked (with the exception of 'like' materials
- stone to tile, brick to tile, etc).

Remove the old grout, clean the joints as well as you can, final wipe
down with alcohol to remove any soap or grease residue.  In general
you should not fill deep joints entirely with caulk if it is a
critical joint.  As yours are not, it's probably not an issue.  Use a
good quality silicone or polyurethane caulk meant for bathrooms (has
mildewcide in the mix), and in the color of your choice.

For critical joints deep joints should be partially filled with some
type of backer so that the caulk is thinner in depth than in width so
that the caulk will stretch more in the direction you want it to
stretch, and not pull away from the critical attachment points.
Again, not really an issue for your situation.

R

*The joints where you have cracks all seem to be narrower than the joints
between tiles.  Usually in small joints an unsanded grout is used.  I
suspect that the regular grout was used on the whole shower.  I couldn't say
for sure, but I think that you should clean out the old cracked grout in
those small joints and regrout with an unsanded grout.

Of course you could caulk, but you may not like the way it looks.

Grout is the wrong choice when one surface (wall or floor) joins
another.  Flexible caulk is the right thing to use.  There is enough
normal expansion/contraction to produce enough movement to crack grout.
I would dig out the loose grout, clean the surfaces at the joints of
grout, dust, soap, etc., and caulk them.