In our 40 year old bathroom, grout was used where the horizontal plane met the vertical and it was cracking horribly so I dug it all out and caulked with the same sanded product you are considering. I wanted the texture to look similar to the rest of the bathroom. I regretted using the sanded because it seems to attract the dust and dirt and really "hold" on to it. In another bath, I used a non-sanded version and that is much better for cleaning. I will be digging the sanded stuff out and recaulking again but with a non-sanded version.

I have also attempted to use a 100% silicon caulk and say attempted because boy is that a bear to work with. You gotta be quick and get it right the first time. No playing around because in less than a minute it starts tacking up. Sure the pros use it but they know what they are doing. For an average homeowner, I say stick with a silicon blend or a long-lasting acrylic. Also they are much easier to remove down the road as silicon must be mechanically removed most of the time and that is not fun.

Thanks Aurora. Dirt and cleaning is definitely a big consideration. What you said is making me lean towards non-sanded (and definitely away from silicone as an option at all).

Naveen, could you have had the countertop installers put in the silicon grout for you in a color that matches your current backsplash grout? That way you get the added protection of the silicon and a better caulk job. If you are doing it, I would still use a colored caulk but just non-sanded.

No, unfortunately they just had a white caulk, and they said they could put that, but suggested I get a colored caulk to match and do it myself.

Tape where you want the caulk to go, wet your finger to smooth, don't put too much on, and consider an electric caulk gin from Home Depot (Ryobi) - it will lay down a consistent bead online any manual caulk gun! Put down a small bead, wet / press, lift tape, let set.

Thanks everyone. One problem, and why I'm undecided between sanded vs unsanded, is because the gap is uneven. It is about 1/4" wide at one side, but eventually narrows to a much tighter seam. (I can't replace the backsplash for the time being, so have to live with this for now.)

I realize that for close gaps, you use unsanded, but for larger gaps you should use sanded. I have both. Is unsanded a no-go on those big gaps, and if so, then is sanded ok in the small gaps?

Refer to the Brand MFG installation instructions they will state their joint specifications. That will be undebateable advice.

Got it. Thank you!

I have learned something here. I did not know that the sanded caulk should be used for larger gaps and non-sanded for smaller. Any reason why?

Second, a bad tile job was also done in a relative's kitchen. The tile guy grouted rather than caulked where the quartz countertop meets the backsplash. She refuses to have him back in her home. She asked me to help remove it with my dremel oscillating tool. I am reluctant to do so until it starts failing. Any hints on removal?

Aurora - I believe the reasons are that sanded won't shrink b/c of the sand, which makes it better for large gaps. The downside is that it's harder getting it into tight gaps — at least, that is what I've read. (Will find out for real very soon!)

We had some problem spots like that, and I filled them with skinny "backer rod" (it's a flexible foam cylinder to stuff into cracks), sealed it in with clear silicon and then topped it off with the colored caulk that matched the tiles.

Truly a PITA, and I could have skipped the silicon, but that backing rod is wonderful.

I thought about that, but although the gap is a little wide, it's not that deep. Maybe if I cut it and just squeeze it in it could still work. It does feel like it needs some support there...

100% silicone works great. Our tiler filled that junction with grout and it cracked after 2 weeks. I removed it and put beige silicone. It is easy to smooth out if you spray aerosol window cleaner immediately after application before you run your finger on it. Silicone makes for a great water seal. Backer rod is also what I would do for the larger gaps.

https://www.youtube.com/watch?v=nHwmqkoz1tE

Silicone will often let a much smaller joint.

You can get tinted silicones. I got some that matched our counters pretty darned close in the previous house.

Taping for caulk is a waste of time. Lay a bead, spritz it with Windex, run a wetted finger down, wipe off the Windex overspray. Perfect and fast.

I read a tip recently to use an ice cube to smooth caulk- would lubricate like the windex. Seems a worthwhile test item.