For educated help, post pics of the granite, please.

I am a fabricator. Cracked sink rails can occur for no reason at all. After the stone survives the processing in the shop and the handling to get it installed without cracking the obligation of the fabricator to replace it ends. Do you know if the crack was present immediately after install? If not its your problem although most fabricators will try to work it out with you.. If yes then a remake or some other arrangement to satisfy you is warranted. (Usually the fabricator polishes out the crack and gives a discount in lieu of a replacement.) If the sink rail was "rodded" then a proper repair will make the crack near invisible with no risk of opening up. Rodding is the process of cutting a slot in the underside of the sink rail and glueing in a rod. Functionally it is much like rebar in concrete.

"Cracked sink rails can occur for no reason at all."

No. Properly installed natural stone doesn't just spontaneously crack. There is always a reason, and it's usually fabricator/installer/designer error. And customer abuse.

While Sharon doesn't specify the length and location of her crack, I'm betting it's from the front edge to the sink cutout at a corner because a reinforcement rod failure would be parallel to the sink and unlikely to show up so soon. In either case, the best solution is an apron front sink retrofit.

"No." actually, yes. of course there is a reason but it can be for reasons not apparent to the end user. Stone, and even engineered stone, can have residual stresses in it that can crack a rail while a piece with a sink cutout is sitting alone on a work station overnight. Don't ask me how I know. It can also happen while the part is on the machine getting the sink cutout. Normally, but not always, this type of failure would occur before or during install given the material stresses imposed by fabrication and installation.

With that said a sink crack which occurs after a proper installation is usually because someone stepped or sat on the rail as the cabinet structure under the rail is often less than rigid. It seems there is always a light over the sink and a person installing the lite bulb will use the countertop sink rail as a convenient support.

There is no rod reinforcement. It is located in the narrow piece in front of the sink, but not at the corner. It was not discovered immediately but about a week after install, before we moved in. It is well hidden yet It goes all the way through to the underside and all the way across, top and bottom.

It looks natural, although the light reflection doesn't look good as if someone tried and failed to buff it.

They did try to put resin in the crack and buff it. There is now a dimple in the surface where they didn't do a good job of blending. The owner has been out and wants to send the same guy to try to repair it...again. I guess it's his attempt to appease me since I mentioned replacing it instead.

@Granite City Services Out of curiosity is there one or more types or grains of Granite more likely to have this happen for an unknown reason than others? To me it looks like the crack was between the two colors in a lighter color and see other natural fissure cracks in the slab. Could this crack could of been a fissure that cracked?

Yes it is right where the color changes. It may have started as a fissure and then cracked through in transport or install.

Now that I am learning more, should the fabricator have put in reinforcement rods in front of the sink before transporting this piece and installing it? I am not an expert on this but am learning a lot more now that I am dealing with it.

Sharon:

Rodding is old school granite fabrication and is obsolete with the invention of modern tools like the Sink Hole Saver. Improper rodding and sink installation has caused a world of trouble in the natural stone industry.

"Could this crack could of been a fissure that cracked?" maybe, but usually only because the install was deficient such that the piece of stone was under some stress. Properly installed there would be no stress on the stone piece. re: rodding being obsolete; when I 1st started in the industry over 20 years ago there was a lot of differing opinions on the value of rodding. I had a study conducted under the direction of the Professor of Material Science at a local University. The results of the study clearly indicated that rodding substantially reduced the potential for cracking of the rail. It also relieved any residual stress in the material which a "Sink Hole Saver" does not do. The idea of a sink hole saver has been around for a long time; before it was a commercial product it was a stout piece of angle iron clamped along the edge where the sink rail is. Not really a new idea. Joe is right that rodding can cause failures if done improperly; a steel rod can rust and split the stone. This is called rust jacking and can often be seen in older concrete structures where concrete has crumbled exposing the rebar. Same thing happens in a countertop of a steel rod is embedded in the stone in a way that allows moisture to get to the rod.

Two more photos. I'm afraid this will deteriorate with time.

Granite City Services:

Of course rodding increases the strength of the stone at the rail by about 600%, however, that is practically meaningless as that strength is only useful from the shop bench to the kitchen cabinets.

When stone is properly installed on flat and level cabinets, the cabinets provide all the strength in tension that natural stone doesn't possess to keep it from failing.

A properly strapped sink turns into a 9" deep stainless steel sink into a truss, much stronger than any rod and a blessing if repairs ever have to be made. And strapped sinks don't leak or suffer black/brown mold/crud. Old school rodding in combination with leaky sink clips and Sink Setters have created some of the most trouble plaguing the natural stone industry. It is poor unnecessary practice, with few exceptions.

I'll be happy to take your professor on a few sink replacement jobs so he can get the context he's lacking in his study.

Sharon:

The light reflection in your first picture should look like this:

Nice 'n crisp, not that blurry blob you're showing.

Sorry

At my age you're lucky you got a picture at all. Technology isn't my thing. I have better things to do with my time than to play with a phone or a computer. I did the best I could. I was looking for an opinion not criticism.

I had a sink rail crack, when a painter stood on it to paint above my kitchen sink. It was a fissure that was probably destined to become a crack sooner or later.

It's been filled with super glue for years, zero issues. (Thanks for the idea Joe! :) )

I'm not expert, just an idiot home owner. However once that is polished I don't think you should worry about it any further. I doubt a resined repair is going to further deteriorate, and there is no way I'd risk damage to my cabinets having that slab removed.

I could be wrong but isn't the filler acrylic or epoxy color matched? So I would also think it takes a little artistic ability to match colors to make the crack nearly invisible, but I don't see a color match in the your crack. At least two colors should of been use and looks like only clear was used.

Yeah, I question whether it is smart to have the same guy come a second time to try again to repair it. He might do more damage than good.