I have recently just fabricated a bunch of 1 1/4" thick solid walnut table tops.  The planks I used were 5" to 6" wide and were glued together (using Titebond 2).  We cut the blanks to size and then ran them through the surface sander.  We took them to the finish shop and put a coat of stain on them.  After we let the stain dry over the weekend, we came in today and noticed that many of them have separated at the joints.  The separation travels in about 2 to 3 inches and is as wide as an 1/8" in some spots.  Any thoughts as to what would cause this?  Is my finish shop to dry?  Why did it only travel in a a couple inches?  What can I do in the future to prevent this?  What can be done with to save the tables that were close to done?

jjdjr1    First of all, the 5-6" wide is a little wide for walnut, to be gluing up.  My first question is, is it kiln dried lumber and if so, was it taken down to 6-1/2% moisture content? But if it was moisture.. you would be asking about warpage.

If is was KD, you should be fine with that. 
Next... when you dry fitted the wood before glue up, were the joints so good, it looked like a solid board. If you had to tighten clamps, even just a little, to pull the joint together, this is your problem.  Walnut is actually a pretty stable wood.

My guess is this based on my 30+ years of woodworking. You did not have straight tight joints from the start. Glueup was made with the comment.. "yeah that will pull up". 

Did you run each edge through the jointer before glue-up? Did you alternate the grain, up/down?

Let me know about the dry fit...and the size of your panels,  and I can get you to the next easy step...

KC

I agree with Kelsey, the width was my first red flag. As he said alternating the grain (up and down) is critical. We handle Craft Art Wood tops, theirs are almost always in the range of 3" wide. When you ran then through the sander, did you make sure to remove all sanding dust, to allow the adhesive to grab?

KC, isn't walnut a particularly oily wood? Would that make a difference?

water borne stain?

David, yep...  and Tom no... walnut works great.

Reading what wags wrote, I noticed I mis-read the post. Blanks were run through the sander.  I have never been able to run anyhting through my wide-belt to where I would get a glue-edge flatness.

Pictures would be great. I have glued up 10's of thousands of panels, and I never had a joint fail that I was aware of. It should be the strongest point after glue-up.

I do not work with wood much, but would biscuits help ?

jjdrj, Is your finish shop & your shop in the same building or different location?
What part of the country are you in?
How was the stain applied and what type of stain was used?
Stain Walnut????
To much clamp pressure?
We have fabricated many BB tops and are working on both a Walnut &  Cherry tops currently. What I have found is in my part of the country the Northeast during the winter months the humidity is very low and people are also heating there homes, this has a tendancy to dry the wood more and can cause the joints to split if the wood has not been finished and is unstable. We dont let any unfinished layup sit for more then a day in these very dry conditions.
Titebond II is a very strong glue and I have also used it for the same applications you have and what I have found is that sometimes the boards may split before the joints do. Has this happened to every table or just to one? Also is the spliting occuring on every joint?

Made the same mistake some 33 years ago on a 8' top. 5" wide Walnut is OK if it is fabricated correctly. My first flag was doing the edges on a surface sander and not a Jointer. Second The boards MUST fit perfect with out any clamp presser, if you have to clamp the strips to pull them together they will separate. The mistake I made years ago was thinking that an 1/8" space in some of the joints that could be pulled together with clamps would be ok not the case. The fix was to cut the tops apart at the joints run them through a Jointer and redo. With light clamping presser you should not be able to slip a sheet of paper in any of the joints.

Nice looking tops Steve. Is the cove wood countertops taking off for you?

Andy,
Most of the wood BB tops we do people like the idea of the cove for all the same reasons that SS customers do.I like doing them and the cove is a nice upsell. It,s strange they kinda go in spurts. We've had a few jobs recently for butcher block but also alot of interest in laminates.

i agree with all the only thing i would add is sometimes letting the wood acclimate to the environment it is going to be in helps as well