[whatsacubbard?]

I install a lot of laminate countertops, and any time I have a "field joint" I use a two part color matching epoxy. I'll have to get the name, but it comes in two tubes attached together and after the ends are cut, it squeezes out together. Mix with a puddy knife and while its still wet, it can be cleaned with a wet rag. I also use biscuits which really helps line up the two surfaces. Put a nice amount on both edges of the joint and use through bolts to clamp together. Wipe up excess with a wet rag. You can tweek the two surfaces with a rubber mallet. No need for seam fill when your done. By the way, this is far easier with two people. One under top wrenching bolts (usually in an awkward small cabinet) and one up top watching the seem.
Hope this helps.