Poly has sunk where the wood strips meet

Q: I just had new hardwood floors installed (Brazilian Cherry and Red Oak). After applying the second coat of poly, the poly has sunk where the wood strips meet. This sinking is pervasive across both the first and second floors, and across both wood species.

Looking at the wood, for the most part the installation is tight with few gaps. Can you advise as to why this is occurring and what is the best remedy?

A: I’ve actually never had to sand and finish a Jatoba floor. I have heard that it can be safer to finish with a water borne, because the occasional batch will react with solvents in oil based products and turn white. I’m not really sure what is happening in your case. Has there been any crowning of the wood? Has it been sanded flat?

Follow-up Q: Thanks for the prompt reply. I am not sure what you mean by crowning, but the wood has been sanded and appears to be flat to the eye and when rubbing your hand along it, prior to the laying of poly. Also, the issue has occurred on both the Red oak and the Brazilian Cherry, which have been laid on two different floors in the house. The problem is also wide spread and occurring over at least 20% of all the seams/joins. I’ve tried to find information online about this type of result and have come up empty handed.

A: I am not sure what is happening here. I would suggest the person coating the floor to switch to a different finish. Buff the finish well and when applying another coat, apply cross grain, and then go over the area with the grain.