New hollow core door - was probably exposed to some water during storage prior to installation. No visible water damage or marks. Lay a long straighedge on and about an 3/8" of bow is right in the center. It's going into a pocket door frame so has to be pretty true.
Suggestions on how to un-bow it? I have thought about laying it across a couple saw horses bow side up with some weight on it and leave it in the sun for a couple days.
Your on the right tract IMO, But it is going into a pocket which as you stated has to be true. Personally I would just go buy another hollow core door if the bow doesn't remedy itself with the weight sun cure idea. I can get them pretty cheap from a resale auction. Now I do not know if you have this type of resource at your disposal but, Good Luck.
Yup, that thing would go in the dumpster. Hollow core doors are pretty inexpensive so I'd opt for a new perfectly straight one, especially since it is a pocket door. If it got wet enough to warp I'd have concerns that the adhesives could fail or are in the process of failing from moisture exposure.