Chuck brings up a potential issue. Traditionally, built up heels were used on classicals without dovetail joints, and dovetails used on guitars without built up heels. I haven't seen any delaminating on the couple of multipiece necks (longitudinal laminations) that I have steamed out that I built with original Titebond as the glue. Fish glue would probably be the most prone to separating from steaming. If you want to be safe, use urea-formaldehyde or resorcinol, which are pretty impervious to moisture and would take a lot more heat to separate than you use when steaming the joint.
_________________
Howard Klepper
http://www.klepperguitars.comWhen all else fails, clean the shop.