never heard of using an iron...nor have I ever heard of veneer edges at the seams curling or lifting as you describe. sounds like the paint caused the veneer to come loose ....or they were loose to begin with and you just made it more noticeable by apply the coat of paint. I might consider going back to where you purchased them and telling them what happened to see what remedy they might suggest,,,they may choose to replace defective furniture or suggest a way to fix this for you .....good luck .. LJ