We just received a painting on rice paper, acrylic I think. The customer was rather difficult. She insisted that it should not only lay perfectly flat, but that all the small crinkles in it would be smoothed out. She said that she had other pieces framed that were perfectly flat. Couldn't we just iron it??? 
We said that a mat would help a lot in flattening it, but because the paint has been applied, a slight buckling has happened to the paper and probably will not flatten out completely with a mat.
We also mentioned that we would refuse to dry mount it, and suspected that her other pieces may have been done this way. She said no they were not.
You can imagine that now she is looking at us like we are idiots. So we defer to you. Do you all have any suggestions, comments or ideas about:
1. how her other pieces may have been handled?
2. how to flatten this piece without dry mounting it?

We said that a mat would help a lot in flattening it, but because the paint has been applied, a slight buckling has happened to the paper and probably will not flatten out completely with a mat.
We also mentioned that we would refuse to dry mount it, and suspected that her other pieces may have been done this way. She said no they were not.
You can imagine that now she is looking at us like we are idiots. So we defer to you. Do you all have any suggestions, comments or ideas about:
1. how her other pieces may have been handled?
2. how to flatten this piece without dry mounting it?