The nitrocellulose that is being referred to is nitrocellulose
lacquer.  This has been used to finish the finest pianos for years.
Yes, it is highly flammable and must be used correctly.  It is
currently available and is a wonderful product if used correctly.
This is not flash paper or flash cotton.  Even movie film was
nitrocellulose-based and would spontaneously combust, hence the
invention of "safety film."

Why Talcum powder?  Sealing pouches with egg white and thinned down
rubber cement was mentioned.  Once applied and dry, it is important
to rub the mixture with talcum powder.  You do this because even
when dry, rubber cement will stick to itself.

Interesting note: I have used zephyr skin as a veneer in restoring
Art Nouveau antique furniture.  Many pieces had this skin as a
decorative surface and it was in turn finished with nitrocellulose
lacquer.  Everything was then hand rubbed to a brilliant luster.

Bob Yorburg
http://www.bobyorburg.com/