I, for one would be interested to 'see' this method in picture form.....Should be interesting, Chris.
As I said in my last post I am using a flat iron to straighten my SMALL bird quills, which entails covering the curved section and gently running the iron over the (covered with a cloth) bent section and (again very gently) lifting the end of the float.
After waiting for the (warm NOT hot) bird quill to cool it is somewhat straighter, but a couple of goes gets it as straight as it is ever going to be! (or that is necessary).
I am talking bird quills here, such as crow, pigeon, pheasant and the like...
Large quills, such as those from a Swan/Canada Goose etc. are extremely difficult to straighten (IMHO) as they are, by definition partly roundish (at the top end) running into square/rectanglar (in section) as it runs the thin, bottom end AND BECAUSE OF THE VERY HARD, ALMOST PLASTIC LIKE material ALONG ONE SIDE (KNOWN AS THE SHAFT OR RATCHIS) which runs from where the round section ends down to the tip of the feather, it does not bend easily.
As I said in my last post, when you try to straighten AGAINST this hard side (which is the same on all LARGE quills) it is impossible not to cause a bulge (where it straightens) and an indentation in that same hard side, or ratchis.
This my take on it, and is NOT to say the method outlined by Chris above, will not work, as I obviously haven't tried his method. We all live and learn, as they say!!
NB! Regardless of all of this, any quill with its natural curve can be used as a float as it is, and I have many floats in this format. I just like to try and get them as straight as possible ,cos I'm a fussy bu**er!!