I'm more of a Premo gal, myself, but I do have some Fimo in my stock (mostly the translucent that's supposed to be prone to plaquing, for use in faux stone), and maybe someone who reads this will find the information helpful...
Fimo has officially changed its recommended baking/curing temperature-- lowered it from 265° F to 230° F! That's a pretty drastic change! Fimo has always suggested a slightly lower temperature than some other clays, but before, the difference was only 10° F. Now there's a whopping 45° F difference.
This new recommendation is showing up on the newest packages of Fimo. Apparently, the company is indicating that this is an energy-saving issue that they took into consideration when planning the formula for the new recipe of Fimo Soft, which hit the shelves last year.
However, the word is that even older packages of Fimo-- those that don't bear the "new and improved" labelling with the temp. change-- should also be cured at 230° F. (Well, I know they "can" be, but I'm not sure if they go so far as to say that you "should" use the lower temperature...) All types of Fimo brand clay can/should? be cured at the new temperature, including Fimo Classic and Puppen Fimo.
It's a bit confusing, somehow, and disorienting... One of the Great Truths of Polymer Clay-- that different brands can be "mixed and matched" at will-- has been shaken, if not collapsed. Because... if I mix some of my Fimo translucent with some of my Premo violet, for instance, I'll have to decide what temperature to cure it at. Before, I would've set it to 275° F and never thought twice. Now... I'm just not sure! Maybe 275° F is too high. Will it scorch the Fimo? Weaken it? But then what about the Premo component? Will it cure properly if it doesn't get the higher temps?
(...holds head in both hands, rocks back and forth, and mumbles incoherently...) ;o)
Ok, so I'm dramatizing things a bit. (g) It is one more thing to keep in mind.
If you want to read more about this, here's a link to Crafty Goat's blog post on the subject. She has a link to an e-mail conversation between Garie (a polymer clay teacher and artist) and the company that manufactures Fimo brands of clay.
You never know what mind-blowing event will take place next in the ever-evolving world of polymer clay! ;o)