I hate to think about summer leaving and fall arriving but I love winter also so I am always in a win win situation unless the temperature rises above my comfort level of 80.
But anyway. I love preserving the gorgeous fall leaves to use in my art be it painting, or some other "form".
Here is how I preserve the leaves so that they remain colorful, soft and supple.
1 part glycerine / 2 parts water. Place the mixture in a flat pan and totally submerge the leaves in a single layer in the liquid. You will need to "weight down" the leaves to keep them submerged. This year I am going to try some screen to see how that works rather than something heavy. If you use a heavy item
I would suggest after a couple of days to turn your leaf over then weight again for the remainder of the time. This way both sides of the leaf will get "treatment". I remove mine in about 4 days but no longer than 6. If at 6 days they are not supple enough I would suggest increasing your glycerine to equal parts. . If they soak too long they will absorb too much of the glycerine and weep. Depending on where you live you may find temperature etc. plays a part in the soaking time so you may need to experiment with "time" as well as "solution strength".
After they have soaked I gently press between 2 sheets of absorbant paper towel and put into a telephone book to press them flat... Make sure that they are straight, no edges folded under, etc. I only use one leaf per page and about 15 pages between leaves and leave mine for about a day or so .. or until I want to "use" them. However; you can paint on them immediately if you so desired.
Glycerine can be purchased in the "drug store section" of most stores like Wal Mart, Target, etc. and is relatively inexpensive.
Hope yours turn out as beautiful as mine have in past years.