I have just rooted a Ronde de Bordeaux cutting stored 1 year ago, in Feb 2008.
I rarely lose a cutting in the first 6 months and it is not unusual 1 year old cuttings in excellent conditions.
It is a very frequent mistake to add humidity to store cuttings, why??? the cuttings don't need more humidity they already have. To add a wet source is to give a gift for fungus and mold, cuttings don't need it!
You only have to wrap with an sterile and airtight plastic film. When you store it in the fridge, the air around the cuttings decreases the temperature and reach to or near 100 % humidity. When the air is saturated doesn't absorb more water, so the humidity of cuttings keep constant, that is the objective!
The method that works best for me is the following (I have used it for years). I learned this method from Leon:
1) Clean off dead wood, dirt, old leaves, branches, etc. from the cuttings.
2) Make a 10% bleach solution (9 parts water + 1 part bleach).
3) Dip the cuttings in the bleach solution but don't soak them for a long
time (30 seconds is enough).
4) Take them out of the bleach and let air dry on papertowel.
5) Do not rinse them under water after taking them out of the bleach
solution (the crystals of bleach that dry on the cuttings will deter
fungus and disease).
6) once they are dried, wrap the cuttings tightly with the stretch plastic wrap you use in the
kitchen.
7) Make sure that your cuttings are labeled.
8) Place your cuttings in a plastic bag and seal.
9) Place in refrigerator.(never freeze the cuttings).
I use to graft buds from stored cuttings in late spring and summer, on account of this I need a reliable method of storing, the buds need to be in perfect conditions for grafting.