I have been road-testing two types of freezer paper for use in stencilling: C. Jenkins and Reynolds branded papers. Both are US-manufactured products. The experiments I have conducted are a bit on the unscientific side and without controls, so I should preface all this by saying that its my opinion only! You may have a different experience, so any comments or corrections are quite welcome.
Reynolds freezer paper is sold by the roll and is 18" (about 46cm) wide. I'd estimate its weight to be about 70gsm (or around 45lb) and it has a very shiny plastic-coating on the reverse side. The C. Jenkins freezer paper is a little heavier at 54lb (about 80gsm) and is sold as flat pre-cut sheets of 8.5" x 11" (28cm x 22cm). The reverse side also has a plastic coating and is quite waxy.
The reverse side of C. Jenkins (left) and Reynolds (right) paper. The Reynolds paper is much shinier.
Being the lighter-weight of the two, the Reynolds paper is more transparent. This is certainly of advantage when you are tracing a design. I found that I really needed a light box (read: window!) to trace a design onto the C. Jenkins paper.
Freezer paper sitting over a printed sheet: C. Jenkins (left) and Reynolds (right)
Both papers were easy to handle when cutting. I tried out both a craft knife and small pair of scissors. There is a downside to the Reynolds paper though: being dispensed from a roll it has the tendency to roll or curl. You really neeed to take the time to flatten it out before you begin.
I found that the Reynolds paper fused more quickly to the cotton fabric that I tested it on (about 30 seconds). I'm guessing that this is due to it being a little thinner and more pliable than the C. Jenkins paper. I needed to iron the C. Jenkins paper a little longer. After fusing the papers there was, however, no discernible difference between them.
Fused papers on calico: C. Jenkins (left) and Reynolds (right)
When you are ironing your freezer paper, its important that you turn the steam-setting off on the iron. Steam prevents the paper fusing properly. I tried ironing both papers with a shot of steam, just for fun. The Reynolds paper was a bit more tolerant, with just a corner coming away. It is difficult to see from the photo below, but about half of the C. Jenkins paper didn't fuse.
C. Jenkins (left) and Reynolds (right). I will be making sure that I empty the water out of my iron before trying my next stencil!
Both papers worked very well for the stencilling. If, however, I had to pick one over the other I think it would be the C. Jenkins freezer paper. I liked the fact that it didn't curl, could be stored flat ... and well , I have always been a sucker for heavier-weight papers! Of course, if you were wanting to make a very large stencil, then a nice big roll of Reynolds paper would be just the ticket.
If you are in Australia and would like to buy freezer paper, please see this previous post which gives a few suggestions as to suppliers (take a peek at the comments too, as some really great suggestions that other people have left).