For all electronics, I don't use rice OR silica gel - they will only pull moisture out of the surrounding
air hoses until about 10-15% humidity remains. I prefer to use
1.5-3.0A molecular sieve with the item in a tight mylar pouch and heated to about 105F (or the max the item will take safely). It will pull down to almost 2%. Used mostly by chemists to desiccate fluids (pulling water out of petroleum in a column), but decently cheap. This is the place to by it from:
http://www.sorbentsystems.com/ . I use their siilca gel boxes in my camera cases, but for any electronics I'm repairing that has been water exposed, sieve is the way to go.
Even on my 1Ds3, the "sealing" is nothing more than foam rubber strips and mylar adhesive tape at the joints. I had the camera sent to Canon CPS ages ago and they did a shutter replacement. However, when I pulled the camera apart recently, the "seal" tape was torn at the seams between the cover and body, but never replaced when they serviced it. So, I laid the ripped pieces onto a sheet of 3M 200MP, traced it out and replaced all the pieces around the camera. Then, cut new (denser) foam rubber strips and filled in all the gaps. Now, it's much more water-resistant than before.
Moral of the story is that even if it's been back to CPS, don't trust that they'll fully make it water-resistant if not necessary! I've hosed mine down with a garden hose with a 70-200/2.8L II on with no problems (and of course, a nice tight Heliopan filter on the front, even though not needed). Just remember that seals DO shrink and DO get old/brittle/crumbly over time. It is a combination of the film tape, foam rubber strips, AND rubber grips (on the outside) that make the combo more water"proof". The rubber pieces tuck down into grooves and some of the joints are between pieces. With enough water and/or pressure, water will still penetrate the joint.
NOTE ABOUT THE HOTSHOE: at least on the 1Ds3 - the area where the shoe is mounted is screwed down tight and "sealed" with some caulk/glue. As is the area around the lens mount. The DoF preview button is also sealed with this glue. There is no need to add any additional sealing on the 1 series. However, I have a small rubber hotshoe level that slides in - it keeps the top from getting scratched, gives me a simple level, and keeps water out of the left/right rail should it get dampened.
After seeing this, I wouldn't trust any of the lower cameras to any water - anybody who has a "survived it" story was just lucky and their body was probably pretty new.
In case somebody wants to see what the "sealing" looks like: go
here. The light grey tape pieces are the Canon original seal (the tears are directly along the case seams!) and the dark tape is the 200MP that I was tracing/creating with.
