Dude! Don't use the compressed air can! It is not safe for the image sensor! It is like your breath blowing. The compressed air can has moist inside that expels and damages the image sensor in a little at a time.
What nonsense, air has moisture in it. People use Canon cameras in 100% humidity environments (with condensation, even). There is more B.S. to the perpetuated advice given on this topic than any other I've seen in a long time.
Ok, well there is more than just moisture in a can of compressed air, but honestly the moisture content isn't the really the biggest concerns. The first of course is that even small dust particles propelled at high speeds are really bad for the sensor. Bad combination, bad idea. Second of course is that high pressure on the shutter blades is a terrible idea. Yes, they will probably (note the word probably) come back into shape at first as long as you don't use to long of a burst and keep the PSI at least somewhat under hurricane force by moving the can back a bit, but your stressing them in a way they were never designed to be stressed and honestly it's just a really terrible idea right there. Also keep in mind that the shutter blades are pretty small - which means that it really doesn't take a lot of air pressure for it to suddenly be a tremendous level of PSI of force (Pounds per square inch).
As another real world example, do you know why old vinyl records will usually have the popping and hissing sounds in them? The reason for that is that every time you play a record on a record player, the surface of the vinyl melts from the pressure of the needle and any dust particles or debris inside the groves of the record will actually melt into the surface. How can that be? Well your looking at the tracking weight of the needle being distributed onto the record with nothing but the tiny surface area of the needle to support that weight. When you work that out into pressure expressed as pounds per square inch, it's a pretty scary thing indeed.
Same thing happens when you hit those small, thin shutter blades with compressed air. To you it may not seem like much, but to those little blades it's more akin to hurricane force winds. It's just a really, really bad idea.
Then add in Boyle's law - see the thing about compressed air or any gas is that it expands you get a noticeable drop in temperature - which can be bad for your sensor but even worse for the shutter blades - again they were never designed to deal with that kind of stress. So yes, they'll probably hold up under that sort of abuse for a while, but eventully - well, eventually your looking at replacing your shutter long before you would normally have to because of all the abuse it's suffered.
This of course doesn't even mention the fact that you have to.. how was it you put it, "pre-spray" to get any buildup of gunk out of the way so your not saturating your shutter with that - and well I think you've come up with a cleaning procedure that will damage the shutter almost immediately if not done with tremendous care and even if done with tremendous care will probably shorten the life of the shutter considerably.
