I was never told exactly how to gradually intensify a note (and vice versa). Naturally I adapted to using 'hard' pressure. Tense force from my shoulders were transferred into pressure from bow to string. It felt great when the sound became louder and I felt totally in control.
After a period of studying in London, I'm slowly realising other ways of doing a simple crescendo without potentially injuring myself (due to constantly creating unnecessary tension).
All you need to do is relax, place the bow on the string (and just that! Be conscience you're not 'preparing' such a simple movement - you might realise you're doing all sorts of shoulder lifts / head stretches / heel lifts / etc. which is totally unnecessary - unless you can prove otherwise), choose a slow speed to start the bow off with, then gently increase the speed of the bow - not pressure.
So far I've found it miles easier than all the 'moving to prepare making an increase of loudness' / 'serious forceful powerful flair' - you know what I mean. (Right?) My sound has become much more resonant and it's a lot easier to make a louder sound too!
Anyway, of course I don't believe you should cut out all pressure altogether, but (as with all areas of violin playing) learn how to use the element and not just have it come out because of old habit - make use of it to create a colourful and vibrant palette!