Chris Fastie has already covered this in great detail, and contributor geobduffy has delved even deeper but I wanted to post a quick video on how to actually set up custom white balance on your camera, with a blue background, for optimal Infragram photography. Here's a quick video walking through the process on a Canon camera:
Update: I found a wiki page Chris posted with this process described as well: http://publiclab.org/wiki/infrablue-white-balance
Quickly, for those of you who don't like videos:
- Turn on the camera, and set it to Program mode:
- Now press Function/Set and down once to get to the White Balance menu, which probably has Auto (AWB) selected. Press the right arrow button to get over to Custom, where it will say "Evaluate White Bal.".
- Point at a deep blue surface, the kind of blue in RGB (or red, if you're using a red filter). The Infragram kits have shipped with a square of appropriately colored paper. At the bottom of this post is a square of "pure" blue, though I'm not sure if it'll work to point it at the screen. Press MENU to "set" the white balance. Press Function/Set to begin taking photographs. The camera will have to be in Program mode to use your custom white balance, and In the future, you'll want to redo this each time you take photos.
Your photos should now have a slight orangish tinge, like this image which Chris posted (or see below in the comments for a better example posted by Chris):
Update Here are red and blue squares, which may work (they're pure R and B from your computer screen) but I believe it's best to use a very clear pure red or blue material (paper) in the same sunlight as your actual photos, just before you start taking photos.
Note: If you use a red filter, you'll now need a red region to white balance: