Thnaks for the information.

As I want to bring some flour home with me I just thought I'd check out your advice. First, I buy flour and put it in small plastic bags, so it doesn't explode everywhere. Then I rub some cake flour over my face (to check I have the right one) and then I go through customs. I'm sure it will be fine.

I am a little worried by US Customs. I travelled back though the Canadian border once. There was a big sign telling people not to make any jokes. Then they started askign me lots of questions about fruit - very strange. I had to eat the apple I was carrying before I was allowed in. Are Canadian apples all that bad? Oh well I suppose it only takes one bad apple.