Hrmph
You shouldn't even be using tippex.
If you manage to make a mistake then simply draw a line through it to make it invalid. Using tippex to cover your mistake is not a desired method in many schools. I'm seriously doubting if even Air lines would accept looking at them in that format.
Point of interest, it makes your logbook look a lot nicer if you use ONE type of colour in it instead of mixing it up with black and blue. Learning to write in small letters makes it a lot nicer and can be done by buying one of those pens with a very very fine point.