Turns out that Alex is quite a dribbler. Rather than try and constantly wipe his chin to keep his clothes dry I thought I'd make a bandana bib to see if that works better.
I found this pattern on Mad Quilter's blog which was great. I shortened it a little bit but afterwards realised that the pattern length would be fine.
I used toweling for the back and flannelette for the front. It works quite well so may have to make another.