I have never had to alodine such large sections before so decided to build a couple of long troughs (one for alodine, one for rinse water) from guttering that are big enough to hold the rear spars. Went a bit over the top and fitted them with taps to allow easy draiining - however, I wil no doubt use them again as I progress through the build.
troughs for rear spar - with an earlier and smaller unit.
