Applying first filler coat to wing

With factory built wings the foam cores are extremely accurate and no micro/epoxy mix needs to be added to the wing surface except in the spar area and underside of the trailing edge.

After a thorough sanding (with 1m block!) the rest of the wing surface can be filled with MS filler. I added 30% micro (by mass) to this and applied it with a short bristle roller.

Factory wings have had the outer glass layer sealed by rubbing dry micro into the outermost layer while it was still curing. If your wings did not have this treatment they may still be porous. If you add MS to a wing like this the solvents might attack the foam underneath -BE CAREFUL!

Try and get a second cross coat of MS on before the first is fully cured. If you let the first cure you need to sand the whole wing to ensure the second coat attaches properly.