The request for this weathering exercise was for a faded Loco – not necessarily filthy but ‘aged’ as opposed to heavy weathering.
Loco’s used in Washer Plants were particularly vulnerable to age fade and fade by harsh chemicals used in carriage cleaning. This also stopped the build up of grease and grime.
I have done partial fades before in OO but never in O and never 80% fade. After some (a lot) thought I decided I would not remove the original transfers and spray over the top of them. This way they would just be visible under the fade and I could position new transfers over the top.
I masked all windows, the black cab roof, which I would weather later, and both wasp striped ends.
I used Railmatch Faded BR Blue and it worked very well. My conventional weathering then followed over the whole Loco.