Track weathering with acrylics

[Midnight-Freight]

I've weathered my track (rail sides and sleepers) using cheap acrylic paints I already had and achieved a finish I am now happy with. I didn't prime the plastic sleepers first and have noticed on a couple of test pieces when I soak the ballast with a diluted pva mix it's lifting the paint off of the sleepers. I guess this was maybe inevitable but I didn't think about it at the time. Obviously I don't want this to happen or to have to re-paint now so I was thinking of giving the track a coat of something like Humbrol matt varnish before I ballast. 

Is this the best way to go or are there any other suggestions to make sure I don't lose what I've already done? 

[Right Away]

Often, new ballast requires weathering itself, unless you're aiming to replicate fresh PW work.

A weathered approach after ballasting could solve your original paint issue.