Callout to the pros here! What is the secret to getting washes to form crisp panel lines? Here's my latest attempt on the Shadowcaster, compared to the exceptionally clean original job:

The wash is GW's Nuln Oil over a base of Vallejo acrylics with a thin cover of Testor's Dullcote sprayed on before washing. I tried to pin wash but ended up needing to dab over most of the panel lines since the wash didn't want to pull in by itself. I've done a light pass with clear medium and a fine brush to clean up some of the overspill, but there are still plenty of erratic blobs.
Would an oil-based wash work better?
Should I try something like airbrush thinner? (I've tried adding dish detergent. Small amounts make no difference. More makes things worse.)
Is this normal, and I just need to paint the panels a whole second time to clean things up?
Do I just need steadier hands?

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