Wash for SIVb LM adaptor panel fillets?

[Michael Morris]

 I'm building a model of the Apollo 7 spacecraft in orbit next to the SIVb upper stage. The inside 'petals' on this rocket stage have some rust colour fillets between the metal skin panels (see photo). 
I'm planning on modelling this using scribed panel lines, as trying to recreate these as raised features in 1/144 scale is beyond my skill level.  The plan would be to recreate the fillets using a panel wash, what would you recommend I use?

Thanks