As far as the recipe or process goes, here are the steps, in case anyone is interested.
I start by using a black charcoal pencil on the edge of the boards. Then after they are glued down, I lightly sand. This smears the excess charcoal on the edges around and into the wood grain. This makes the wood grain stand out, which is my goal. Then I clear coat to seal the charcoal in the wood grain. Afterwards I lightly sand with steel wool. Then I add the brown stain and wipe with a rag to average the color. Once dry, I lightly sand again with steel wool to weather the boards. If any areas are too light, I add some brown stain and wipe with a rag to average the color. Of course I want some variation so it looks more realistic.
Due to the many steps, there will always be variation. If I wanted consistency, I would first add pre stain. But this is not the look I’m after. I want a slightly used or weathered deck that has been worn with use and age. But not so worn that it looks out of place with the rest of the ship. The walls and railings I want less wear. Ladders and decks should show some wear. That’s my logic anyway.