I stained some red oak using vinegar when making trim for my house. It's supposed to make it look like old gray barn wood. It didn't exactly turn gray but I liked the results so I stuck with it.
[IMG]http://i305.photobucket.com/albums/nn214/jfnar/house/IMG_02001_zps5teel20o.jpg[/IMG][IMG]http://i305.photobucket.com/albums/nn214/jfnar/house/IMG_0218_zpsssgvuva5.jpg[/IMG]I used red oak trees that were knocked down to make room for the house. I cut them on a HF bandmill and planed it until just a few saw marks were left. It was a lot of work but nobody else has anything just like it. I plan to make bed wood for my flat bed and my 9' stepside bed out of white oak. It's more durable for outside applications. I don't know what it will look like but I plan to try the same staining method. You just soak steel wool in vinegar over night and then remove the steel wool. I used a spray bottle to apply it. It darkens the wood in a couple of hours. Then I sprayed clear polyurethane over it with my $10 HF HVLP sprayer. I might use a different clear coat for my bed wood. I haven't decided yet.