Somebody on Garden Junk suggested oven cleaner I think. Hopefully someone else will come in and suggest something else.

Is this furniture or a picture frame or a board and is there any finish on the wood?
I've burnt wood to make it look old. Use a propane torch and move it back and forth across the wood. When you burn the wood you're first burning out the soft Summer wood and leaves the hard Winter wood. You don't have to burn the wood a lot. Use a wire brush to remove charring. Then use a light gray stain. This is for a outdoor weathered look.
If you want the wood just to look worn or well used. Round all edges and add some scraps, dents and dings. Use chains to lightly hit the wood, screws laid on their side and hit lightly with a hammer give a nice look. Then stain or paint. Billie

You can make a mixture of 1/2 water & 1/2 white vinegar, put a piece of steel wool in it, cover and let it stand until it turns a rust brown color, probably about a week, then wipe/brush it on the wood. If the color is too dark adjust the amount of vinegar.

Michael

I have had good success by distessing the piece, then stain with a deck stain. The deck stain color I use is called weathered wood. I had to have it mixed at a local lumber yard.

Take a semi-transparent water based stain (gray) and dilute it to preference. Usually about a third full strength gives a natural look. Rub it on with a rag and don't be fussy. you can do a fence in an hour. You can mar the wood surface before staining if that's the look you want.

If you want it 'more weathered', after about a week of letting the stain dry, give it a blast at medium strength with a pressure washer. Then restain random boards to create a more natural weathered look.

You can also take it to your friendly neighborhood sandblaster. Blasting it will remove the softer areas & leave ridges of the harder areas.

'Pup

Hi!
I just finished a 'bird house' mailbox that I'll put in a copper tubing 'tree'. Of course, the wood was brand new so I mixed up some pale grey, black and sage green acrylic paint and diluted it with water. Brushed it on with a sponge brush and wiped the excess off with a paper towel. It looks pretty good. I don't know how long it will hold up in the weather but I hope by then the elements will do their job and make it look old.

I've weathered wood to achieve the look of "driftwood." If this is what you're looking for, here's how I did it. First I soaked the wood in a bucket of water & bleach (ex. "Clorox"). After a few days of soaking in this solution, I removed the wood & brought it outside to be "sun bleached" (this works best in hot summer sun). By the time the wood was thoroughly dry, if I wasn't satisfied with the "faux driftwood" look achieved, I repeated the process (as many times as necessary). Hope this helps!

Since everyone here is into chemicals, has anyone tried using the pickling stain for a weathered look??? Puppy4

If you want wood to really look old, texturing and/or shaping is the first step. Removing the softer grain, wearing the edges so they're rounded etc. Then you move on to colour, shade and tone depending on what effect you want. It could be a grey patina using the old vinegar and steel wool trick, or you may want it looking more like ships timbers, driftwood or antique like. This can be easily acheived wth stains and paints; apply a dark colour first then sand back to reveal the top wood. You can then apply a lighter tone or leave the top wood bare. For a more detailed explaination and results you might wan to take a look at howtomakewoodlookold.com