I have completed a carving and used boiled linseed oil mixed with burnt umber to antique and finish the piece. It has not darkend areas (like facial wrinkles) as much as I would have liked.

Now that I have an oil finish what are my options for adding depth to this piece? Or, should I just chalk it up to experience, forget this piece and move on to another carving?

I had tried linseed oil several years ago with results that were less than satisfactory, to me. From now on I will stick to the few finishes that I have used with success.

You might try a Watco Dark wax (liquid) finish. One of our club members mixes dark with natural for a very nice antique effect over acrylics.
Just brush it on and wipe it off all the high spots.

Have you tried Bartley Gel Stains? They are linseed oil based and you can use them to create the look you desire very easily. You just rub or brush them on. The longer they sit on an area the darker it gets.

http://www.bartleycollection.com/finish.htm

I usually put one two separate coats of boiled linseed oil with two days drying time between. If I want to get a sheen to the piece after that I use regular wood floor paste wax well buffed.
If I want a little darker color I use Watco Danish Oil with a premixed stain after I have used the boiled linseed oil. The Danish Oil puts a harder finish on it than just boiled linseed oil by itself. This harder finish buffs up better with wax or polish.

Always wipe B.L.O.off after 20 minutes or so and reaply after that another coat ,not more than 2-3 always wiping off in between and enough time after for curing until it has no more smell than it is cured. hope it helps
Alice

[squbrigg]

After oiling , you might try just a dark stain, wipe on, wipe off, possibly a couple of layers, until you get the effect you want. The colour of stain can depend on how dark you want the wrinkles and the type of wood you are using.

When dry, I use a paste wax to seal it all. Couple of layers and lots of polishing. Try it on some scrap first. Works for me.

Bob