*What Wood Finish Would Be Best to Use On an Existing Wicker Finish?

It would depend on whether you plan to use the furniture outside or under the protection of a roof. Theoretically, both water and oil-based products could be used.

For example, you could "antique" wicker with thinned Gel Stain to pop up the color depth on an aging piece of natural wicker. However, Gel Stain is not exterior-rated and is very thick, making it cumbersome to apply and wipe off on a highly textured surface such as wicker.

In general, we would recommend using water-based finishes on wicker because they can be spayed.

For an exterior finish, use our Milk Paint because it is an exterior rated paint, does not require a topcoat, and has superb adhesion and color longevity characteristics. If using in an exterior space, clear coating with Exterior 450 is optional.

One challenge would be proper preparation over an existing surface. Prep sanding is not effective because of all the varied surfaces of wicker, so thorough cleaning would more essential. Use a brush and a 50|50 mixture of denatured alcohol and water.  

The second challenge is that wicker moves when used so be prepared for cracking if you are using paint. Fortunately, a casual look is a popular one for porches and cracking would be acceptable.