Is the current color a paint or stain? Is it transparent or solid color? Take a sample of the color you want to a good paint store and tell them it is either a paint or stain and tell the to make you up a product to correct the issue you have. They should be able to help. Either way, it will require sanding down most or all of the color on the door now and re-applying the new color, then finishing with a top coat. Test in a spot that is out of site or on a seperate surface that matches. Good luck.

after several unsuccesful tries with using strippers from local paint stores, I found this the product I linked to. I tried a bottle to give it a try. It worked great and so I bought a case to do the rest of the house. I had a couple decades of different oil based stains on redwood siding. I would give it a try. It would be best to try it on a sample area if possible. stain a board before it arrives. Let us know how it worked. Steve Here is a link that might be useful: Deck stripper

Different species of wood have different density/porosity, and different boards from the same species also do depending on tree growth factors and how the wood was prepped. So if at all possible, test your stain on some scrap or on an unobtrusive part of the piece to avoid surprises. Walnut is a wood that isn't particularly dense and is fairly porous, as you have discovered. It often is treated so that the blonder sap wood darkens to match the dark heartwood, and these two parts of the tree may be of different density.

WOw that is beautiful @Beth thanks for all the ideas. Nice job with your place too— thanks for the color ideas. My sofa is currently black, the table and chairs are medium teak but i have def another chair to reupholster- wonder about going light on all the furniture. I have lots of guests (like 25 at a time for classes sometimes) so worry about them staying clean but also not looking like so much black.I agree re blak slate at entry. Is the white stone i have called flagstone? Thanks for all your good ideas...i like the more clear, clean, lighter looks. Creamy soft furniture is nice, as long as I can find good ones with washable covers or keep it clean. I love that look. What a cool design artist!