Our old house was built in the 1960s and the kitchen cabinets were made out of native rimu timber. We replaced them with new melamine cabinets and I kept the native rimu timber to use for decorative shelves and chopping boards in our new home. Some of them had a few stains where oil had been spilled over 50 years of use, but that's part of the charm of using recycled timber. They also had screw holes in the ends and sides, and paint on some of the surfaces.
If you don't have used timber lying around like I did, you can buy it from a builder's recycling store. They have piles of used native timber and it doesn't even cost much. In Palmerston North there is the Rusty Nail timber recycling store in Longburn, but just check the internet for the nearest builder's recycling store to you.
I've used the Icon power sander because its inexpensive and does the job perfectly well. I used a medium sanding sheet (P80) and sanded the timber until the paint was removed and the oil stains were looking less obvious.
Next I filled in the old screw holes with timber filler and waited 30mins for it to dry before sanding. The timber filler is a pine wood colour, so I used tiny bit of wood stain to colour the filler a darker shade to match the rimu a little better.
ps - if you're going for the rustic/farmhouse shelving look then you might want to just leave the old screw holes unfilled to add to the charm :) Our house is fairly modern so I didn't want to go too rustic in case it looked out of place.
I mixed raw linseed oil and turps into a 50/50 mix in a jar and used a cloth to rub the mixture into the wood. It brings out a beautiful warm colour in the native timber:
These metal decorative brackets were $8 each at the hardware store. I love their rustic look and think they go well with the old recycled timber.
And here is the finished result. I really don't like the boring beige of the walls, but I think the rich colour of the timber will stand out if we add a warmer light clay colour to the walls later on. To make the shelves look a little more interesting, I placed the bottom one a little off to the right and the top is off the left. :)
Here is the shelf after I added a few more colourful items to it: