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I built some pine shelves. They're pretty, but I don't want them to darken. I'm told I can apply polyurethane to ensure they stay nice and bright.

My question is this: do I need to apply some kind of stain, even "natural," before polyurethane? Or can I sand and then apply the polyurethane directly?

If it's okay to apply polyurethane directly, can I sand 60-grit and then do poly? Or do I still need to work up to 200-something-grit?

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    Pine isn't the best at taking stain to begin with.
    – DA01
    Aug 21, 2012 at 4:52

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There's no need to stain if you like the color as it it. Staining won't do anything for you and will just take more time. Chances are that your boards might already be pretty smooth, so I'd start with fine sandpaper (200 and above), not rough like 60 grain, except on edges that have been cut. If you use 60 grain on a surface which is already smooth you'll make it rougher and have to work hard just to get it back to where it was before you started!

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    Water based urethanes tend to take much longer to "amber". Oil based coatings even clears will eventually amber or turn yellow with exposure to sunlights.
    – mikes
    Aug 21, 2012 at 10:34
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Even with a clear varnish pine will go yellow/orange with age, so adding a colour will make it darken even more quickly. A couple of coats of clear varnish will seal the wood and stop it darkening too quickly, but you may find you have to refinish the shelves in a few years to return them to their current colour.

As DA01 notes in his comment, pine is difficult to stain as different parts absorb different amounts of colour resulting in a patchy, mottled appearance.

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Just varnish. Sand with 220 sandpaper. If the boards aren't smooth enough, start with 150 and work up to 220. Put on several coats of varnish (I would say at least three) and sand lightly between coats with 220 sandpaper.

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