First, you want to wash it thoroughly with Dirtex (strong solution). Second, sand it with 180 grit sanding sponge until it is dull. Remove sanding dust with vacuum and damp sponge. No primer is required (unless making drastic color changes) when repainting clean, dull, alkyd paint with high quality acrylic enamels.

wryorwhite -- Don't be scared by all this talk of yellowing. It's exaggerated. Bear in mind that oil-based paint was essentially all that was used in American homes through the 1980s -- so unless you're a teenager, you were around when any house you'd walk into (including the one in which you grew up) had its walls painted with oil-based paint. Trust yourself and your own experience...do you ever remember walking into a house and thinking to yourself "My, these walls are awfully yellowed!"? I sure don't. When's the last time you've heard someone say "Oh, look at those walls! They've gone from looking like snow to looking like Big Bird! This is certainly oil-based paint!"? Never. Yes, oil-based paint yellows very slighly with time. So do all oil-based products, including the clear polyurethane with which wood floors are most often finished. This "yellowing" effect is minimal, and it's not something that jumps out at you or is offensive or anything like that. You have to actively look for it, and the only people who do that are (a) homosexuals, and (b) people who work in the marketing departments of latex-based paint companies. The drawbacks of latex-based paint have largely been resolved in the past few years. The latex-based paints of 2008 are a far cry from the ones of 20 years ago. This is especially true with the high-quality brands like Pratt & Lambert. Modern high-end latex pains bond to drywall well, hold up to moisture and cleaning well, etc. However - latex-based paints aren't as good as oil-based paints when it comes to moisture and dirt resistance, standing up to scrubbing, and bonding to wood. They never can be, because oil (unlike latex) naturally resists water, and naturally soaks into wood (rather than just sitting on top like a skin). Think of what happens when you mix oil and water -- they don't mix; instead, they just separate and keep apart. So moisture and dirt don't bond to the oil-based paint, so it's very easy to clean without damage. In addition, oil-based paint soaks into wood -- unlike latex-based paint, which forms into a skin that you can peel off. This is one of the big drawbacks of using latex paint on high-traffic wood items (like kitchen cabinets). My house has latex-based paint on the walls and ceilings, and oil-based paint on all the wood trim (including the doors and windows and cabinets) -- this is a time-tested and popular arrangement, and it has held up very well for me and my neighbors. Speaking of polyurethane -- there are two types, oil-based and water-based (latex-based) - same as paint. ALL of the manufacturers -- Minwax, Cabot, etc. -- recommend strongly in favor of using the oil-based polyurethane on floors. It's tougher, it holds up better to traffic and moisture, and this "yellowing" effect that the self-proclaimed experts yammer on about are so minimal as to be non-existent. The same is true with the oil-based vs. water-based (latex-based) paints. Again, trust yourself and your own experiences -- how many times have you walked into a home and thought to yourself that the painted walls and ceilings, or the wood floors, were yellowed?

1:1 is a pretty heavy dilution. I think the manuf. used to recommend no more than 25% thinning. The newer low-voc oil primers by Moore state clearly "Do Not Thin" but I have disregarded that command many times, seemingly with no adverse effects? You can also make oil paint more brushable by thinning with penetrol, or some boiled linseed oil for that matter. Casey

The traditional answer is that an oil based primer should be used because tannin is water soluble. However, some of the new acrylic, water based primers, such as Kilz Premium, will stop tannin bleed, provided that 18 hours of cure time is given before top coating with a water based paint. Some of the new "paint and primer" paints are also stain blocking. Two coats of the paint itself will stop tannin bleed, but again, only after an overnight cure time before applying the finish coat. And yes, water based paints can be applied over a thoroughly dried oil based primer.