Sherwin Williams has a number of primers for any project. Their Problock oil is one of their best multi-purpose primers. The Problock comes in two versions: Latex or Oil. Be careful not to buy the latex version if you're trying to block out a stain. It won't work. You will definitely need the oil to ensure that it locks it out. I used Problock oil to take care of a stubborn water stain. It took care of it, and kept it from bleeding through the paint coat. Problock oil also comes in an aerosol version, which comes in handy when you have a quick small project to do. The only real draw back to this product is the odor, which means you will need to ventilate the area you are working on. Overall, this is a great primer that can handle some of the toughest stains. Quality It is one of the best oil based primers out there. Durability It's a primer. It's not meant to be durable. It's meant to make a paint-able surface, which it does. Coverage Covers great. It's used mainly to block out stains, but does a great job at hiding darker colors too. Ease of Appliation Super easy. Apply it which ever way works best for you.