With the recent marketing of “paint and primer in one” type products, a lot of confusion is out there. Primers are made specifically to seal the surface, block a stain and/or improve adhesion. Top coats are made to add durability and beauty to the surface. These all in one products can work if they are used in the correct situation. Benjamin Moore's Regal Select is a great example of a "paint and primer" that works well.  If you are putting latex wall paint over latex wall paint you don’t need a primer, providing  there aren’t any bleeding stains on the wall.  Any time you have an ink stain or a water stain you need to use a stain blocking primer such as our Fresh Start Multi-Purpose Primer 024. When painting bare wood use our Alkyd Enamel Undercoater C217. This primer penetrates into the wood for maximum adhesion plus it sands very easily for a smooth finish. When painting over new sheetrock a primer will not only improve adhesion it also allows the topcoat to flow evenly. When working outside a primer seals bare wood for a longer lasting paint job. Primer will also seal up badly weathered paint so the new topcoat will last longer. There are too many situations to list in a short blog. The ugly truth is this: Primers typically cost less than paint, they provide a needed service or solve a particular problem, and they increase the life of the paint job. Don’t skimp by using the incorrect product, it will cost you more in the long run. Ask our professionals about your project and we will get you the right product, even if it is just a quart of paint.