A paint job that quickly fails can be distressing, leading one to think maybe it's the paint at fault. Do-it-yourselfers often overlook the importance of proper surface preparation. The most important step of all is applying primer. It's purpose is to seal the surface so that the top coat goes on smoothly and adheres well. Primers also hide stains and seal porous surfaces. They should be used on raw, unfinished surfaces and painted areas that were sanded or patched. There are many types for special purposes, so check what you need for your specific project. If you want an education, just spend some time this weekend in the paint department of any hardware store or home center; it won't be long before some homeowner brings in a half can of paint complaining that it bubbled, cracked and-or is peeling. The patient clerk will be sure to reply, "Sir, it ain't the paint!" Remember -- preparation and primer will save you the trip. And that's the On The House Tip for today.