Nicotine stained walls are one of the worst kind of stains you can have on your walls. Nicotine stained walls and ceilings from years of heavy smoking can seep deeply into the pores of the drywall leaving what may seem like permanent stains and odor. If you have ever encountered nicotine stains and simply tried to paint over them without taking the proper preparations you may have noticed the stains bleed back through the paint. The reason nicotine bleeds through paint is because nicotine is highly soluble in water and most interior paints are water based. The only way to cover nicotine stains is to CLEAN the surface and prime the surface prior to painting. The best cleaning solution to use is TSP (Trisodium Phosphate) when using TSP it is important to remember to wear gloves. Mix 1/2 cup of TSP with 1 gallon of warm water and gently scrub the surface you are painting with the solution. I find it best to scrub from the bottom up to eliminate as much streaking as possible. After you clean the surface the next step is to use a primer. The best primer to use is an oil based primer. Oil based primers are very smelly and take a long time to dry. If you do not want to deal with the smell or wait 24 hours for the primer to dry then I recommend using a few coats of a stain blocking primer such as Killz. Once the surface is cleaned and primed then you may proceed to paint your surface with the paint of your choice.