How to Apply Boiled Linseed Oil As an Exterior Primer When Painting

Prepare the surface. Take off any removable elements you don't want to prime, such as hooks or knobs. Clean the surface. A pressure wash is great for big surfaces, but small jobs can be done with a sponge and cleaner in a bucket. Let the surface dry. Repair uneven areas or holes with outdoor-rated fillers or cement and wait for that to dry.

Using the sandpaper, scrub the surface you will be painting to clean it of dirt, old finishes, adhesives and rust. Grind the surface down to an even grain. Use a towel to sweep off dust and dirt.

Protect areas you don't want to prime. Use painter's tape to cover any edges and surfaces you don't want to cover with primer. Examples include glassy surfaces or already finished surfaces, unless you intend to paint over them as well.

Start priming. Apply the boiled linseed oil primer to the surface. Use a roller brush for wide, flat surfaces and the brush for edges and smaller surfaces. Maintain a thin, even coat.

Mix the additive and the primer. Over time the linseed oil primer may begin to set--that is, thicken and lose its workability and penetration. Brush and roller strokes will be more evident; it may become difficult to maintain an even coat. There should be information on how much additive to mix with the primer on the additive's product label.

Continue priming. Roll and brush the primer onto the exterior surface as before.

Finish and dry. If the tape is not too deep under the layer of primer, you can use it to guide the cover stain as well. Drying times will vary, but as the primer is an oil, it will take somewhat longer to dry than latex finishes.