Even though latex paint has become the paint of choice for most projects, oil-based paint still has its place. There is no substitute for oil-based primers and solid stains for some applications. A sprayed oil paint on trim, doors and cabinets gives a superior, flawless, glossy finish. Spraying with oil paint can be challenging. You'll need different spray tips because the viscosity is different to latex paint. Oil paint over-spray will float farther and stay wet longer, so it's even more critical to properly mask and protect adjacent surfaces.
Paint Spray Tips
You can spray oil paint with either a conventional sprayer, an airless sprayer or an HVLP (high volume low pressure) sprayer. The most important component in getting a flawless finish is the spray tip. Oil paint is thinner than latex paint, and using your latex tip will cause the oil paint to go on too heavily, creating drips and runs in the paint. Paint spray tips are numbered with three digits. The first number is half the fan width in inches, and the last two numbers are the orifice size in thousands of one inch. So, for spraying oil based paint on trim, you would probably use a 213 tip for a 4 inch wide fan with a fine finish orifice of .013 inches.
Keep it Clean
Using clean, properly flushed spray equipment will virtually eliminate clogging of the spray tip. Flush the sprayer with clean mineral spirits before running the paint through it, and be meticulous in cleaning it at the end of each day. This includes flushing or changing the filters after each use---most sprayers are designed to make this a very easy job and it should take just a few minutes.
Strain your paint before using it, even if the can is brand new. Either use a mesh paint strainer, or a pair of clean nylons. While working, keep debris from falling into your paint by draping a clean piece of plastic over the paint and spray rig.
Latex paint over-spray is heavy, relative to oil over-spray. Unless it's windy, it doesn't drift far and as long as the air is warm, it often dries to dust before it hits the ground. Oil paint is lighter and dries slowly. This means it can drift across the street on a light breeze, settle on your neighbor's car and stick. When spraying oil paint outside, make sure cars, mailboxes, lawn furniture and anything else is either moved at least 50 feet away, or covered with plastic or drop cloths.
Invest in a hand masker, tape and enough plastic and masking paper to completely mask off all adjacent surfaces. A hand masker allows you to apply tape and masking materials with precision and speed.
Oil-based paint no longer contains lead, but it's still potentially harmful to breathe the fumes. Wear a mask or respirator and open windows and use fans for ventilation. Close or seal heating and cooling vents in the rooms you are working in to prevent the fumes from traveling through the duct work. Don't smoke, and do turn off pilot lights because the paint fumes can be inflammable.
Every airless spray gun has a thumb-operated trigger lock. Engage the lock whenever you're not spraying and never point the gun at any part of your body, or at anyone else. The paint comes out of the tip at extremely high velocity and can deeply penetrate skin. If this happens it is a medical emergency, so treat a spray gun as if it were a real gun.
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