Tips for Painting Varnished Wood
Can You Paint Varnished Wood?
Painting varnished wood by hand is really timing consuming, but when done correctly, looks awesome. Most stained interior trim is coated with a protective finish that doesn't bond well with paint. Stained and varnished wood needs to be totally sanded, cleaned, and primed for the best paint adhesion.
Painting stained trim in a home is what this article mostly refers to, but most of the paint prep is the same as painting varnished paneling, furniture, or doors.
Clean the Surface
The surface should be thoroughly cleaned before sanding and priming. You can clean after sanding, but I usually do it before sanding. Most people reach for a de-glossing agent when cleaning, but there's no need to use harsh chemicals that are hazardous to your health. Traces of these chemicals can remain on the surface of the wood, causing fish-eye and bonding issues with paint. Simply use Dawn dish soap to rid the surface of dirt and debris.
Cleaning is not meant to take the place of sanding. Although liquid sanding products, like Klean Strip and Gloss Off, claim to remove gloss without sanding, these products don't work well and leave residue on wood. Cleaning is only meant to remove dirt and grease from the surface. Sanding will break down the gloss for a strong bond with primer.
Sand the Varnish
Sanding definitely sucks, but it's a must when prepping varnished wood for paint. Sanding wood dulls the glossy finish of varnish so the primer and paint sticks well without issues.
For sanding stained base board and frames, I use a brand new 3M sanding sponge. A sanding sponge is very coarse and works well for removing varnish and exposing the raw wood underneath. If you want to use sandpaper, wrapping the paper around a sanding sponge makes it a lot easier to maneuver into corners and along trim edges.
For table tops and larger, flat surfaces, a random orbital sander is the most efficient method for sanding. Load the sander with 180 to 220 grit sandpaper. Use a tack cloth to remove excess sanding dust before priming.
Best Primer for Varnished Wood
When painting over varnished wood, my go-to primer is the oil-base product Cover Stain by Zinsser. Yes, it's oil and it smells horrible, but it seals wood to prevent bleed-through from tannin. Cover Stain is also an excellent bond coat for paint. It dries in one to two hours.
Another excellent option is the shellac primer BIN by Zinsser. This product is very thin and messy to work with when using a brush, but for spraying, it sprays really well and levels nicely over wood. It also dries in thirty minutes and can be top coated in about one hour. Like Cover Stain, it seals wood and bonds really well with paint.
Another primer that can be used to prime varnish is Pro Block by Sherwin Williams, also an oil-base primer. This product also seals wood and provides a bond coat for paint. The smell of this primer is really bad. A respirator and ventilation is a must.
There are latex products that can be used to prime varnished wood, but in my experience, they don't perform as good as oil-base primer. Latex primer won't prevent tannin bleed. Oil primer smells terrible, but it works the best.
Use Protective Masking Paper
Whether you're brushing or spraying primer on interior wood, it's very messy. A brush stroke will fling sprinkles of primer all over flooring, which is hard to remove if it dries. When painting trim, the flooring beneath the substrate should be covered with tape and masking paper.
The easiest way to mask flooring next to base board and door frames is with a 3M hand masker. You simply equip the masker with tape and a roll of masking paper and the machine simultaneously attaches both to the floor in one pass. This not only protects the floor, but it also allows base board to be painted quickly without having to carefully cut-in.
Painting Over Stained Wood
After the surface has been cleaned, sanded and primed, using an oil-base primer, the wood should be lightly sanded and then painted. Painting stained wood usually takes at least three coats of paint after one coat of primer.
The product I use the most for painting wood trim, frames, cabinets and furniture is Pro Classic acrylic latex from Sherwin Williams. I like the semi-gloss finish. This paint contains levelers that allow it to level evenly over a surface when sprayed or applied with a brush. The re-coat time is about four hours. For painting trim, a 2 1/2-inch angled brush is a good size.
If you're faced with the task of painting all the stained trim in your house, you should consider using an airless sprayer instead of doing it by hand. Spraying the wood will easily cut the time in half and look better. It's very tedious work, but if you take the time to do the job correctly, the paint will be very durable and look amazing.
Painting vs. Replacing
In the case of painting stained trim, hiring a painter is cheaper than hiring a carpenter to replace the wood with paint-ready trim. The downside to painting stained trim white is that it shows dirt more than stain does. Glossy paint also makes damaged wood and imperfections more noticeable.