Even though oil primer smells bad and can be messy to work with, it's the best option for painting over polyurethane because it soaks into wood to form a seal without raising the grain like a latex primer would.
Apply oil-based paint primer. Using a primer will give your paint a better surface to stick to. The primer also keeps any stains on the wood from coming through the paint.
NOTE: Zinsser Bulls Eye 1-2-3 is not recommended for painting over varnished or polyurethane surfaces.
We recommend using Zinsser Bulls Eye 1-2-3 for glossy surfaces like varnished wood. Zinsser Bulls Eye is a 'bond coat' primer that's great for hard-to-stick surfaces as it offers excellent adhesion without sanding.
You can paint over varnished wood as long as you use the right materials and painting process. The best paint to use is a water-based acrylic one. If you're using an oil-based paint only use an oil-based primer, not an acrylic one. “Sweet, this means it can be done!
Can I use any type of primer on varnished wood? For the best results, use a water-based primer that adheres to varnished surfaces without the need for sanding.
If everything was done correctly, your polyurethane surface should be ready for paint without any issues. Water-based paint works just fine if your surface is primed correctly, however it's recommended you use oil-based paint for a more superior, long lasting finish.
If you have various stains, shellac Bonding primer is the ideal choice. It can be used to cover rough surfaces and old varnish as well as metal and ceramic.
Zinsser BIN is a shellac-based paint, Bullseye 123 is water-based. They're both adhesion primers and stain blocks, but each one is better for different jobs. For example, Zinsser BIN is better for blocking water stains and gripping to varnished wood. Zinsser Bullseye 123 can be used outside and works better on plastic.
When it comes to priming varnished wood surfaces, Zinsser's Bulls Eye 1-2-3 is a top contender. This versatile water-based primer-sealer is perfect for interior and exterior use and offers exceptional adhesion without the need for sanding.
Note that most polyurethanes do not adhere well to polypropylene, polyethylene, silicone or surfaces coated with fluoropolymers like Teflon.
There is no difference between the terms urethane and polyurethane. That might seem confusing, so here's a quick explanation. Polyurethane is a polymer. A polymer consists of repeating units that are chemically linked in a particular pattern.
KILZ Concrete & Masonry Bonding Primer is specially formulated to optimize the adhesion of masonry coatings. With proper application, this product provides a sound foundation for coatings with excellent resistance to water, alkali and efflorescence.
Topcoats are the final coats for use over primers or fillers. They are formulated to provide good adherence to the undercoat, the desired appearance (colour, gloss, structure) to the painted unit, additional protection from the weather and aid in other performance requirements.
“If you are looking for a primer that can stick to almost anything for both interiors and exteriors, Stix® has you covered.”
A 'bond coat' primer that's great for hard-to-stick surfaces, it offers excellent adhesion without sanding. Bulls Eye® 1-2-3 also prevents rust formation when applied over clean ferrous metal such as iron and steel.
(Note: Bonding primers are not recommended for use over peeling paint).
Choose a white, oil-based primer for the best coverage and adhesion to the polyurethane surface.
For bonding rigid PU, we recommend using polyurethane adhesives such as Araldite 2018 and Araldite 2028-1 and structural acrylics; Permabond TA4204.
Avoiding Sanding and Priming Prep
Surfaces with varnish, polyurethanes, or other sealants or finishes require sanding before any paint can be properly applied.
Crown Trade PX3. This is an oil-based adhesion primer. Again, it is perfect for priming varnished wood before painting over with additional products. You'll find it easier to use than Zinsser Bin, and better opacity.
Sanding Tips: No sanding is needed if you overcoat within 48 hours. Don't sand unless the most recent coat has dried for 24 hours. Use 320 grit to prevent scratches; sandpaper finer than 320 grit will not allow proper adhesion. Remove residue before reapplying.
In the category for best primer for painting stained wood, our results found two top performers. They are Sherwin Williams Extreme Bond Primer, and Behr Bonding Primer. These top two primers were the very best at bonding in both the 24 hour test and the 38 day test. A close 3rd was Stix from Benjamin Moore.