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Pine and some others will bleed through. You need to seal the knots before you paint em. Cover them with a thin layer of shellac or epoxy, reprime, then paint.
Knots in wood come through paint because they contain resins and oils that can seep through the paint over time. These substances can cause discoloration and stains, especially if the knots are not properly sealed before painting.
No KILZ 2 will not work on knots. We recommend KILZ Original, Complete or MAX for this kind of job.
Epoxy has a place in every woodshop and it can be a handy multitasker. It is important to add that with the particular epoxy that Im using, you need to pour it in layers no more than 1/4" deep when filling large voids. Wait for each layer to cure before pouring the next one on top.
If you're aiming to paint your wood cabinets to achieve a flawless, modern finish with zero grain, a combination of a good quality high-volume solids grain filler and a high-build primer is the way to go. These products work in harmony to hide wood grain as much as possible and at the same time, block tannin bleed.
Ronseal Knot Block Wood Primer and Undercoat is everything you need in one tin. It completely blocks wood knots and resins and covers strong colours and dark marks. It won't yellow, crack or peel and will be ready to paint over in as little as four hours.
Start with coarse 80-grit sandpaper in a manual hand sander or power sander. Using enough pressure to remove the paint but not so much that it damages the wood. Move to medium 150-grit abrasive and finish with fine 220-grit, brushing away dust from the surface each time you change paper.
If you're in the middle of a paint project and you start to experience bleed-through, here are a few tips and suggestions to try: Stop painting and let your piece dry completely. Apply 1-2 coats of Dewaxed Shellac or BIN Shellac Based Primer over the bleed-through.
The best product on the market (in our opinion) to help prevent bleed through on your paint job, is Zinsser BIN primer with “Synthetic Shellac”. You can find it HERE. The most important part of this primer is that it contains the Shellac component.
Spot prime knots and sap streaks with Zinsser paint B-I-N Primer-Sealer.
Priming Knotty Pine
We chose Zinsser BIN oil-based shellac primer. This stuff is the absolute best. It coats and seals everything in and, because it's a shellac, it fully encases any residue to prevent it from surfacing. We also used BIN to prime our cabinets in our rental house and it worked like a charm there too.
Ideally one coat of primer on the knots, then apply paint like normal. You can always put two coats of a stain blocker on there, then paint.
Polyprep 205-112 sealant is also used to close the pores of wood, thus reducing the number of applications needed for a good appearance. Shellac is the best sealer.
Remember to use a knotting solution or shellac-based clear coat to seal the knots. Pigmented primer will show right through the stain, even if you use multiple coats. Apply as many coats of stain as it takes to achieve your desired depth of color.
Apply a uniform coat of KILZ 3® PREMIUM Primer to your cabinet frames and doors. The thicker formula fills in imperfections in the wood grain of your cabinets, creating a smooth surface for paint application.
If the stain bleeds through the topcoat, apply a second coat of primer and test again before top coating the entire area. If bleeding continues, a longer dry time is needed before top coating. When you start with primer, blocking light and heavy stains doesn't have to be a challenge!
Rinse with a pressure washer. Allow the surface to dry thoroughly for at least 48 hours (depending on the existing weather conditions). Prime the stained area with a top-quality, stain-blocking wood primer. If severe staining exists, apply two coats of primer.
After removing the knot, clean any loose bark and debris from the knothole and the knot using a brass wire brush. Mix up a small amount of epoxy and spread it liberally on the outside of the knot and reposition it in the board. Spread additional epoxy to fill any remaining voids.
Our recommendation for the best wood filler is the Toupret Extrem Wood Filler, also from Toupret's filler range, as it provides a comprehensive repair system for interior and exterior wood, plus it is designed to repair both large and small gaps, cracks and holes.
To avoid this happening, you can gently apply some wood glue around the edge of the knot.