# Why is brown stain bleeding through my paint?

Canonical: https://colorswatchlab.com/guides/wood-tannin-bleed/
Author: Color Swatch Lab Editorial Team
Published: 2026-11-04
Updated: 2026-11-04
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> Brown, tan or yellow stains that follow the grain, or that sit in the shape of a knot, are usually tannins: natural acids in the wood that water carries up through a coating that does not trap them. Cedar, redwood and mahogany do this most often, and so do knots in other woods, including pine. Sherwin-Williams says the same thing can happen on any wood, and that painting the wood while it is still damp does it too. Wash the stain off with a cleaner made for that job, let the wood dry, and seal it with an alkyd (oil) stain-blocking primer or a shellac primer before the finish coat. A shellac primer such as Zinsser B-I-N is for spot-priming knots and exterior bleed, not for coating a whole outside wall. Severe bleed can need a second primer coat. Even a correct primer can still let some tannin through on new wood.

## Is it tannin, a leak, or yellowed paint?

Sherwin-Williams describes tannins as acids that occur naturally in tree sap. They can sit quiet in dry wood and start moving again once the wood gets wet. If the paint on top was not made to trap them, they come through as brown, tan or yellow stains. Behr’s problem solver describes the same mark: a brownish or tan discoloration that migrated from the substrate through the film, most often on redwood and cedar, or over knots in other species, and easier to see in light colors. The shape of the stain is the clue. A knot prints a round or oval spot. Cedar and redwood often streak with the grain. A stain that shows up months later, on a film that is still stuck down, usually means water is still moving through the wood and carrying more tannin with it.

| What you see | Likely cause | What to do |
| --- | --- | --- |
| A brown or yellow spot the shape of a knot on pine trim, a door or plywood | Extractives in the knot | Spot-seal with a shellac or alkyd stain-blocking primer, then the finish paint |
| Tan streaks on new or bare cedar, redwood or mahogany | Tannin-rich wood under a coating that does not trap tannin | Clean, dry, then an alkyd wood primer, or shellac on the worst spots and a full primer over that. A second primer coat if the first still bleeds |
| The same stains months later, and the paint is still attached | Moisture inside the wood, carrying tannin to the surface | Find and stop the water, let it dry, check that the film still holds, then seal and repaint |
| A brown ring on a ceiling, with no wood showing | A leak staining the paint, not tannin from a board | Fix the leak, dry it, then a stain-blocking primer. See [yellowing and water stains](https://colorswatchlab.com/guides/why-is-white-paint-turning-yellow/) |
| White oil enamel turning yellow in a closet or behind a picture, evenly | The alkyd paint itself aging, not the wood under it | That is [yellowing](https://colorswatchlab.com/guides/why-is-white-paint-turning-yellow/), and washing will not turn it white |

## Why ordinary latex lets it through

Sherwin-Williams says tannin staining is most common on redwood, cedar and mahogany, and over knots, but that any wood can do it. Painting with a latex that is not designed to trap tannins, or painting wood that is not fully dry, is how the stain reaches the finish. Behr lists three causes that match what people actually did: the surface was not primed and sealed, the primer was not stain-resistant enough, or moisture escaping through an exterior wall carried the stain up. Benjamin Moore’s Fresh Start primer chart marks cedar and redwood as a case where an acrylic primer can be used, with a footnote: severe tannin bleeding may need a second coat of primer or an alkyd primer. The same chart describes their exterior alkyd deck-and-siding primer as the one with stronger tannin suppression on new and weathered wood. The everyday split between acrylic, alkyd and bonding primers is in [when to prime](https://colorswatchlab.com/guides/when-to-prime-before-painting/).

Sherwin-Williams adds a limit that is easy to miss. Even with the right prep and the recommended products, tannin can still bleed, especially on new wood, and it can do that under either a latex or an oil topcoat. A stain that returns after a careful job is not proof you bought the wrong brand of wall paint. It is a reason to seal again, and to check whether the wood is still getting wet.

## Shellac for knots, alkyd for the boards

The data sheet for Zinsser B-I-N shellac-base primer (BIN-03) is specific about the job. It lists sealing bleeding knots, sap streaks and tannin bleed, and it names cedar and redwood among the woods it is applied to. It also draws a hard line on the outside of a house: use it to spot-prime persistent bleed from knots and sap streaks, then prime the whole surface with a water-based or oil-based primer. The sheet says it is not for a whole exterior surface, and not for floors, decks, or anything that stays wet. Interior use can be a full prime. On new cedar and redwood, that same sheet says to let this primer dry 24 hours before the topcoat. Its ordinary clock, at 70°F and 50% relative humidity, is shorter: dry to the touch in 20 minutes, recoat in 45 minutes, full adhesion and hardness in 1 to 3 days. Cooler air, higher humidity and tint stretch those times. Do not thin it. The sheet lists a maximum VOC of 550 g/L, so this is a solvent-borne shellac, not a low-VOC wall paint. What that grams-per-liter figure means is in [low-VOC paint explained](https://colorswatchlab.com/guides/low-voc-paint-explained/). Ventilate, and keep the can in the temperature range on the sheet.

Application limits on that sheet are tighter than “any dry day.” Air, primer and surface should be between 0°F and 90°F, relative humidity below 70%, the surface at least 15°F above the dew point, and the wood’s moisture no higher than 12%. Those outdoor dew-point and temperature ideas, for ordinary exterior latex, are in [exterior painting weather](https://colorswatchlab.com/guides/exterior-painting-weather/). The sheet also says not to wash the surface with TSP before this primer. It calls for an ammonia-and-water wash or another cleaner the label allows. That is a rule for this primer, not for every paint job in the house.

## How to stop a stain that is already showing

- **Test for lead before you sand or scrape.** Trim and siding in a house built before 1978 may have lead paint under the newer coats. The shellac-primer sheet repeats the federal warning about lead dust. Follow [lead-safe painting](https://colorswatchlab.com/guides/lead-safe-painting/).

- **Wash the stain, then dry the wood.** Sherwin-Williams says to wash tannin off with a deck-and-siding brightener, following that product’s label. Behr says to remove the stains with oxalic acid or a wood cleaner made for tannin stains, then let the surface dry at least 48 hours, longer if the weather is damp. Use the cleaner’s own directions. Do not mix a homemade acid bath from a guess.

- **Stop the water if the stain came back later.** Sherwin-Williams says a later stain on an intact film is usually moisture inside the wood. Find the leak, the uncaulked joint or the wet end grain, let the wood dry, and check that the old coating still adheres before you coat it again. Paint that is already letting go is [peeling](https://colorswatchlab.com/guides/why-is-paint-peeling/), and primer will not glue it back.

- **Seal, then paint.** Spot-prime knots and the worst exterior streaks with a shellac primer, then prime the field with an alkyd stain-blocking wood primer or the primer the topcoat maker names for tannin. Behr says to prime all six sides of a board when you can, which is the back, the edges and the face, and to add a second primer coat in extreme cases after the first has dried. Benjamin Moore’s footnote is the same idea: a second coat, or an alkyd, when the bleed is severe.

- **Then the finish.** Two finish coats at the spread rate on the can, not one thick coat piled on to hide the stain. A heavy coat is how [paint sags](https://colorswatchlab.com/guides/why-is-paint-sagging/).

Product names above are examples of a primer type, taken from the pages and the data sheet cited. They are not a ranking, and this site is not affiliated with those brands.

## What still goes wrong

- New wood can bleed again. Sherwin-Williams says so outright. If a light topcoat stains after a correct prime, spot-seal and prime again rather than adding more finish paint on top of the stain.

- A water-based primer that “suppresses stains” on ordinary walls is not automatically enough for bare cedar. Read the footnote on the can, and plan on an alkyd or a second coat if the first one discolors.

- Painting over a stain without washing it leaves the color in the film you are trying to hide. Clean first.

- Interior paint on exterior wood fails for more than tannin. That split is [interior versus exterior paint](https://colorswatchlab.com/guides/interior-vs-exterior-paint/).


## FAQ

### Why did my white paint turn brown over a knot?

The knot is full of natural resins and tannins. Water moves them through a coating that does not seal them, so the knot prints a brown or yellow spot on the paint. Spot-seal it with a shellac or alkyd stain-blocking primer before the finish coat.

### Will latex primer stop cedar or redwood bleed?

Sometimes, and sometimes not. Benjamin Moore marks an acrylic primer for cedar and redwood with a footnote that severe tannin bleed may need a second coat or an alkyd primer. Sherwin-Williams says to seal tannin with an alkyd or oil primer, or a coating designed to trap tannins, and that bleed can still happen on new wood.

### Can I use shellac primer on the whole outside of the house?

Not the shellac primer whose data sheet we checked. Zinsser B-I-N is for spot-priming exterior knots and sap streaks, then a full coat of a water-based or oil-based primer. The sheet says not to use it as a whole-surface exterior primer, and not on floors or decks.

### How long do I wait to paint over a shellac primer on new cedar?

On new cedar and redwood, the B-I-N sheet says to wait 24 hours before the topcoat. Its ordinary recoat time, for other surfaces at 70°F and 50% humidity, is 45 minutes. Cool or damp air takes longer. Your can’s label decides if it differs.

### The stain came back months after I painted. Did the primer fail?

It may be water, not a bad primer. Sherwin-Williams says a later stain on a film that is still intact usually means moisture inside the wood is carrying more tannin out. Stop the water, let the wood dry, and seal again. New wood can also bleed even after the recommended primer.

## Sources

- [How to Fix Paint Tannin (Sherwin-Williams)](https://www.sherwin-williams.com/en-us/project-center/maintenance-repair/paint-tannin)
- [Tannin Staining, paint problem solver (Behr Pro)](https://www.behr.com/pro/resources/paint-problem-solver/paint-problem-solver-detail/tannin-staining)
- [Fresh Start Premium Primers (Benjamin Moore)](https://www.benjaminmoore.com/en-us/interior-exterior-paints-stains/fresh-start-premium-primers)
- [B-I-N Shellac-Base Primer technical data BIN-03 (Zinsser / Rust-Oleum)](https://www.rustoleum.com/~/media/DigitalEncyclopedia/Documents/RustoleumUSA/TDS/English/CBG/Zinsser/BIN-03_B-I-N_Shellac-Base_Primer_Ultimate_Stain_Blocker_TDS_1.ashx)
- [Reduce the Risk of Lead Exposure at Home (US EPA)](https://www.epa.gov/lead/protect-your-family-exposures-lead)