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How to fix sap from Pine step treads?

I purchased 8 pine step treads from Bunnings Toowoomba. I gave them 2 coats of undercoat and 3 coats of Cabots step paint. They sat in my shed for a few weeks to cure.

I fitted them to the stringers and after a few days of hot weather the sap has come through and ruined the paint.

Was I wrong in thinking that they had been kin dried and treated ?How can I fix them and do I have any come back on Bunnings ?

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Comments

MitchellMc

Hi @Backyarder,

I’m so sorry to hear about your experience with the pine step treads and the sap coming through the paint. Treated pine does need time to stabilise and expel any sap before painting, which can take several weeks. Using an oil-based primer is also recommended, as it provides better protection against sap bleed-through compared to water-based coatings.

I suggest taking some photos of the affected treads and visiting your local store to speak with our Paint Experts and a manager. They’ll be able to offer advice on the best steps to fix the issue and discuss how we can assist you further.

Please let me know if you have any questions.

Mitchell

TerryKF

https://www.workshop.bunnings.com.au/discussion/comment/46943#Comment_46943

Hi Mitchell

I also purchased a set of the 6 tread, treated pine steps from Bunnings Gladesville.

After leaving the timber to dry for a couple of months we painted with Dulux weather-shield and assembled them.

Two months later they have about a dozen areas affected by lumpy, sticky sap.

I have scraped the lumps of sap - however would appreciate advice on what is the best treatment for next steps - no pun intended 🙂

Rgds Terry

EricL

https://www.workshop.bunnings.com.au/discussion/comment/88079#Comment_88079

Hello @TerryKF

Welcome to the Bunnings workshop community. It's sensational to have you join us.

Certain types of timber—such as pine, fir, and some varieties of eucalypt—naturally contain a high amount of resin. These woods can continue to “bleed” sap even after what appears to be sufficient seasoning time, especially if internal pitch pockets weren’t fully cured. Another common cause is that the timber may not have been fully kiln dried. While air-drying is often used in outdoor timber projects, it doesn’t remove moisture and resin as effectively or evenly as kiln drying does. Kiln drying not only lowers the moisture content to a stable level but also helps to “set” the sap, making it less likely to seep out later.

Heat exposure can also be a trigger. When timber steps are exposed to warm weather or direct sunlight—particularly if they face north or west—the heat can soften any resin still trapped inside the wood, causing it to ooze out. This can happen even with well-seasoned timber, especially if it wasn’t sealed or finished properly. Additionally, the way the timber was stored before installation can make a difference. If it was stacked too tightly, covered in plastic, or kept in a damp environment, it may not have dried evenly throughout, allowing pockets of resin to remain that later emerge as sap.

To manage the sap that’s appearing on the surface, start by gently scraping off any visible residue with a plastic scraper. Avoid metal tools, as they can damage the wood surface. Once scraped, clean the area with mineral turps or methylated spirits to remove any sticky film. For stubborn sap, you can apply gentle heat using a heat gun on a low setting or a hair dryer. This draws out any remaining resin, which can then be scraped and cleaned again.

To prevent further sap bleed, it’s essential to seal the timber using a shellac-based primer such as Zinsser B-I-N. This type of product is specifically designed to block resin and tannin bleed, making it a reliable base coat. After sealing, you can go ahead with your chosen topcoat, stain, or exterior timber oil. Keep in mind that resinous timbers, especially treated pine, may still ooze sap occasionally in hot weather, but sealing them properly will greatly reduce the occurrence and protect the finish.

If you have any other questions we can help with, please let us know.

Eric

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