FAQ: What Are Tannins In Wood?

Tannins are naturally-occurring compounds found in wood and other plants, including those in coffee, tea and grapes/wine. They help prevent disease and regulate the plant’s growth. Because of their chemical nature, the tannins seep to the surface, even after the wood is completely dried and carefully painted.

How do you remove tannins from wood?

Remove the stains with oxalic acid or an oxalic-based solution. 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.

Which woods are high in tannins?

Oak, walnut, cherry, and mahogany, have higher tannin levels, while maple, birch, and aspen rank low in tannin content and acidity. Unfortunately, both madrone and red alder fall into the high-tannin category. In fact, madrone bark has been used to tan leather.

Are tannins good or bad?

Although largely useful to the body, tannins also have negative effects. They are often anti-nutritional and can hinder digestion and metabolism, unlike polyphenols. Tannins can also help obstruct the blood’s absorption of iron, which may lead to many health problems.

Does all wood have tannins?

Some woods, such as oak and walnut, have naturally occurring high tannin content, which means you can apply the oxidizing solution at this point. Some woods, however, do not have enough tannins to make much of an impact with oxidation.

Will tannins go away?

The first thing you need to know is that this stuff is harmless. It just looks like &*&%$. It typically will go away on its own with minimal intervention on your part, but you could always give it a good scrub with a soft-bristle brush (like an old toothbrush), and a rinse in freshwater.

How do you seal tannins?

Seal the stains with an alkyd/oil primer or a coating designed to trap these tannins. Note: Even with proper preparation and recommended products, tannin bleed can still occur, especially on new wood, with either latex or oil topcoats. To wash off the tannin stain, use SuperDeck® Revive® Deck and Siding Brightener.

Is oak High in tannins?

Immature oak leaves and freshly fallen acorns contain the highest concentrations of condensed and hydrolyzable tannins. Condensed tannins are resistant to hydrolysis and tend to pass through the GI tract unchanged without causing significant disease problems.

Is teak high in tannins?

Hard and fairly dense, teak has been used for centuries in furniture making. It is known for its uniform dark brown colour and straight grain but does have high oil and tannin levels.

Does mahogany contain tannins?

Generally speaking, however, lighter-colored woods like maple, birch, and aspen contain less tannic acid, while darker-colored woods like oak, cherry, mahogany, and walnut contain more. Higher levels of tannic acid can cause discoloration in the staining and/or coating processes.

What is the benefit of tannin wood?

Tannins are found commonly in the bark of trees, wood, leaves, buds, stems, fruits, seeds, roots, and plant galls. In all of these plant structures, tannins help to protect the individual plant species. Tannins that become stored in the bark of trees protect the tree from being infected by bacteria or fungi.

What are the side effects of tannins?

The FDA has asked for more studies. In large amounts, tannic acid can cause side effects such as stomach irritation, nausea, vomiting, and liver damage. Regular consumption of herbs with high tannin concentrations seems to be associated with an increased chance of developing nose or throat cancer.

How much is too much tannins?

As with everything, tannins should be taken in moderation. No more than 2 daily cups of tea that are very tannic (like black tea), and you’ll be alright.

Does Douglas fir have tannins?

Timber from the Douglas fir is used in home construction, telephone poles, bridges, millwork, fences, barrels, plywood, chipboard, and kraft paper pulp. The wood is moderately acidic containing some organic acids. The bark contains catechol type tannins that are used to produce pliable, light-color leathers.

Does pine contain tannin?

Bark of Norway spruce and Scots pine trees contain large amounts of condensed tannins. Tannins extracted with hot water could be used in different applications as they possess antioxidative and antimicrobial activities.

Is Douglas fir high tannin?

SPECIES Mid-high tannin woods like cedar, redwood, douglas fir, maple, alder, hickory, locust, walnut, oak, etc.