The problem of Tannin bleed

A customer recently contacted us for advice on how to prevent a classic problem that haunts every painter of new garden cabins: tannin bleed.
We helped our customer navigate this issue, and the results speak for themselves. Here’s a look at the problem and the solution he used with our specialist BEDEC products

Understanding Tannin Bleed

The frequently encountered problem with some water-based paints applied to timber is stubborn yellow or brown staining, known as tannin bleed.
• What is it? Wood naturally contains water-soluble extractives, including tannins (polyphenols).
• How does staining occur? When a standard water-based paint or primer is applied, the water conveys water-soluble extractives to the surface causing unsightly stains to bleed right through the fresh topcoat.
• Which woods are worst? This is especially true of, resinous hard woods like oak, and some softwoods like cedar. (Check our Wood Guide for more information on which species require extra care.)

Another Hidden Threat is Rust Staining
Beyond tannins, new wood structures often face another painting challenge: rust marks. These appear when moisture interacts with nails or metal fixings, drawing rust stains to the surface and spoiling the final finish.

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The BEDEC Solution: Two Simple Steps

To ensure a flawless, long-lasting finish, we advised our customer to use a specialized primer and professional top coat.

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Step 1: Stain Blocking Primer – BEDEC ALL PRIME®

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To lock down the tannins we recommended starting with BEDEC ALL PRIME®.
This revolutionary product is a Water-Based, Multi-Surface, Bond Coat Primer that offers three essential benefits in one coat:
1. Stain Blocker: It effectively seals the tannins within the wood, preventing them from bleeding through the topcoat.
2. Rust Inhibitor: It actively works to stop rust marks from metal fastenings being drawn to the surface.
3. Superior Adhesion: It provides an excellent bond coat ready for almost any decorative topcoat.

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Step 2: The Topcoat – BEDEC AQUA ADVANCED

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Once the primer was dry, the next step was to select a suitable, high-performance topcoat. The customer had various BEDEC options. He could have used our Barn Paint or MSP but decided to use Aqua advanced.
The Aqua Advanced range is a professional trim paint that uses a clever blend of traditional and polyurethane resins to create a highly durable and hard-wearing surface.
• Key Feature: Its excellent flow and levelling properties make achieving a smooth, professional finish straightforward.
• Versatility: It is suitable for almost any substrate, making it a perfect choice for interior and exterior wood and trim.
• Finish: It’s available in four levels of sheen: Gloss, Satin, Eggshell, and Matt.
We always advise at least two coats of AQUA ADVANCED top coat for the best coverage, and light sanding (denibbing) between coats can often help achieve that factory-smooth finish.
Aqua advanced is designed as a three-coat system of Aqua advanced primer undercoat followed by two topcoats of Aqua advanced however in this case the aqua advanced undercoat was replaced with BEDEC ALL PRIME due to the possibility of staining.

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