What is 'wood bleed' and how can I fix or prevent it?

Wood bleed has affected almost every experienced painter more than once in their careers. It presents itself as that orange or brown streaky effect that comes through shortly after painting or sealing, in certain cases it may take even longer depending on the age of the item, the cause of the bleed and how the piece was cleaned or prepped. 

It is also known that bleeding occurs mainly within older pieces that are repainted with water based products. In some cases the bleeding only appears after sealing or waxing.

This article will explain the cause, how to avoid it and how to fix it when it happens.

(pic courtesy of SalvagedInspirations.com)

pic courtesy of salvagedinspirations.com

What causes 'bleeding'?

1. Tannins

Tannins are the collective name for the acidic chemicals held within the sap of the wood. These are left behind as the water evaporates once the water evaporates after the wood has been cut. The name comes from the leather tanning industry which used oak, and it's bark to tan leather. It also happens to be the oaky flavour you get from maturing wine in oak barrels.

Different woods have different colour tannins, pine is yellow, imbuia gives off a brown, other woods create and orange. 

You'll find that even after cleaning well with sugar-soap, in certain cases bleeding may still occur, since you have only managed to clean off the first few mm of the wood, but tannins occur throughout the wood, so bleeding may present itself at a later stage.

 

2. Oil, polishes, stains

Most older items have been treated and preserved with various furniture oils. teak oil in particular is a common furniture preserver and does a great job of penetrating through the wood. Cleaning solvents such as Mr.Min are also popular and create their own set of challenges. Some items have been stained with heavy oil-based stains used to darken the wood.

These will pose similar and even more extreme bleeding than natural tannins.

In this example, 30 odd year old wooden doors were painted and sealed, soon after bleeding presented itself. The wood had been treated for years with teak and linseed oil.

 

3. Prevention

The golden rule is to always clean these items well, use sugar-soap and make sure the piece is well cleaned. If the item has been waxed; use methylated spirits or medical alcohol and a rag and strip the wax first and then clean the item. If it's previously been varnished, it must cases the advice is not to sand, unless the varnish is highly solvent and reacts with the water-based product, causing non-adhesion or paint peeling. In the case of high-gloss or veneered surfaces, simply de-gloss the surface using an abrasion pad of light-grit sandpaper.

If the item has an oil-based varnish or paint, use Zinnser 123 Stain block. Follow the directions on the product.

The alternative is Armour, this is Granny B's polyurethane water-based tough-coat sealer. Cover your item in two coats of Armour, allow a curing time of 72 hours. Paint with your Granny B's Old Fashioned Paints and allow the final coat to cure for at least 8 hours. After which you can seal with your Armour again.

The above steps will address 95% of the bleeding cases, but it must be noted that each case is different, and some cases may be impacted by multiple elements at once such as the tannin, having been oiled, stained and waxed.

 

4. The cure

So...you've painted your  item, it looks great until you seal...almost moments later it shows up with brown, yellow or even orange streaks...yip it's bleeding. First thing to remember....it is NOT THE PAINT, it's NOT THE SEALER. Sometimes the sealer seems to cause this reaction, but it's not the case, the sealer is usually a highly water-based deep-penetrating liquid, which passed through the spaces in between the paint molecules, and allows the underlying tanning or stain to 'float' to the surface.

At this point don't panic. Let the sealer dry, apply two coats of Granny B's Armour, and let this cure for 72 hours. Once cured, paint with Granny B's Old Fashioned Paints, and allow the final coat to cure for at least 8 hours before sealing as normal again.

Even this potentially troublesome kitchen  was beautifully painted (by Marlize Greyvenstein) using Granny B's Old Fashioned Paint products, and applying the method of sealing first.

All products are available at www.grannyb.co.za

for more product support info, join our Facebook Group:

Granny B's Painting Studio

email: hello@grannyb.co.za

Tel: 011 7080139

 



Leave a comment