Tuesday, 1 August 2017

How to Stain Wood

Wood by itself is a thing of beauty. But in many situations, we need to dress up wood to meet the aesthetic and practical requirements of its design and environment of use. Staining wood is the first step in dressing it up. Make pine look like teak wood or wood look like green bamboo, there are innovative ways to achieve striking results.

There are many schools of practice on how to stain wood. Let us look at some traditional and modern methods each have their own pros n cons.

Traditionally in India, wood is stained using powder pigments. These powder pigments are often chalk powder based and it involves mixing of raw pigments such raw sienna, burnt sienna, burnt umber etc with porbander chalk powder. These are then mixed with dispensing media such as French polish, sanding sealers or solvents such as methylated spirit and applied on the wood using a cotton rag. This method hides most imperfections on the wood and is suitable to any type and colour of wood. Unfortunately, along with hiding the imperfections, it also hides the natural grain of the wood giving it a pasty appearance. This method is suitable only for hand polishing or French polish. The stain thus obtained cannot be coated over by melamine or PU as the solvents used to dispense the pigment are not compatible with these polymer coatings. More over, if coated over, the solvents used to stain the wood begin to evaporate and cause the polymer film to break and eventually peel off.

There is another method to stain wood using powder pigments that does not involve solvents. Pure pigments such as the oxides of iron available in yellow, red and black hues can be mixed with water and applied to stain the wood. The intensity of the stains thus created can be controlled by changing the dilution of the pigment. In such a method, a pre stain coating is recommended as the stain can turn out patchy when applied using a rag or a roller. Application of the water based stain thus created causes the wood grain to get slightly raised lending a rough surface. Pre wetting and sanding of the raised grain is recommended to avoid this problem. This method is compatible with all types of wood coatings. Due to the absence of heavy powder usage, the wood grain appears enhanced and clear. The only drawback to this method is control of the stain intensity. Different batches of the stain may turn out different if the proportions are not the same.

The method recommended by most experienced wood workers is staining using manufactured wood stains. These stains are available off the shelf in a variety of colours. They are available in water

based and solvent based varieties. The solvent based variety carries a fast evaporating solvent which flashes off in about 2-3 hours and is compatible with all types of wood coatings. The water based variety dries off slower but provides a more even finish. The water based stain also needs to be applied after pre wetting and sanding for a smooth finish. Both stains can be applied as is or after dilution with an appropriate solvent. To get an even stain, it is recommended to apply a coat of pre-stain before staining the wood.

Application of Stains

The first step to applying wood stain is applying the pre-stain.

What is pre-stain?
Pre stain is a coating used before staining of wood. It partially closes the grain of the wood and makes it less absorbent. The stain applied after pre stain spreads more evenly.

Is pre-stain available in India?
Pre-stain is not available readily off the shelf in India, but one can easily create a pre-stain using the following method:
Purchase a can of the appropriate sealer - it can be water based or solvent based. Some varieties of sealer are: Water based PU sealer, solvent based PU sealer, Melamine sealer, and for hand polish -
sanding sealer.
Thin it 100% using the appropriate solvent. For water based sealers, use water and for solvent based sealers such as PU Sealers, use PU thinner.
This is your pre-stain.
Apply it along the grains using a cotton rag or a roller.
After the application of the pre-stain, the wood stain can be applied using a clean cotton rag or a roller along the grains. More than one coat of stain can be applied to get a greater colour depth, but remember, more stain means lesser natural wood grain.
This completes the wood stain.

To complete the wood finish, wood sealer must be applied over the stain first. Never sand the wood stain. Sanding must be done only after application of the sealer. The sealer now applied must be applied as a sealer coat and not as a pre-stain i.e. the sealer must now be thicker in consistency and used with the intention of sealing the wood completely. More than one coat of sealer must be applied, sanding with emery grit 180 between coats and with emery grit 320 on the final coat. The wood can then be finished using the top coat.

Hope this helps you stain your wood to perfection.

For a huge range of wood stains and sealers, visit http://paintnhardware.com/20-wood-finishes

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