SELECTING
& PURCHASING
Specialty
Finishes for Hardwood Floors
Bleaching,
pickling and antiquing are popular treatments for hardwoods throughout
the home. Choose pre-finished flooring if you want these specialty
finishes: they are not recommended for do-it-yourselfers. Bleaching
-- which is the first step in pickling or antiquing -- can weaken
the wood and affect its ability to withstand every day wear.
Bleaching,
Antiquing, Pickling and Coloring
Surface Preparation
Bleaching and other finishing techniques require an absolutely
smooth work surface. Before beginning any finishing procedure,
check the wood for defects, such as dents, scratches and stains,
then sand the surface until smooth, with increasingly finer grits
of paper. Clean the wood with a soft brush or tack rag and check
the surface again under good light for scratches or blemishes.
Bleaching
Most hardwood species can be bleached to complement a decorative
motif, but darker hardwoods like red oak, hickory and ash are
particularly suited for this application. Bleached, antiqued,
pickled and colored hardwoods are preferred for decorative applications
like mouldings, mantels, paneling, chair rails and decorative
millwork. Experts recommend that you avoid bleaching hardwood
floors, however. This process often weakens wood fibers, making
floors more susceptible to the wear of regular foot traffic (For
more information, see Quick Tips below).
The preferred method for bleaching hardwoods is a two-step process:
1. Brushing the wood with caustic soda or ammonia; and
2. Applying hydrogen peroxide.
In the first step, apply the caustic soda solution with a synthetic
brush, evenly and liberally in the direction of the grain. Let
the solution set for 10-20 minutes. The longer the set time, the
whiter your wood will be. Do NOT let the caustic soda set for
more than 20 minutes, however, because it will cause uneven bleaching.
Next, use a clean synthetic brush to apply the hydrogen peroxide.
A foaming action will take place as the two solutions react. This
is the actual bleaching process, and usually takes 30 minutes
to an hour to complete. If the wood is not white enough apply
the hydrogen peroxide again.
When the wood is sufficiently bleached, wash it down with clean
running water, using a brush to supplement chemical removal. Dry
the hardwood with paper towels and repeat the rinsing process
again in 20 minutes. Rinse out all traces of the bleach or you'll
experience problems when finishing. Let the wood dry in a well-ventilated
area for at least 24 hours. Do not dry the material in direct
sunlight, since this will intensify the bleaching process and
lead to uneven coloring.
Preparing Bleached Woods for Finishing
Bleaching causes the wood grain to rise. Smooth the surface again
with a 180 grit sandpaper, and wipe away the sanding residue.
Now the wood is ready for sealing (if you plan to leave it bleached),
or for antiquing, pickling or coloring.
Antiquing, Pickling and Coloring Hardwoods
Antiquing makes hardwood look "aged" by distressing the edges,
cracks and crevices of the wood.
Before antiquing, seal the surface with a thin coat of white shellac.
This will protect the bleached shade of the wood, allowing you
to work with the glaze until you've achieved the proper look.
Allow the shellac to dry for two hours then lightly sand the surface.
Prepare the antique glaze to the desired shade and apply it evenly
one section at a time. Use a clean rag to wipe off excess glaze.
Remove glaze from sections that experience greater wear to simulate
a "worn-in" (or "distressed") look. Glaze more heavily at normally
protected edges and crevices which don't see as much wear and
tear. Use a clean, dry brush to spread the glaze, removing noticeable
edges produced by your cloth. With the brush, work the color from
the light center to the darker edges, producing a feathered effect.
Allow the glaze to dry overnight. Lightly sand, clean and apply
a coat of shellac. Conclude with the Finishing procedure described
below.
Pickling highlights the pores and crevices of wood by adding a
stain that contrasts with the bleached finish. Start by sponging
the application surface with clean water. Allow the water to dry,
then lightly sand the surface with a 150 grit paper to smooth
the raised grain. Evenly apply a light oil stain, and wipe off
the excess with a cloth. Let this dry for 12 hours. Pickling will
take full effect as the stain adheres to the lightly raised wood
grains. Seal the stained surface with a thin coat of a non-yellowing
polyurethane, and complete by Finishing as described below.
Coloring involves applying varying degrees of pigmented stains
to lighter-hued hardwoods to highlight the grain of the wood and
add color.
Oil-based stains and aniline dyes are most popular because of
their workability, but a variety of stains and coloring mixtures
are available today. Select a color and follow the manufacturer's
instructions. Sand, clean and apply the stain with the grain of
the wood. You can achieve deeper shades by applying multiple coats.
When dry, follow the Finishing process.
Finishing
Make sure the wood is clean and dry, then brush on a top coat
of polyurethane, lacquers, shellac or water-based sealers. These
popular finishes come in three sheens: gloss, semi-gloss and satin.
Finish the entire wood surface, not just visible areas, and allow
it to dry overnight. Apply a second coat of finish in the same
manner. Repeat sanding of the woodwork, applying multiple coats
until the wood achieves the desired luster.
QuickTips
Bleaching Kits
Some commercial hardwood bleaching mixes differ from the two-step
process described above. Always follow the manufacturer's instructions.
White Oak
White oak is not recommended for bleaching applications because
it has a tendency to discolor.
Sanding
When doing multiple sanding and finishing cycles, do not re-sand
the wood until it is completely dry.
Use a 220 grit sandpaper instead of steel wool when sanding water-based
finishes because undetected steel fibers can cause rust marks.
Expansion/Contraction
One effect of bleaching hardwoods is that normal expansion and
contraction may expose darker, untreated shades of wood in the
cracks between joints. These gaps occur in all hardwoods, but
are more obvious in chemically-lightened woods.
Use Pre-Finished Flooring
Most professionals avoid bleaching hardwood floors because the
process may weaken the wood. However, many flooring companies
offer pre-finished hardwoods in bleached, pickled and other specialty
finishes.
Samples
Before starting any bleaching or staining project, practice on
a piece of scrap wood of the same species to make sure the sample
meets your expectations.
Work-Site Conditions
Protecting unfinished hardwood from moisture and fluctuations
in temperature and humidity is vital, especially for the extended
drying periods associated with bleached hardwoods.
For more information on proper worksite care, see Tips & Techniques
#1: Installing Hardwood Floors Over Concrete Slabs, and Tips &
Techniques #3: Hardwood Flooring and Millwork Finishing Options:
Pre-Finished or Site-Finished?
Health and Safety Precautions
Most stains and finishing chemicals, especially bleach, are poisonous,
flammable and corrosive. As a result, you should always:
- Wear protective
overalls and gloves.
- Wear a
mask to protect against dust when sanding, and toxic fumes when
finishing.
- Stain
in a dust-free and well-ventilated work area.
- Keep a
bucket of clean water and a sponge nearby in case your skin
is exposed to bleach or caustic stains.
- Clearly
mark left-over materials if they aren't in their original container.
Keep all stains and finishing materials in a cool, dark environment,
away from children and pets.
- Follow
the proper environmental guidelines when disposing of toxic
and/or hazardous chemicals (which includes most hardwood stains).
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