WOOD FINISHES AND CLEANERS/STRIPPERS

WOOD FINISHES

Natural (Clear)
Transparent (Toners, Tones)
Semi-Transparent     

In simple terms, oil based finishes seek to replenish the natural oils the wood has lost due to the harvesting and processing of the timber. They also help breathe new life into old weathered wood.

NATURAL (CLEAR) oil based finishes contain various types of synthetic and/or natural oils to protect and nourish the wood fibers.  However, natural (clear) finishes contain little or no pigments that help protect the wood from ultraviolet rays of the sun. Without this protection, the wood will soon succumb to ultraviolet degradation and begin to deteriorate (turn gray).

TRANSPARENT (TONERS, TONES) oil based finishes offer the protectant oils that the natural (clear) oils offer with the addition of pigments for protection from ultraviolet degradation. Toners contain fifty percent less pigments than the semi-transparents.  Toners (tones) maintain the look of new or freshly cleaned wood.

SEMI-TRANSPARENT oil based finishes offer the protectant oils that the transparent (toners, tones) oils offer with the addition of approximately fifty percent more pigments for protection from ultraviolet degradation.  The most common type of pigments are Transparent Iron Oxide Pigments. The finish life of the semi-transparents is substantially longer than the toners (tones).

TRANSPARENT IRON OXIDES (TRANSOXIDES): The ultraviolet component of sunlight is principally responsible for the degradation of wood.  Transoxides are strong absorbers of ultraviolet radiation providing protection for the wood while their color and transparency enhance the appearance of the natural wood grain.  The high durability and weather fastness of transoxides make them the natural choice for wood finishes.

Transoxides enrich the colors, increase color shades when combined with organic pigments and improve the condition of poor weather fastness when pigments and dyes are used alone without Transoxides.

SOLID OIL BASED FINISHES:

Solid oil based finishes are useful in the case of a wood surface that is degradated to a point where a semi-transparent finish will not camouflage the damage efficiently.  They offer similar protection as semi-transparent finishes; however, they mask the beauty of the natural wood grain.

WATER BASED FINISHES:

These finishes can be a problem when applied to a horizontal surface, such as a deck floor.  The problem arises when the wood structure expands and contracts with exposure to moisture and temperature variations.  The water based finish, which forms a solid film, cannot expand and contract with the wood structure and will typically peel and flake.

The water based finishes normally do not contain oils that help to preserve and protect the wood.

WOOD CLEANERS/STRIPPERS

SODIUM HYDROXIDE:

This is the basic ingredient in almost all strippers for oil based finishes.  However, sodium hydroxide, in and of itself, is not effective as a stripper.  Applied directly to an oil based finish it will not initiate any stripping action until a surfactant is added.  Surfactants are wetting agents that lower the surface tension of a liquid allowing easier spreading.

Sodium hydroxide based strippers can be adjusted to the condition of the finish to be stripped by increasing the sodium hydroxide percentage, adding Butyl, Sodium Metasilicate or other additives.

An important factor involved is the dwell time required for the stripper to perform.  Keep in mind; the increased strength and dwell time for the stripper to work on strong finishes will result in the raising of the grain of the wood.  “The fuzzies” require buffing or sanding.

The sodium hydroxide stripper must be neutralized with an acid because sodium hydroxide is highly alkaline.  Leaving the wood in an alkaline condition will alter the curing process of the finish and result in premature failure.

SODIUM HYPOCHLORITE (BLEACH):

Wood is basically cellulose and lignin, the substance that holds cellulose together.  Bleach erodes the lignin allowing the cellulose, in a sense, to fall apart.

When a wood surface if cleaned with bleach, it is not really clean, although it may look as if it is.  It has only had the color of the stains removed.  What remains is “clean dirt.”

Bleach does, however, have a use in wood restoration.  It is a very good means of killing mold and mildew spores.  If you see any green or black fuzzy areas on the wood after cleaning, spray them with a very mild solution of bleach and water and continue with the neutralization.

SODIUM PERCARBONATE:

This is an excellent and safe chemical for cleaning wood that has almost no finish remaining or no finish that has been degradated by the ultraviolet rays of the sun and turned gray.

Sodium percarbonate can also be used in a very weak form to clean wood prior to a maintenance coat being applied. 

Mixing sodium percarbonate with water releases hydrogen peroxide and soda ash.

Sodium percarbonate must also be neutralized with acid.

METHYLENE CHLORIDE:

Methylene chloride is a very effective chemical ingredient in paint strippers.  The stripper is best applied with airless equipment; however, it may be brushed on the surface.  Dwell times are very important and vary from 15 minutes to several hours.

Following application and dwell time, the residue may be scraped, brushed or rinsed with high pressure.

There are many brands on the market.  Run an Internet search under “Methylene Chloride Paint Strippers.”

TRISODIUM PHOSPHATE (TSP):

In combination with surfactants, TSP is excellent for cleaning everything from laundry to concrete.  This versatility combined with low toxicity and low manufacturing price makes TSP a very popular ingredient in many cleaning products.  TSP is an excellent cleaner for use in cleaning wood for maintenance refinishing.

TSP may also be mixed with a mild bleach solution for mold and mildew removal.

Depending on the strength required, TSP may have to be neutralized.

OXALIC, CITRIC, SULFAMIC AND PHOSPHORIC ACIDS:

The easiest way to explain the differences among these acids is in their strength and ultimate neutralizing effectiveness. 

Citric, sulfamic and phosphoric acids are all used in a variety of home use products and foodstuffs.  Make no mistake, they are still acids and are hazardous.  However, compared to oxalic acid they are much less hazardous.

It follows, therefore, that their neutralizing powers are not as effective as oxalic acid.  An important point to remember is that the stronger the stripper, the stronger the acid has to be to effectively neutralize it.  Oxalic acid is also very effective in removing mill glaze from new wood surfaces.

A good compromise would be Citrolic Acid, a combination of citric acid and oxalic acid.

RINSE, RINSE, RINSE…………When you are certain you have rinsed as much as you can, rinse everything one more time.  The extra couple of minutes it takes you to rinse well is nothing compared to the time it takes to strip and reapply a finish that failed because you did not rise well enough.