Prevention of wood discoloration

Prevention of wood discoloration

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If the surface of the wood has already produced photochromism, sanding or cutting can be used to remove the discoloration.

Floor. If the color changing layer is very light, bleaching can be used to remove the chromophoric compound from the surface, such as

Hydrogen peroxide, sodium chlorite, and the like. Wood that does not produce photochromism can be treated as follows:

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The most used in physical methods is to cover the surface of the wood with a paint or varnish.

Degradation of wood components due to ultraviolet light and visible light only occurs on the surface of the wood, and the thickness is

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Light irradiation prevents the occurrence of free radical degradation reactions. Simultaneously

Infiltration, it can also improve the dimensional stability of wood and reduce the discoloration caused by the removal of wood extract.

Because paints have a wide range of colors to choose from, they are easy to apply and have good results, so people have long been

This method is widely used for furniture and decoration. However, the paint has poor transparency. Can't show perfection

Wood natural texture with color. Although varnish can make up for this defect, varnish is sensitive to water.

Strong, the film is brittle, easy to fall off, and has a short service life. No paint or varnish has anti-corrosion effect.

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1 UV absorber. Treating wood surfaces with UV-containing coatings can effectively prevent

Light discoloration. Such as salicylic acid derivatives and

Absorbing wavelength at

2 Change the functional group of the wood component to destroy the structure of the substance involved in discoloration. Due to lignin

a

This structure is an effective method to prevent photochromism. Methylation, acetate, and benzene are commonly used in wood.

A combination of acylation and oxidation or reduction, destroying the chromophores of wood and the precursors that cause discoloration

The material structure prevents the photodegradation of wood and the effect is very good. If the wood is treated with diazomethane,

The carbonyl group is converted to ethylene oxide to increase its stability. These treatments also apply to wood caused by extracts

The material is discolored. Can change the aromatic ring side chain. The chemical reagents of a carbonyl structure mainly include: diazomethane, sulfur

acid

Acyl and the like. Polyethyl

Photochromism, but the effect on wood with darker wood is poor.

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a peroxide that destroys the structure of the chromonic material and whitens the color of the wood, thereby inhibiting

The color of wood is discolored. In addition, chemical agents and preservatives that prevent discoloration of wood are also commonly used.

The agent and the dyeing agent are used together to improve the ultraviolet rays during the process of dyeing, anticorrosion and waterproof treatment.

The ability to block absorption. Some reagents with oxidation and complexation (such as chromium trioxide, copper chromate).

Semi-carbonitrile and its derivatives) and stabilizing metal salts (such as magnesium or alkaline earth metal sulphur)

Acidic acid, thiosulfate, and reduced compounds such as ascorbic acid) can be used to coat wood surfaces.

Prevent the initial discoloration of wood. These chemicals can be complexed or oxidized by chemical components of wood.

The role prevents the degradation reaction from occurring. It also improves the durability of coatings and colorants, while some reagents are also

Has antibacterial ability.

3 wood staining. In order to prevent the fading and discoloration of wood, some woods need to be used before they are used.

Dye coloring or coloring. Dyes can be divided into acid dyes, basic dyes, direct dyes and oils.

dye. Acid dyes are used more. Acid dyes dye lignin, not cellulose and

Hemicellulose staining. This effectively prevents lignin browning caused by photochemical degradation. dye

The color can be selected from the colors of some precious wood, such as mahogany, rosewood, ebony and so on. For staining

Evenly, the wood is generally pretreated with a dilute alkali solution (

Again

wood. In the wood dyeing process, the dye can be impregnated to a certain depth of wood, but does not form an independent

The coating can produce polar adsorption, hydrogen bonding or chemical reaction with components in the wood. therefore,

In use, sunlight, wind erosion or excessive moisture does not cause foaming or flaking on the surface of the dyed wood.

Therefore, the dyed wood is stable in color, has less degradation reaction, and is durable in materials. But because of wood

The structure of the tissue is densely arranged, so that the dye molecules are not easily penetrated into the depth of the wood. Under normal pressure, generally only

Shallow dyeing, re-processing color is not easy to retain. With pressurized treatment, it can only be used for difficult-to-penetrate materials.

Handle smaller components. The use of standing wood dyeing and veneer dyeing can make the colored layer deeper or evener.

But consider the effect of dyeing on gluing and finishing.

2

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The part. For smaller areas of discoloration, it can be removed by planing or sanding; for large area changes

1 first brush it again

Amount

2 use

g

3 use

4 use

5 use

5 in

It can prevent iron pollution.

1 Put the disodium salt of oxalic acid, ammonium dihydrogen phosphate and ethylenediaminetetraacetic acid into the pool of steamed logs

It can prevent iron pollution.

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Disodium hydrogen to prevent acid discoloration. For surface discoloration, it can be removed by shaving or sanding.

The method is as follows:

1 at

Applied to a contaminated surface;

3 will

3 will

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The surface of the wood and the surface of the wood treated with a strong alkaline bleach.

Initial alkali contamination can be removed by aqueous shikimic acid solution

The dyeing time is longer. Then change the concentration to

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The anti-blue-modifying compound with excellent performance should have broad-spectrum activity, low toxicity, and easy preparation and use.

Low cost features. There are many factors affecting the properties of anti-blue-induced compounds, including broad-spectrum activity and various killings.

Combination of microbial agents, interaction between fungicides and wood components, tree species, storage after treatment

Condition, the environmental conditions for the use of wood, etc.

For a long time, wood anti-blue coloring agents are mainly sodium pentachlorophenol and sodium tetrachlorophenol. Such drugs for prevention

Microbiological hazards are very effective and are broad-spectrum antibacterial agents. But these more toxic drugs

Agents have many adverse effects on humans and the environment. Therefore, the currently used antiseptic and anti-tarnish agents

Toxicity has increasingly caught the attention of researchers. The use of such agents has been banned in some countries in the United States and Northern Europe. With the advancement of human beings and the deep research of human beings, some preservatives with high toxicity and easy loss will stop.

Use, new and non-toxic high-efficiency preservatives and new anti-corrosion routes are urgently needed. Used in recent years

Some anti-tarnish agents are described as follows:

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Methylthiobenzothiazide thiocyanate

These are the second generation of wood anti-blueing agents after sodium pentachlorophenol and sodium tetrachlorophenol. Its toxicity.

Sodium pentachlorophenolate and sodium tetrachlorophenol. Various forms

Bactericidal effect, such as

The anti-mildew effect is higher than that of sodium tetrachlorophenol. For new substitutes, the effect is sustainable.

Washing and immersing the wood,

Ug/cm2

Non-polluting, non-toxic to humans and animals, non-corrosive to metals, low cost, diffusion of wet wood

Good sex, poor resistance to loss, anti-blue color effect is lower than sodium pentachlorophenol and sodium tetrachlorophenol, and in wood

The enzyme compound chemically reacts to produce browning. Contain

Water forming agent

Shi

MTB

Wood,

The problems in the skin are irritation to the skin and toxicity to fish.

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Season hinge salt

Very effective active ingredient of the agent. It can be formulated into oil-soluble and water-soluble formulations. Oil soluble

The most commonly used preservative for impregnated joinery is the finely divided formula

Butyrate

United States and Japan).

Used in combination with other chemicals for wood preservatives in contact with soil.

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It is an efficient broad-spectrum fungicide and is the most promising wood antiseptic and anti-tarnishing agent. Correct

The village has a natural affinity and can be fixed in wood by cation exchange, but exposed to acidity.

Under the piece (such as acid rain) its effect is significantly reduced. This drug fixation is slower, sometimes up to

Timbercote

In use, it is effective against blue, and it can protect the surface and interior of wood. Anti-blue change, antiseptic

NP

DDA

Variable bacteria have a good effect

Ingredients are

Decay,

F

Degree

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Triterpenoids

A new class of wood resistant to blue and antiseptic agents.

for

1

The amount is

contain

The bubble method and the spray method treat a variety of woods, and the anti-blue color effect is good under various climatic conditions.

AP

of

30WB

Moderately toxic, low to skin irritation and irritating to the eyes.

The active ingredients are triterpenoids and chlorothalonil (

Anti-blue effect, chlorothalonil inhibits mold very effectively, so

The blue and mildew of the newly cut wood and the untreated logs are also inhibited by decay. Follow the United States and

European test methods have shown that Taibu Kangxi has effective defense against basidiomycetes of decaying wood.

The effect of treatment, especially on brown rot fungus and white rot fungus. Tabu Kang has low water

Solubility, high stability to heat and light, and miscibility with other active ingredients. For mammals, fish and algae

It is biotoxic and biodegradable.

5 chlorothalonil (

Chlorothalonil is one of the broad-spectrum fungicides used in recent years. Used in the United States

Toxic, does not cause mutations in mammalian genes. Solubility in water is

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for

Officially listed

Wood mold

Effective chlorothalonil preparation for preventing mold

0

Agent ten

Effective chlorothalonil preparations for color-changing bacteria mainly

Mycelium clearing agent,

NaPCP

Mildew

loose

phenol. Loss tests show that the fixation is superior to pentachlorophenol and is environmentally safe. Chlorothalonil and poisonous monument

Chlorpyrifos

Has good anti-wood rot and anti-termite performance, is

Use will reduce the cost of preservatives.

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*) Thermal discoloration. In order to prevent the drying bow

Chemical tests for sodium, sodium bisulfite, ascorbic acid, semicarbazide, urea, semicarbazone and zinc oxide

These can effectively prevent thermal discoloration. In addition, use organic solvents or hot water to treat wood before discoloration.

material

The color changing layer is removed because the thermal discoloration is almost limited to the surface. Bleaching agent oxidative decomposition method

Remove, such as repeated brushing of the material with alkaline hydrogen peroxide or sodium chlorite solution.

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Or microwave radiation treatment, these can destroy the living conditions of the enzyme and prevent the wood enzyme from discoloring. In addition, in

When dealing with wood, add antioxidants, such as

In the organic solvent, the surface of the wood is also rubbed to inhibit the discoloration of the enzyme.

For wood that has produced enzyme discoloration, it can be bleached or hot water extracted by hydrogen peroxide or the like.

Remove.