How to Do Chemical Treatment of Wood?

For a long time, people have been using wood in house construction work, manufacturing furniture, and daily life. This natural ingredient is sensitive to moisture and other external factors, which can cause fungi, bacteria, and insects, especially termites, borers to nest and rot. So, for a long-time use of wood, proper protection and preservation of it from harmful effects is very important and essential.

It is very crucial for us to treat the wood before making doors, door frames, and furniture with it. The processing enables the wood to gain resistant power against all kinds of pests including fungi, termites. In this way, we are able to use low-priced wood to make doors, door frames, and furniture with a guarantee and sell it.

Generally, there are 2 types of chemical treatment of wood, namely, i) Modern System, and ii) Traditional or Immersion System

1. Modern System:

By placing the wood in a fixed enclosed container, the vessel is first ventilated by a pump to expel the streaks and air inside the wood or bamboo. Then another pump is run and the mixture of pre-dissolved chemicals is inserted into the container under high pressure so that the solution of the chemical can penetrate deep into the wood. Leaving this condition for 3-4 hours, the solution is pumped out. At once, wood can be treated from 50 to 600 CFT depending on the size of the pot. For example, if a treatment plant of 50 CFT capacity can be operated 4 times a day, 200 CFT of wood can be treated in one day. Several large and reputed doors and furniture manufacturers in Bangladesh like Dream Furniture BD treat or process their wood in this system.

2. Traditional or Immersion System:

In this case, no external pressure or closed vessel is required. The chemical solution is placed in any conveniently prepared tub and the wood is dipped into it. It should be noted that after placing the wood in the basin, the preservative solution should be at least 06 inches above the wood. The wood is soaked in the preservative solution for 01-03 days as required and then dried and used.

Here I would like to mention that since no pressure is applied in this traditional method, chemicals cannot reach the depths of the wood. Chemicals can reach depths up to a maximum of 2-3 mm. Therefore, if the wood is not mature & ripe, even if the treatment is done in this way, there is a possibility of insects getting inside the wood and destroying it.

Almost the same chemical solutions are used in both modern and traditional systems, and they can be used many times in the same solution through quality control subject to testing.

Chemicals used in solutions are noted below.

Borax: Also known as sodium borate. It fights against wood bugs, wood bugs are insects that devour and destroy wood. It is also used in all types of wooden furniture, door-frames, boat preservation and maintenance.

Boric acid: It is an essential substance in the fight against wood insects.

Copper sulphate: Copper sulphate [CuSO4] is a toxic substance. So it is used as a pesticide to protect wood from insects and spiders. It is also used to preserve skin and flowers.

Sodium dichromate: Sodium dichromate is an inorganic compound whose chemical symbol is Na2Cr2O7. Sodium dichromate and potassium dichromate look almost identical. Even the reactivity between them is very similar. However, sodium salt is about twenty times more soluble in water than potassium salt.

Boric acid, sodium dichromate and copper sulphate in a ratio of 1: 2: 2 are used to preserve bamboo or wood. It’s also noted that the mixture of chemicals we use for wood treatment varies.

For instance: When it comes to doors, door frames or furniture used indoors, we use one type of mixture of chemicals, whereas in sphere of doors, door frames or furniture used outside the house, we utilize another type of mixture.

The following is a mixture of 100 liters (borax, boric acid and water) solution to treat wood used for making indoor doors, door frames or furniture:

For 10% density: Borax - 05 kg, Boric acid - 05 kg and water 90 liters (Total: 100 liters )

For 20% density: borax - 10 kg, boric acid - 10 kg and water 60 liters (Total: 100 liters)

Again, a mixture of 100 liters (copper sulphate, sodium dichromate, boric acid and water) solution for wood treatment used for making outdoor doors, door frames or furniture is mentioned below.

For 10% density: Copper sulphate - 04 kg, sodium dichromate - 04 kg, boric acid - 02 kg and water 90 liters (total: 100 liters)

For 20% density: Copper sulphate - 06 kg, sodium dichromate - 06 kg, boric acid - 04 kg and water 60 liters ( total : 100 liters)

However, in our country 10% density solution is very popular, and door, door frame & furniture manufacturing companies are using this solution for chemical treatment of wood.