Bleached poplar veneer
- Alkali treatment
Pretreatment with alkali liquor is the first stage of veneer bleaching process, which mainly plays the following roles: First, it can purify veneer and eliminate stain and stain on wood surface; Secondly, a considerable part of resin and soluble colored substances in wood can be extracted in alkaline solution, which is conducive to reducing the consumption of bleach in the main bleaching process; Third, increase the permeability of monopoles by swelling cellulose and hemicellulose. The concentration of lye can be determined by the degree of dirt on the veneer surface and the level of wood content.
- Wash and filter dry
During alkali treatment, other impurities such as resin and organic acid dissolved in alkali liquor shall be washed away repeatedly with a large amount of clean water, which can not only save bleaching agent, but also prevent the ineffective decomposition of hydrogen peroxide caused by some impurities on the veneer surface. 3. Main drift
The main bleaching is the most important stage in the veneer bleaching process. In this stage, through the oxidation of hydrogen peroxide, the conjugated double bonds on the side chains of lignin are broken, the chromophore group breaks, and the absorption spectrum moves to the ultraviolet light region, leading to the whitening or lightening of the veneer color, so as to achieve the purpose of veneer bleaching.
- Post processing
The bleached veneer still contains unreacted hydrogen peroxide, other lyes and additives, which affect the normal dyeing of the veneer. Therefore, a large amount of clean water must be used to thoroughly clean the veneer to neutral and then filter it dry.
- Drying
For the convenience of use, the bleached poplar veneer needs to be pasted with tape to prevent cracking and dried. The moisture content is generally controlled within 16% according to the use situation
