During the alkali treatment of plant fiber, the solution may turn black in the first treatment due to the reaction between the alkali (sodium hydroxide) and the plant fibers. This reaction can cause the fibers to break down and release pigment or other substances that may contribute to the color change of the solution.

In the second treatment, the solution may turn light blue due to the formation of a compound called sodium carbonate. This compound can be produced through the reaction of sodium hydroxide with carbon dioxide in the air, which can lead to the light blue color of the solution.

It is important to note that the exact color changes that occur during the alkali treatment of plant fibers can vary depending on the specific plant material being treated, the concentration of the alkali solution, and the conditions of the treatment (such as temperature and duration).

Thank you Suganth Velumani.

Can I get valuable information from the lacquer resulted from the treatments using UV/Vis or any other methods?

Lacquer is a type of coating or finish that is used on a variety of surfaces, including wood, metal, and plastic. It is made from a resin, such as shellac, that is dissolved in a solvent and applied to the surface. Lacquer is known for its high gloss, durability, and resistance to water and other environmental factors.

The properties and characteristics of lacquer can be affected by various factors, including the type of resin used, the solvent used, and the methods of application and curing. UV/Vis (ultraviolet/visible) light or other methods can be used to treat lacquer to change its properties or to enhance its performance.

For example, using UV/Vis light to cure lacquer can speed up the drying and hardening process, and can also improve the durability and resistance of the coating. Other methods, such as heat curing or chemical crosslinking, can also be used to alter the properties of lacquer.

The specific effects of UV/Vis treatment or other methods on the properties of lacquer will depend on the specific formulation of the lacquer and the conditions of the treatment. In general, however, these methods can be used to enhance the performance and durability of lacquer coatings.