" " wisno wood furniture finishing: Water-based coating for furniture finishing

Saturday, October 24, 2009

Water-based coating for furniture finishing

Waterbased coating could be the answer from the finishing material industry to provide the material that is environmental friendly. Water based coating is the finishing material that is purposed to provide the environmentally friendly and safe for the finishing process. Water-based coating uses water as its major thinner. It releases water at the application and the drying process which is more safe and environmentally friendly than any solvent. The modern finishing process will always "give" pollutant to the air and environment. All the solvent that used in finishing process will evaporate in a fume to contaminate the air and environment. The gas fuming is released during the application and drying of the finishing materials. The spray process which is very popular in the finishing industry always produces dust sprays that leave to the air and the environment. 

Now when the peoples more consider about the safe and healthy environment, the finishing process especially in the developed countries must be done with a very strict rule according to the cleaning and environment aspect. Thinner and finishing materials are also consider as very flammable materials, so finishing process also requires a tight safety rules to prevent fires. The gas released is restricted in many country, and it attract people to use the water-based coating.

Water-based coating usually is made of acrylic resin, modified acrylic or “one component polyurethane”. These materials actually are not soluble in water, so the resin mixture is dissolved in a solvent that evaporates slower than water. In the drying process, the water as the major thinner is evaporating before the solvent. After most of its water evaporated then the paint solution will release his solvent to make a dry film layer.

Into the water-based coating is added a surfactant to make the mixture disperse into the water and form a homogeneous emulsion. Surfactant used is a kind of soap and often creates bubbles during application. Defoamer is added to reduce the bubbles was. To the mixture of materials are also added some other additives to obtain specific properties desired. The resulting film layer is termosetting layer that can not be dissolved again by the water, or solvent. This film layer is relatively stronger compared with nitrocellulose coating, but still less strong then  the acid curing or polyurethane coating.

The advantages of water-base coating
  • Non-flammable and produces less air pollution.
Water-based coating actually does not mean not using a solvent at all, Water-based coating also uses solvent, but in a small amount because his major thinner is water. Since that the finishing process with water-based coating is much more secure than the solvent base coating. Water-based finishing is also more environmentally friendly than solvent base paint. Now when the environmental is a very important issue, then the uses of water-based coating is very interesting.
  •   The resulting film coating is strong
The film produced by water-based coating is a termosetting film that will resistant to solvent and scratches. This film layer is stronger than the coating film produced by nitrocellulose coating, but less strength than the acid curing or polyurethane clear coating.

The disadvantages of water-based coating
  • The resulting appearance is slightly cloudy. 
The drying of this coating is with the chemical reaction. The reaction will affect the clarity of the final film result. For high end furniture products that need the beauty and clarity of his finishing look, this coating cannot produce the look as the solvent base material.
  • The application is relatively difficult
The paints use water as its main thinner, while the water is more difficult to evaporate compare with solvent. Therefore, the water-based coating needs longer time to dry, compared to solvent base coating. This coating is also more sensitive to environmental conditions, especially the temperature and humidity of the air. When the environment air is dry and hot, this coating can dry quickly, but at a cold temperature and high humidity air, the paint will be difficult to release his water into the air. Therefore an oven is recommended facility in the finishing room for water based coating. The oven could help to the finishing process by control the air temperature and humidity. Another problem in the handling of water based coating is the equipment and tools that used to process and storage this material. Water is more corrosive material compared with solvent, so the tanks and equipment used for storage and applications should made of plastic or stainless steel which is more resistant to water corrosion.

1 comment:

  1. I recently took a course that featured a focus on the industrial applications of polymers/industrial chemicals with a portion dedicated to thin films/coating/plating that lamentably mentioned nothing about water transfer printing reverse osmosis system