" " wisno wood furniture finishing: Crater in the wood finishing

Monday, October 25, 2010

Crater in the wood finishing

crater in the wood finishing

Crater problem.

Crater or fish eye is a serious finishing problem and quite difficult to be handled. Crater is the existence of holes like caldera arising in the finishing layer. This problem has a very distinctive appearance with the visible presence of a finish layer that does not blend with the surface of the substrate. The finishing that is got crater is need to be striped off and refinish with the right way.
Crater was due to the contamination of finishing materials in the application. The contaminants are chemicals that do not compatible with the finishing material, usually oil or silicone. This contamination can occur during finishing materials are stored, mixed, and used. The contamination can also happen in the application when the contaminants are mixed with air compressed in the piping, or be attached to the wood surface, or it could be in the air in the finishing room. 

How to solve the crater problem.

Crater actually is can be easily solved by preventing the contamination in the finishing process. The most difficult part in overcome this problem is to know  the source of the contamination and when the contamination is happen. There are many possibilities that could cause the contamination and sometimes need lot of time for observation to solve this problem.
Here are the things that can be done to solve the crater in a finishing process:
  •  Clean the finishing room.
The air from the environment is one thing that should be highly suspected as the source of the contamination problem. Silicon could be floating around in the air and then fell and mixed with finishing material or attached to the surface during the process of finishing. Therefore, if crater problem is occurred, first time we need to do is to clean the room and  its environment air. Close the finishing room so it is isolated from the outside environment air that may caused the contamination.
  • Clean the surface to be finished.
Contamination can also occur on the surface of wood or substrate since of various reasons. Therefore, before the finishing process is done, check carefully to the unfinished surface. Wipe the surface with a cloth soaked in thinner before the application of finishing materials.
  • Clean the compress air line.
The contaminants could also arise from the compressed air line. The compressor could leak making the lubricating oil mixed with the compressed air. Lubricants for compressor sometimes are incompatible with the finishing material and ultimately causing crater problem. Periodically checking to the condition of the compressor, air filter and dryer is important to make sure that they are in good condition every time.
  • Clean the equipments used.
The equipments to finishing materials application may be the source of crater problem. Inappropriate treatment to the spraying equipment such as a lack of cleanliness or lubrication with the oil that not compatible with finishing material materials could cause crater. Make sure to do a good maintenance and cleaning to the equipment. Use the oil that is compatible with finishing material to lubricate the equipment. 
  • Check the finishing materials used
Finishing material can be contaminated when it is stored, mixed or handled.  Since that make sure that the finishing material used is clean and does not contain the chemicals bullies. Check the physical appearance of the mixture before finishing material is applied. If there is a distinctive appearance then it is should not be used.
  •   Clean the operator
Sometimes these contaminants carried by the operator. Therefore, make sure every person who does the finishing process is clean. Blow the body and clothing with air gun, wash the hands using clean thinner before start finishing activates.
  •   Add anti crater additive
Anti crater additive is a substance added in the finishing materials to reduce the incidence of crater. This material actually have been added when the finishing materials is made. If there is crater problem happened, then small amount of anti crater additive could be added to the finishing material. The addition of this additive is just a temporary solution until the real causes of crater can be found and resolved. When the cause of crater problem have been found and can be overcome the addition of anti crater should be discontinued. 
Crater problem is rather difficult to be solved. There are many possibility factors could cause this problem. Sometimes we need a long time observation to find the cause of this problem.  Every possible factor should be observed and checked one by one until we can find the cause and appropriate treatment can be done.
Some crater problem are even gone themselves before we know the real cause.


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