The soft finishing layer problem in the wood finishing.

Soft finishing layer is the problem, when the finishing is touched or under physical pressured, it develop marks, print mark, or finger mark, etc. In the bad mark, the finishing layer could stick to the things put on. If the furniture is packed and wrapped with foam, or paper, then the form mark appears on the surface or the foam is sticked to the finishing. A soft finishing layer is a serious problem finishing, since it makes the furniture cannot fulfill its functions. No matter how good the furniture, it will useless if it cannot hold the thins put on it. 

A soft finishing layer is a failure in the finishing process. The soft finish layer often has to be stripped off and refinish with the right process and the right finishing materials. The soft finishing layer is mainly caused by 2 things: the finish layer that is not perfectly dry and the bad quality of finishing materials. To avoid this problem then we need to make sure that we use the good quality material with the proper finish.

The poor quality of the material, instead off low quality material (mostly because the price is too cheap), can also be due to several other reasons, such as: material that has expired, inappropriate mixing, inappropriate thinner, or mixed material that has already passed its pot life.

The second reason is because the layer is not fully dry, can be caused by several reason such as : too thick coating layers, too rush in process, the incorrect in mixing ratio for catalyzed coating and the incorrect thinner to reduce the coating.

soft coating at the table

Here are some tips to avoid the soft finishing layer.

The soft finishing layer is big problem. If it happened will be costly to repair and fix it. The best option is to do correct process to avoid this problem. 

•  Allow sufficient drying time at each step in the finishing process.

Every finishing material requires a certain time to dry. The finishing materials which is dry with chemical reaction need enough time to ensure its chemical reactions is completely done. While the finishing material that dry by evaporation its thinner also need time to let their solvent to evaporate and release from the layer. The finishing layer will only meet his full strength when he is completely dry. Since that, we need to make sure that the finishing layer is completely dry before the product is used or packed. In a finishing process with many step, we need to ensure that every layer in each step of the finishing process has dry enough before continue with the next step. Every type of finishing material has different characters and may require different drying times that need to be followed. We can find the drying time be the product specifications. It is usually written in the cane of the product, or we can ask to the supplier.

•  Avoid the thick layer of finishing material.

A thick layer of finishing materials tends to take longer time to dry. The thick layer will make the process of thinner evaporation become more difficult. Since that the too thick application should be avoided. One coat or two coat application of clear coating is more recommended instead of many layer in one application. If we need to built a thick film then we can re coat the finish layer after it is dry enough. It is a safer process since the drying process will be easily occurred.

The condition of the finishing room.

The drying process of a finishing layer is highly influenced by the environmental factors, especially the air temperature, humidity and circulation. In general, the drying process can faster in a room with higher temperature and low humidity. The solvent based finishing materials is less sensitive to the humidity, but the water based material is more sensitive to air humidity. We need to consider the temperature and the humidity of the finishing room  when do the finishing process. When the room is humid and cold, it means that we have to provide longer drying time to the finishing process. We may consider to equip the oven in the drying room to better control the humidity and the temperature of the room. 

•  Use the finishing materials type in accordance with the product need.

There are many various types of finishing materials are available which each has its own character and properties. We have to make sure that we use the proper finishing material according to the product need.  The NC finishing materials, shellac, or varnish is usually relatively soft and not strong enough to withstand the high heat and pressure. Therefore, for products that require a higher resistance, it should be finished with the stronger finish material. The PU or AC clear coat is a stronger material that can withstand higher pressures and temperatures then the NC material.

Do some tests and experiments to ensure that the strength of the finish layer used is fulfill the specifications required by the finished products.

Make sure that we use the good quality finishing materials.

The quality of the finishing layer is also determined by the quality of the finishing materials used. The it is always better to use the good quality finishing materials although it is rather difficult to know the quality material by observe it in the wet condition. There are something we can do to minimize the problem of material quality:

•  always check the expiry dates of the materials before we use it.

Make sure the material is not over its expire date. Avoid too old material unless you have enough knowledge about the physical properties of the material. 

• Check the physically looked of the material. 

Avoid to use the materials that is already physically changed since it is usually also has already chemically change.

• Do a proper mixing.

If we want to add some thinner then we have to make sure that we use the proper thinner which is suitable with the finishing materials. The thinner from the same supplier with the type that is recommended by the supplier is the best choice. If we use the catalyzed coating then make sure its mixed in the correct formulation according to the product data sheet. The finishing materials that have good quality will become bad quality if it is inappropriately mixed.

If we have to use the material which is doubtful then try first it in the small panel. Do check and examine the result, make sure the coating is good before apply to the stuff. 

• Be aware with the pot life

For the catalyzed finishing material such as:  melamine, PU, PE or the other 2 component material has pot life. It is the time from mixing the two material mixed together to the point at which the mixed paint is no longer useable. When the mixed material has reached its pot life, its already poor and wont give good finishing layer.