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

Monday, August 23, 2010

Cracking in the wood furniture finishing

Cracking in the furniture

Cracking in the finishing.

Cracking is a serious problem in a finishing. The cracking in the finish layer indicates a failure in the finishing layer. A furniture product with cracking in its finish layer will not be acceptable in the market. A finish layer which has crack in it also can not be corrected again, the only way to treat this finish is to strip the finish and refinish with the new system. By these reasons preventing the occurring of crack in the finishing is much better option.  The cracking problem is mostly caused by the improper process in the finishing.
Here are some of the causes of the cracking in finishing layer:
  •  The cracking in the substrate underneath.
Wood which is not dried properly is one major cause of a movement in the wood product. Wood is a hygroscopic material which will always adjust its moisture content according to the air humidity environment. While the wood adjust its moisture content inside it will shrink and expand make a movement on the wood product.  The movement that is too large can result in a rupture in the wood.
Meanwhile a finishing layer is only a very thin layer. The finishing thickness is nothing compared with the thickness of the substrate. Therefore, if there is cracking in the substrate beneath a finishing layer will be able to withstand it.
To overcome this, the wood need to be dry enough until it meets the proper moisture content to prevent a rupture in the furniture products.
The checking to the wood moisture contents is very important before a finishing process carried out to the furniture. When the wood moisture content is still too high or too low, a wood treatment is better done until it meet the standard moisture content. It is a cheaper option than doing the finishing process and then strips the finish because of the cracking problem in the furniture product.
Cracking is also much found in some special veneer such as crotch, swirl and burl. To prevent the high tend cracking veneer, a special treatment is needed to reduce its cracking tend. The glue sizing process and use of veneer softener is recommended to minimize the cracking problem on that veneer. 
  •  Finishing in a moving substrate.
Sometimes there are moving parts such as seats, seat in furniture that requires a finish layer on it. Sofa or seat made from leather, cane, rattan, hyacinth or other natural products usually need a finishing layer on it. For this case an elastic finishing layer is needed so it can follow the movement on the substrate underneath. Since that finishing on the leather, rattan or water hyacinth is needed a special material with higher elasticity and adhesion power then the wood finishing material. Bu however the elasticity of a finishing layer is very limited, the finishing will not be able to withstand the movement that is too large.
  • Too thick finishing layer
Finishing layer which is too thick, it is very risky to be cracked. The cracking caused by too thick layer of this film can be found several months after the finishing process are finished done.  A clean looked and high gloss finish is high risk to crack since it has too thick film layer. To meet the high gloss and even surfaces most time we apply too many finishing layer, that tend to create too thick film.  So when we make a high gloss and even finish, a level and even surface is better prepared from the unfinished preparation. A good sanding to make a level and smooth surface is better option then try to make level surface with finish layer.
  • The pigment coating is too much
Pigment as a color-forming finishing material. The pigment application always requires a clear coating layer to bind it and make good attachment with its substrate underneath. In a finishing layer the pigment layer should not be too thick in order to have sufficient ties to its lower layer. A pigment layer that is too thick in a finishing process won’t have enough bonds and it easy to crack when it is wet with thinner or coating material. It often occurs in applications of glaze, a glaze is too thick will crack occurs when coated with clear coating thereon. Therefore, avoid staining with too thick pigment application, do a proper pigment application then seal with a clear coating, then another pigment application above the clear coating can be done if necessary to meet the expected color.
  •  An improper or bad quality of material
The quality of the finishing layer is mainly determined with the quality of the finishing materials thereon. So make sure that we use good materials in a finishing process. Always check the expired date, and the technical data sheet of every material before used.
A physically changed in the materials looked is signal that the material is already not in good condition. A test is better done before use this material.
The right mixing especially to the 2 components materials such as P.U., or A.C. is really necessary to ensure that we use the right material. Improper mixing will cause a reaction that is not perfect, this would result in cracking of the finishing layer is produced.
  • The incompatible finishing layers.
Sometimes, we run finishing system that uses materials from a variety of types. If we do this a proper finishing system need to be chosen. Since an incompatible finishing layer will create problem finishing such as cracking or frying. Since that the use of the same type finishing material in a finishing process is highly recommended. If we want to use many type of finishing material, then we need to make sure that the material are compatible  each other.



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