" " wisno wood furniture finishing: Wood filler and putty for wood finishing

Saturday, December 5, 2009

Wood filler and putty for wood finishing

Wood Filler

Filler is a finishing material used to fill the pores and grains of the wood to help to make closed pores finish. In the finishing process for wood or veneer, often we find some wood that has big pores and grains such as: Mende, Oak, Meranti, Teak, Mahogany, etc. To make close pores finish for that wood, we better to use filler to shorten the finishing step and reduce the uses of sealer and lacquer. The wood with big pores, sometimes require 2 times filler application to fill the pores and grain well.
Filler is made from bulking agents, resins, solvents and pigments. Bulking agent is material that has very small shrinkage, when he is dry will stay in the same volume. The bulking agent work to fill in and close the grain and pores of the wood. The bulking agent that widely used is a ground silica which is grounded to a very size fine. Resin that is the binder that binding the bulk agent to have good adhesion with the finish layer. The binding are the same resin to make coating such as: oil, varnish, acrylic or urethane. The type of resin that used as binder will determine the type of the filler and the basic character of the filler. The pigment can be added to coloring the filler if necessary.
When nitrocellulose sealer and lacquer is used to finish for wood with big pores, the uses of filler is absolutely needed to get the close pores finish. For chemical reaction drying coating such as: polyurethane, acid curing, UV coating we still can make close pores finish without filler. But the uses of filler is recommended, because it will reduce the consumption of a sealer and lacquer and it will cut the finishing step. The sealer and lacquer is designed to make the film layers and provide protection to the finishing, not to fill the wood pores.
By its resin ingredient there are various types of filler; acrylic filler, water-base filler, UV filler, PU filler, etc. Meanwhile, according to the way application there 2 types of filler: filler that is applied directly to the raw wood before finishing process begins and the filler that is applied over the sealer or wash coat. The filler that is applied at the raw wood usually requires a good sanding before continue to the next finishing process. While the filler that is applied after sealer is applied like glaze, it is also called as the wiping filler. This filler is poured, brushed or sprayed on the surface, then wiped clean with rag. The wiping filler is easier in application but the filling property is not as strong as filler with to the raw wood.
The cleaning and drying of the filler are very important. Filler must be cleaned properly and ensured only left inside the pores or grains. Filler also must be really dry before go to the next finishing process. Excess filler in the surface will produce bad finishing looked, while the filler which is not dry will cause many finishing problems such as: white in the pores, adhesion problems, bubble, pinhole, etc.

Wood Putty

Putty is made to different purpose with filler. If the filler used to fill the pores or grain of the wood, the putty is a material that is designed to fill and correct the holes or cracks caused by the imperfect or mistake in the unfinished product. Materials to make putty is the same (similar) with materials to make a filler, but the putty is made in he higher solid content and designed to be dry faster. Putty is used to fill the gap or hole in the raw wood. Same as filer the putty need to thoroughly dry and then followed by a good sanding that to make sure it left only in the holes or cracks. There is also a type of putty that is applied over the sealer or lacquer. This type of putty is available in various colors and can be chosen that matches to the desired finishing color.
The use of putty should be considered just to touch up in the furniture-making process, to overcome the imperfect work of the previous process. Therefore the use of putty should be minimize as much as possible. The uses of putty that is too much or too big will ruin the finishing looked. The wide putty will be obviously looked bad at finishing results. The big holes or gap are better corrected with wood. A small piece of wood is inserted into the hole will give better looked in the finishing. The putty with good quality may be able to absorb the stain color to make the color be similar with the wood finishing, but the large putty will still obviously ugly in the finishing look. It is because the putty does not have pores or grain.


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