veneer figure and character

The grain patterns and figures are the most advantage of the veneer. With the veneer the unique wood character and beautiful wood looked can be duplicated with the veneer arrangement. There are some special veneer that have special looked. The exotic wood veneer which have nice, unique and exotic give the flexibility to the furniture designer and furniture maker to bring their ideas of furniture product to reality.

Below are the list of some exotic figure of veneer that commonly used in furniture production.

Veneer setting for wood furniture

Instead of the way wood sliced, there are variation of veneer that based on how to set the pattern of the veneer when it is glued and attached on the m.d.f., particle or laminated wood board. There are many patterns of veneer setting can be created, and each will give the different appearance result. This variation produced by the way it is set gives more freedom to the furniture designers to produce the furniture products in accordance with their ideas.

Several veneer variation base on the pattern of the veneer setting can be seen in the pictures below.

4 wayandbutt

book match veneer

diamond veneer

random match

slip match

V veneer

horizontal leave

checker board

Wood veneer for furniture

The uses of wood veneer in the furniture industry is very common. The price of wood is going to be more expensive now, especially for the wood species with beautiful grain such as: teak, cherry, mahogany, walnut, rosewood. Peoples are talking about keeping the wood and forest to save the earth. Moreover the global warming issues are very strong and popular and influence many aspect in human life. This condition has made strong pressure to the furniture industries. The woodworking industry have do action to save the wood as its main raw material. Since that, more furniture factories use the wood veneer to make panels, board replacing the solid wood. The veneer technology actually actually is not a really new technology, it was already known and developed since the end of 19 century. And now the veneer technology is already very advanced to meet the requirement of furniture industries.

Veneer is wood log that is sliced in to form very thin sheet layer, The common thickness is usually between 0.2 mm to 1 mm. The other thickness are also available but must be special ordered. Wood veneer is usually made of from premium wood that has beautiful grain such as: oak, mahogany, teak, rosewood, etc. Veneer is used to make the wood panels with special grain and looked such as: crotch, burl, swirl, etc.  The veneer has some advantages compared with wood; his price is considered cheaper, the flexibility in arrangement and also the better stability.

Veneer is attached to the core panel to make board panel. The common core for veneer are : m.d.f., particle board, or laminated wood from the wood with cheap price. Sengon wood, or jabon wood are some of cheap wood species that can be used as veneer core. M.d.f. (medium density fiberboard) is processed wood material made from wood pieces cooked in a tank (digester), and then this pulp is passed through a roller to form a board with a certain thickness and sizes. The particle board are pieces of wood that was ground and then mixed with glue and pressed to produce board sheets with a certain thickness and sizes.

The veneers can be arranged to form a certain pattern and produce a more attractive appearance. With many different slicing techniques, veneer is be able to produce many patterns to varied wood looked. This veneer can be more flexible and can be arranged with more varies by optimizing the patterns of slicing and the type of veneer. With a good lamination, the veneer is also more stable than a solid wood board. Wood board has more pores than veneer on m.d.f.; so it has higher risk to the wood movement caused by the changes of temperature and moisture content. Veneer can also solve problems at the difficulties to get a long and wide wood. 
With his  advantages, the veneer is used more to make furniture, especially to make wide, long panels. The furniture industry has replaced the use of wood panels to veneer panels in the manufacture of boards, especially for indoor furniture. For outdoor furniture, the veneer usage is still limited because its not strong enough to withstand the outside weather. The veneered panel for exterior must be made with special glue and special core which could be more expensive than the solid wood.

How wood is sliced to make veneer?

The wood can be sliced in some different way and it will determined the veneer looked. There 5 ways of cutting veneer that commonly used. They are: rotary slicing, flat slicing, quarter slicing, half round slicing and rift cut slicing. 

1. Rotary veneer

Timber is mounted in a certain position and then be rotated so that the blade is driven to cut wood from the outside.

2. Flat slicing

Timber is mounted on a certain position, then be moved to so that the knife cut parallel to the mid line of wood.

3. Quarter slicing

Timber is mounted on certain positions and then move the knife to cut at an certain angle.

4. Half round slicing

Variation of the rotary where timber is fitted with a certain distance from the center of the circle rotation

5. Rift cut slicing

More variation of the rotary slicing, timber is mounted on a certain position, then wood is cut into a quarter and moved around to the knife

Solid content and volum solid content of finishing material

The finishing material is always consisting of a solid material and thinner. The solid material is the paint, coating materials, pigment or the other finishing material which will remain on the surface when it is applied and dry. While thinner is mixed of solvent that all will evaporate when the finishing material is dry. The function of thinner is to reduce the viscosity of the finishing material to make the material is easily applied and handled in the finishing process. The thinner is just a "vehicle" to deliver the finishing materials to its "destination" (the finish surfaces) The thinner will evaporate and disappear in the air during drying of the finishing materials. 
According to the thinner, solvent and finishing materials there are some important terms to be understand, they are: viscosity, solid content and volume solid content. About the viscosity of finishing material we discussed in our article: viscosity of finishing material. Now in this article we want to discuss about solid content and volume solid content.

Solid content

Solid content is the content of the finishing material in the paint or coating mixture. This solid material is the material that will stay and coat the surface and determine the outcome of the resulting finish. Some peoples may still think that the finishing materials with high viscosity will have high solid content. It is not really true. Solid content can not be seen or measured from the viscosity, it depends on the composition of the materials in the paint and the type of solvent that is used to solve the paint. The relation of solid content and viscosity is varying from one material with the other. Every solvent is specific, some specific solvent is needed to solve the specific material. With proper solvent, the material with high solid content can have low viscosity, on the other hand the paint material if it is thinned with improper solvent can have high viscosity although have low solid content.
To find the solid content of a paint we have to measure it. Solid content is obtained by measured the weight of the left paint when all the thinner evaporated divided by the weight of the paint with all his thinner. Weight and record some amount of paint.  Then heat the paint in the oven to let his whole thinner is evaporated. Then weigh the remaining dry paint weight. Solid content is the weight of the paint left when all of his thinner is evaporated divided by the weight of the mixture paint with his whole thinner in the mixture, usually expressed in percent.
To illustrate we can see the following example: 100 grams paint that has 30% solid content means that the paint has 30 grams of a solid material that will left on the surface, while the rest or 70 grams of material is paint thinner that will evaporate in the drying process. From this view it is very logical to be understood that the higher solid content is considered as better paint.  In  the application the more solid material left on the surface will coat the more surface area.

Volume Solid Content

Actually there is another parameter that better describe the quality of the paint instead of the solid content; it is the volume of solid content. Volume of solid content is the size of the volume of a paint that will remain on the surface when his entirely thinner evaporates from the paint. Volume of solid content is measured by measuring the volume of paint in the mixture, and then paint is dried in an oven to evaporate his entire thinner and then measure the volume of paint left. The volume of solid content is the volume of paint that remains divided by the volume of paint with his entire thinner, usually expressed in percent. Volume solid content  better describe the quality of paint because the volume of the finishing material that is left in the surface will determine the finishing thickness. The volume of finishing material left on the surface is  also determining the surface area that can be covered by the finishing materials. The difference between the volume of material and weight of material is a function of the weight and type of material depending on the mixture of ingredient materials used and it is the secret formula from the paint manufacturer.

viscosity of finishing material

Viscosity is an important properties of the finishing material. By the physical and chemical engineering definition, the viscosity is the resistance offered by the fluid to the relative motion of the particles or as the internal friction off the liquid. Viscosity of the finishing material is important properties since determines to a great extent its ability to be brushed, sprayed or dipped as well as its flowing after being applied. Materials with low viscosity will flow better than high viscosity because of less internal friction. From this point it is easy to understand that the viscosity of the material is more important to relate with the method of application of the material. For example the material that is designed to be applied by brush needs different viscosity with materials that designed to be applied by spray. 
Viscosity is not really correlated with the film thickness that will be built by the material. Some peoples may think that the more viscous material then the more the value of the material, because that material must be reduced to a greater extent before it is applied. This may not true, especially in the case of lacquer and synthetic materials. With the advanced methods it is possible to make the finishing materials with low viscosity that can give more film thickness. On the other hand there are many products so viscous that must be much reduced before they applied but have low solid content. The viscosity is also a function of temperature, since that at the time of measuring the viscosity of a certain material, it is recommended to measure and check the temperature of the material. 
It is false economy to figure that because a given product need to reduced at the rate of two parts to one part of thinner it is cheaper than another material which can be applied straight without any solvent. This may not be true, since it depend on the other characteristic of the finishing materials and also the solvent used. Usually the objective to applying the finishing materials is to give the necessary protective and decorative properties demanded by the finish product. If a film thickness or color can be produced in one coat with unreduced material, where two coats of reduced materials is needed, the one coat materials is always cheaper in the end cost, because of the saving labor and total material use.

viscosity cup

There many ways to measure the viscosity, but the method that is commonly used in furniture finishing material is measurement by the viscosity cup. Viscosity cup is a cup-shaped device that has a certain volume sizes and has an orifice with a certain diameter at the bottom. There are various size viscosity cups; the commonly used in the furniture finishing industry is Ford cup, Nk cup and Zahn cup. Each device has a different volume and has a series of orifice diameter, see the picture above. Viscosity measurements’ using this tool is to fill in the finishing material (a liquid) that need to be measured in the viscosity cup fully, then the material is allowed to flow through the orifice until the material entirely out. The time it takes to all the material in the viscosity cup get out is measured and then converted to determine the viscosity of the material. In the chemical or physical engineering viscosity have a unit that is poise (g/cm.second) or lb/ft.hour. But for the measurement of paint or finishing material, usually the viscosity is expressed enough with the time (seconds) and the type and size of the viscosity cup is used. For example a paint material has a viscosity 14 seconds with a Ford cup No. 2, meaning the material as measured by Ford viscosity cup cup No. 2 and obtained a measurement time 14 seconds. This expression is enough to explain the finishing materials viscosity because the specification of the equipment used for the finishing application is also expressed in the same way. The measurement time obtained from each cup will be different, since they has different volume and orifice diameter. The comparison of the measurement time of various viscosity cup is shown in the figure below.

the conversion table for some viscosity cup measurement

Thinner

Thinner is the material that is used to thin the finishing materials and to set specific properties desired during the handling, application or storage. The pure finishing materials such as: pigment, resin, etc. are solid material or thick paste with high viscosity that is very difficult to be applied or even handled. Meanwhile the equipment to apply the finishing materials such as: roller, spray gun or even brush require a certain viscosity to work well. The thinner is added to then into the pure finishing materials to make the finishing materials in the liquid condition and to accord the viscosity material to the finishing equipment wishes. Almost all finishing materials need thinner. The main function of thinner is to dilute the finishing materials and reduce viscosity, but thinner is also added to build some characters of the mixture of finishing materials. Some special character such as: the drying time, film flow, the penetration, and the strength of the finishing materials (in limited range) can be set with the thinner chosen. The amount of thinner that is added in the finishing materials is also used to adjust the concentrate of the finishing materials during the application. Every step of finishing process needs a certain amount of finishing material that laid on the surface to get the desired result. To adjust the thickness of finishing material is done with thinner. If the material is thick, then we can cut with thinner to get the right concentration.

The coating such as sealer and top coat is a mixture of resin with 1 or more resins as the main ingredients, plus some additive substances. The composition of resin and additive mixture varies depending on the type of finishing material such as: polyurethane, nitrocellulose, acid curing, acrylic, alkyd, vinyl, etc. and also depend to the brand. While the stain as a mixture of pigment and binder are also has different composition for each type and brand. Like the finishing material, the material for thinner is very specific depend on the finishing material that need to be solved. Therefore, each type of top coat, sealer, and stain actually need different thinner. Thinner for clear coating is usually called as lacquer thinner, is designed to make the clear coating flow well, and get the right viscosity depend on the application.

The selection of thinner was also used to set and adjust the drying time by finishing material application. The drying time of the finishing material is need to be set depend on how the application. For example for the brush application, we need the materials that need longer time to dry to make the even surface and reduce the brush mark. While the finishing materials for spraying application need dry faster, the longer dry will reduce the speed of the finishing process and also tend to sagging. The selection of the thinner should also look at the conditions in the finishing room where the finishing process is done such as: the air temperature, air humidity, the production speed, the step of finishing and the facilities in the finishing room.

The thinner will entirely evaporate during the drying of finishing materials. He is just like a vehicle to deliver the finishing materials to the finish surface in the application. The thinner will be entirely exhausted and nothing is left at the finish surface. So it needs to be understood that the uses of thinner in the finishing process must be set to be as little as possible. The more solvent is used it means that more money is wasted by being thrown into the air and a less film thickness is being deposited on the work. In judging the final cost of finishing, the original cost should not be considered as the price per gallon alone, but number of coats, the labor cost, time of overhead, the total quantity of material needed to produced the finished, quality of dried films and many other points

Although only the vehicle, but the thinner selection is one very important thing because it will affect the drying speed of the finishing materials and finishing processes and could also be influence the strength and quality of the resulting finish. There are many problems could arise because the uses inappropriate solvent on the other hand, there are many adjustment in the finishing process can be made by choosing the thinner used. 

Thinner ingredients 

Thinner is made from a mixture of solvents, (latent solvent) and diluent. Solvent is a substance that serves to dissolve a finishing material. For example solvent for nitrocellulose is: m.e.k. (methyl ethyl ketone), acetone and buthyl acetate. While latent solvent is a substance that helps dissolve when mixed with a solvent. Latent solvent can not dissolve the material, if not mixed with solvents, for example nitrocellulose latent solvent is methanol, isoprophyl alcohol and butanol isobuthyl. The solvent and the latent solvent are the main ingredient for thinner, some peoples called them with active thinner. The solvent and latent solvent usually are expensive material then into the thinner is also added another ingredient called diluent, a material that dissolves in each other with solvent but can not actually dissolve finishing materials. Diluent is usually the ingredients are cheap and added to the mixture of paint thinner to reduce the price of the thinner. The materials that can be used for solvents, latent solvent and diluent are highly dependent on the type of finishing material. 

How to match color in the wood furniture finishing

The furniture industry today is getting more difficult to find the good wood as raw material for his production. The issues of forest conservation for save the earth has made the wood is more expensive and more difficult to be found. Furniture industry as one of the industries that need the wood encounter many problems with wood, the increasing prices, and the quality of timber that averagely become lower. One of the problems in the wood for the furniture industry is the base color of wood which often vary from one part to another part. The wood color variation is happened even though the wood is the same type. While the furniture market requires the quality product becomes higher and higher. The color of the wood furniture need to be the same all the time for the whole product.

To produce same color or at least a well blended color of furniture products made from wood with varying base colors, some special treatment is required. One technique to make uniform color in the finishing process is by using stains to equate the colors of the wood. We can prepare a special stain to uniform the variation of the wood color. The stain operation to equate the wood variation color is done in the first step of finishing process, before he application of body stain. The body stain is wood stain that applied to get the desired color. Color equaling is more needed when the finishing color is a light transparent color. In the light color the wood base color variation will be looked more obviously. For the dark finishing colors, the color variation will be covered and hidden by the thick and dark stain. For finishing with a solid color the variation color of the wood base is not be problem since it will be covered entirely by the stain (paint).

The color variation of the wood finish

There are 2 kinds of stain that an be used to equate the wood base color, the sap stain and equalizer stain. Sap stain usually is brown color, it is used to bring the wood with light color to go to the dark wood color. While equalizer stains stain was used to tone down a certain colors in the wood that seems striking and disturbing the overall color. The best stain for sap stain or equalizer is stain with inorganic pigments, because inorganic pigment has covering properties better than organic pigments stain. The color selection of sap stain and equalizer stain need to consider with the wood base color and the final finishing color desired. Sap stain is usually in brown color, while the most equalizer stain is green color to cover and tone down the red color. Applications sap stain stain and equalizer is done by dry spray or medium wet spray in the unequal parts, until get the equal color for the whole surface.
See our article : how to match color in the wood furniture finishing

color variation in the white wood

The stain application will make the wood color be more equal.

The uses of the sap stain and stain equalizer is already a standard procedure in the finishing industry to anticipate the variation of wood color. The selection color of sap stain and equalizer stain is part of the whole finishing process. Since that the color of sap stain and equalizer stain is based on the color variation of the wood and the desired final finishing color. One tool that can be chosen to help to select the color of sap stain and stain equalizer is using the color wheel diagram. Usually we need 2 different stains, a sap stain and an equalizer stain to equate the wood base color. But for the extreme conditions where the wood color variation is very far sometimes we need to use several sap stain and equalizer stain.

Step panel for furniture finishing

Color panel

 antique oak color panel

Color panel or swatch panel or standard panel is a finished panel that figure the color, appearance and quality of furniture finished for furniture product. In the furniture business, color panel is a very important, especially when dealing with the production of furniture in large quantities. Furniture product that is sold for furniture market requires a quality standard that must be maintained when the market still accept that product collection. When the market is still want the product, it means that the furniture factory has to make the same product, the same size, same looked and same quality. If the standard of size, model, shape, construction of furniture is shown in the technical drawing or photograph, then the finishing standard is figured out with a color panel. A color panel is the tool to represent the finishing colors and appearance of the product.

There are several types of color panels that are used in the furniture industry: master panel, working panel, salesman panel and step panel. Master panel or main panel is a panel which shows the finishing color and looked for the product. Master panel is an example of the appearance (looked) and quality finishing neede by the furniture buyer. Legally it requires approval from both the buyer and the manufacturer. Master panel is usually made by a furniture factory to get approval from the buyer. Usually the master panel is made from a large panel then cut into 2 parts, 1 part is retained by the buyer and the other part is stored by the furniture factory. Master color panel is considered as document that shows an agreement between the buyer and the manufacturer about the color and looked for the finishing. Master panel can be viewed any time if necessary. The color panel can be use to anticipate the finishing problem if there is any dispute between the buyer and the furniture factory.

From the master panel. then the other panel are developed that are the salesman panel and working panel. The salesman panel is the color panel that is used to help the salesmen in selling products to the users. Usually salesman panel is a small size panel, so it easy to be carried, but with the color and appearance of the finishing describe the appearance of the finishing of the furniture products offered. Working panel is color panel that is used as standard panel for the factory to do the production. Working panel usually is a step panel, a panel that is completed with the finishing step to get the final color and looked. 

Step Panel 

 Step panel

 

Step panel is a color panel that shows all the necessary finishing processes to achieve a certain desired finishing looked and color. Color panel is a model finishing  that shows the color and looked that has to be followed by the furniture product. How to get the color is shown and explained by the steps in step panel. Step panel is a kind of pilot run for the finishing process to obtain a certain finish with a certain wood. The step panel must clearly show the color and appearance of the desired finishing and how is the finishing steps to get the finishing appearance and color. Before the finishing process on furniture product is started, the step panel should be made first. Although it seems it is an extra job to make step panel, but actually it will make finishing job easier. After the step panel is made, then the finishing process for the product just needs to follow the step finishing that shown in the step panel.

In the furniture factories which are produce furniture in big quantities (mass production) the step panel is very important. There will no finishing process start before the step panel has been approved. For small-scale production step panel is still necessary because this panel is a guide on how to do a finishing process to produce the color and appearance of the desired finish. Step panel is a document that can be seen and review if necessary when there is a finishing problems. Step panel can also be stored as a document of a finish when later we need to make finishing with the same color and appearance.

When we make step panel we need to consider to the condition and facilities that is available in the finishing room. We need to ensure that the finishing step in the step panel is really applicable in the production. The substrate for the panel should be the same with the substrate that will use for the furniture product. How to prepare the step panel such as the sanding, the distress, is also need to follow the production. For furniture product with certain forms such as carvings, arches, profiles or veneer with a special arrangement, the step panel needs to represent the forms of furniture product. The step panel also should be completed with the explanation of the material used, how the application techniques and other technical data such as the viscosity of the finishing materials, the drying time of each process, and other necessary information to do the process.

Step panel for gold finish

step panel for cherry wood finish

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.

Sandpaper for wood finishing

The sandpaper
 

Sandpaper or abrasives is the material to sand any surfaces to make a smooth, even and level surface. In the wood finishing the sandpaper is also used to do the highlight and rubbing the finish. Basically sandpaper is made of 3 main components that are: minerals, bond (coat) and backing. The properties of sandpaper actually determined by and depending on the type of his constituent components and how they are unified.

The diagram of sandpaper

Minerals is the abrasives part to rub and sand the surface.  The mineral is made form hard material that is grind-ed to make a grain form. There are available some materials that can use for make abrasives, the most widely used are: aluminum oxide or silicon carbide that is pulverized up to a certain size. The size of mineral will determine the grade of sandpaper that shows the roughness of the sandpaper. Grade of sandpaper ranging from 0 as the coarser and 2000 as the finer. There are different standard of sandpaper grade The US, Europe and Japanese. The detail about the grade of sandpaper vs. the size of mineral can be seen in the table of comparison of sandpaper grade below.

The comparison of sandpaper grade

Each type of mineral has different properties. Aluminum oxide is less sharp but more durable. Sandpaper with aluminum oxide is more suitable to do the primary sanding as the sanding for the raw wood. It is used to sand the wood panels or components out from the  machinery. While the silicon carbide mineral has a sharper edges, but it is more easily to be blunted. Sandpaper with silicone carbide mineral is more suitable for sanding at the final process of wood sanding. The silicon carbide is also the mineral to make the sandpaper for sanding sealer or top coat in the finishing process.
Backing or buffer is a substance where the abrasives mineral is attached. Backing for the sandpaper is usually made of cloth or paper with different thicknesses. The type and thickness of the backing will determine the strength and flexibility of the sandpaper. The more flexible of sandpaper is the less strength and less rigid the sandpaper. Sandpaper with the thick backing and rigid is more aggressive. It is suitable to do the calibration and to form the wood component. The sandpaper with thick backing is mounted at the wide belt sander to do the surface calibration to make wood panel.
Meanwhile, the flexible sandpaper is more suitable to sand the complicated parts that can not be sanded by flat sanding machines, such as the: carving, posh, curved, etc. The flexible sandpaper is used to fill the brush sander to sanding the uneven parts. 
Now there are scotch brite and sponge sand, the more flexible abrasives to sand the more difficult form. Scotch brite is the abrasives which is made from synthetic fibers which is coated with minerals. While sponge sand is a sandpaper with sponge as the backing. Scotch brite and sponge are very flexible to reach the inside of the carving or crevices that are difficult to be sanded by rigid sandpaper.
Minerals are attached to the backing with tie or bond. There are 3 types of sandpaper according to its bond, the resin bond sandpaper or glue or a combination of both. According how the minerals is attached to the backing there are 2 types of sand paper, the open coat and closed coat. Closed coat sandpaper is the sandpaper when the entire surface of backing is covered by the mineral. while in the open coat sandpaper, only a portion (40%-70%) from the surface of the backing is covered by the mineral. Closed coat sandpaper is suitable for sand the strong and hard material but the material does not tend to stick on sandpaper. This type sandpaper is mostly used to sand the surface of raw wood or veneer. While the open-coat sandpaper type is more suitable to sand the surfaces when the material tends to stick to the sandpaper. This open coat sandpaper is more suitable to sand the finishing material such as: paint, sealer or lacquer in the finishing process.
During the sanding operation, there is heat generated by the friction between the coating and the abrasives. The excess heat will make the coating to melt and tend to attached to the sandpaper. In the sandpaper sanding is added the additive agent to reduce the heat caused by friction between the sandpaper and sealer or lacquer. The material is called a sanding agent and it is the same material with a material that is added to the sealer for the same purpose. The materials that are widely used as sanding agent are the: zinc stearate and aluminum stearate.
There are also available the waterproof sandpaper that is designed to do the wet sanding. It is used waterproof bond and backing. Wet sanding is sanding process which use the liquid to reduce the heat arising during sanding process. The wet sanding is done when the more smooth and even coating surfaces is needed. The wet sanding is the first step in the rubbing process to produce a high gloss finish when the smooth and flat surface is needed.

How to sand unfinished wood furniture

To obtain a good finish, the wood always requires good sanding. The sanding should be done properly before starting the finishing process. The purpose of sanding is to get a even, smooth and clean wood surface. The process of sanding should be done properly in order to eliminate the knife or machine marks and stains marks  or glue that arise during the process of making furniture. This sanding process is very important because some stains or scratches were left on the wood surface will appear more clearly after finishing process. The fact is lot of finishing problem is caused by the sanding process. When the problem is discovered after the finishing process is done, then to fix it we need to do re-sanding and re-finishing. It its tough work, wasting time, energy and materials. An unfinished product should be assured is completely meet the desired quality before the finishing process. 

To meet the desired quality standards then the sanding process should also be done in accordance with the correct process. Here are the things that must be considered in the process of sanding to the wood furniture:

  hand sanding on carved wood

1. Do sanding gradually sanding using sandpaper from coarse grade of sandpaper to fine grade sandpaper 

Each sanding is always going to leave the lines used sandpaper scratches. Scratch size depends on the grade of sandpaper is used. To remove the sanding scratches that the former will require subsequent sanding with finer sandpaper to obtain a surface with scratches that will not appear again in the finishing process. Selection grade of sandpaper on a sanding stage should not be jumping too far from the grade of sandpaper is used before, because it will lead to imperfect results. Wood out from the machine should be sanded with coarse sandpaper, starting with 80 or 100 grade, then followed by sanding with 120 grade sandpaper, or 150, followed by sanding with 180 grade sandpaper with, and if necessary continue sanding with 240 grade. Final sanding before finishing process is usually sufficient with sandpaper 180 or 240 grade. 

 sanding with orbital sander

2. Try as much as possible sanding by machine. 

There are many sanding machines are available to help the wood sanding to be done quickly and consistently. Many types of sanding machines have been made to facilitate the sanding in accordance with the form or shape of goods. The wide belt sander or a stroke sander is great for sanding panels. For the special shape there are also available the complex machinery such as: spindle sander, brush sander, edge sander, etc. To work with a small sanding or to touch-up work also has available hand sanding machine (hand sander). 

3. Recognize the types of wood 

There are many types of wood, each of which need to be sanded in different ways. Soft wood such as: aghatis, pine or sengon will make sandpaper to dull faster than hard woods such as mahogany, teak, oak, mende, etc. The properties of each type of wood are varying, then it should always be identified properly in order to make optimal sanding process. 

4. Sanding to do as much as possible when a component item
 

Sanding the components will be much faster and easier to do than when goods are assembled into ready-made goods. Therefore, sanding should be done perfectly before it will be assembled components. Sanding for the the assembled goods are so should only for touch up work to revise the workmanship missed job such as, cleaning glue, sand the putty, etc. 

 Check the unfinished wood with lamp

 check the sanding with stain

 

5. Use tools to help to check the sanding results 
 

To avoid waste due to the imperfect sanding should be a good check on the goods before continuing to the next process. To better check the sanding quality we can use light, directed to the surface of wood. The light will help us to better view to check the sanding result. We can also use thinner or thin stain applied to the wood surface to help to see the scratches or stains on the wood if any.