Brush sander for wood furniture

Sanding is very important in the process finishing. The finishing quality is highly determined by the quality of sanding. The sanding to the unfinished wood and sanding to the clear coating both are very important to produce the product with good quality finishing. In the furniture industry which has big volume production, the sanding processes are done with sanding machines as much as possible. The uses machine to substitute the human will ensure the sanding process can with quickly and consistently. One of the sanding machine is designed to do the process of sanding in the furniture manufacturer is the brush sander. Brush sander is a tool to assist the process of sanding to the product or item with complicated form and shapes. The carved product, profile form component, or other irregular shapes can be sanded by brush sander. 

Brush sander is a sanding machine that does not use pad as a place to attach the sandpaper. The abrasives are cut into small pieces and fitted with a fiber as a buffer to form brush-like sander. The brushes of abrasives rotate to do the sanding process for the desired surface. It can do the sanding process to on complicated form objects. The brush of sandpaper is very flexible to reach the inside the profile, carved and the complicated form object without damaging the shape and profile.In further developments there are some models of the brush sander. There is brush sander that designed for sanding the panels with an uneven or profiled surface. The machine is widely used to do sanding process in the flat line finishing line. It mostly used in the UV or water based finishing line. Brush sander is used to replace the wide belt sander to sand the sanding sealer, top coat, or other clear coating between on the roller machine when the uneven surface panel products are finished. The hand scrapped parquet flooring, distressed parquet flooring, the profiled door or the other uneven form panel can be brush sanded in the finishing process. The brush sander machine is more flexible to do he sanding to the uneven surface without any risk of over sanding.

brush sander for uneven panel

The other type of brush sander is the brush sander with rotate wheel to sand the three-dimensional item with irregular form. The carved item, profiled posh, or the other complex three dimensional forms can be sanded with this machine. This machine is more manually tool, the operator is needed to direct the object to the sanding machine. It available in many sizes the small sizes is a portable device to do the sanding in the small object. While the bigger size machine available to sand the big items.

brush sander for three dimensional items

Attentions in the uses of brush sander

• Brush sander machine has very little aggressiveness.

The brush sander machine can not do the sanding to form the objects and profiles. It can not clean up the putty, filler either clean up the chatter marks, knife marks or deep scratches. The correction to the putty or uneven shapes must be done hand sanding with or hand block or portable hand sander with have pad sander. Brush sander will only smooth the surface by cleaning or cutting the wood fibers in the wood surface.
The sharp knife or chisel should be used to make a carved form, profile or other complicated form product. The sharp knife and the right cutting and carving is the best ways to produce the perfect shape faster with better result. The shape correction in the sanding process requires a lot of effort and energy and usually will not give the perfect result.

• Use the grade of sandpaper properly.

The proper grade of sandpaper is needed in the brush sander machine. The cloth back sandpaper is mostly used. To sand the raw wood, the 150 to 240 grade cloth sandpaper back is mostly used. While to do sanding in the finishing process, the stearated sandpaper is needed. The scotch brite also can be mounted in the brush sander to do the polishing.

Electrostatic coating for wood furniture

The spray application technique that could produce finishing layer with the best result has disadvantages, that is the low efficiency of material transfer. The spray application will give material transfer efficiency about 30%-60% and this figure will be even lower if the sprayed object has small surface. If the spray spreading of the spray gun is wider then the surface area of the painted object, then the more material spread to the air. Small surface objects such as: crib, chair, rattan, posh, chair are wasting more material in the application. The electrostatic spraying equipment is the modification of the spraying equipment to give better efficiency material transfer especially for the small surfaces object. ( the electrostatic spraying equipment)

 

Electrostatic coating
 

The electrostatic spraying equipment work by charged the finishing material to be the electrically charged objects. While the sprayed object is grounded to act as the other  electrically object. When the finishing material is sprayed there will be electrostatic attraction force between the finishing material and the object. 

To work with the electrostatic spraying equipment we need special finishing material, it is the electrostatic coating material. The electrostatic coating is the coating that will act as an electrically charged object when it is given the electric charged.  

The electrostatic coating is regular coating that is added with some additive to increase its electrical resistivity. The high electricity resistivity material will make the material become better electrically charge object when it is electrified in the electrostatic spraying equipment. The electrostatic finishing material are only available in the film forming material such as sealer, top coat, enamel or base coat. The finishing material that dose not form film coating such as: wood stain and glaze are never work with the electrostatic equipment.

How to use electrostatic coatings.

• Check resistivity of material

Check and measure the resistivity of the material mixture, make sure it according with the resistivity needed by the spraying equipment. The measurement can be done using the ohm meter.. In general, the higher resistivity material is better since it will generate more electrostatic charge. To increase the resistivity in the mix we can use the solvent that has high resistivity such as Buthyl acetate or xylene. But usually the paint company has added some additive to increase the resistivity. We also can add some more additive if necessary.

• Check the viscosity

Spray gun used in electrostatic equipment will work properly only when the material has proper viscosity. Check the viscosity of the mixture; make sure it is according to the specifications of the spraying equipment used. Use special thinner to reduce the mix since the thinner will affect the electrical resistivity of the solution

• Spray techniques.

In the electrostatic spraying equipment, the finishing material will be attracted and wrap the object. We don’t need to spray overlapping as the conventional spray technique. We can reduce the spray gun stroke to get the same result with the conventional spray. The spray techniques should be simpler and easier. The spray gun distance also cannot be too close. We need to adjust the spray gun movement to get the maximum result.

Roller coating machine for UV coating.

Roller coating machine is the most appropriate machine for the application of UV coatings. Although theoretically the UV coating can be applied by spray, but until now it is always applied by roller coating machine. The curing of the UV coating that requires UV lamp with certain intensity make the  spray applications becomes very difficult. The low efficiency  of the spray application (30%-60%) which is much lower compared with the roller application (about 90 %) has made the roller application is the only choice for the UV coating. Since it cannot to be used for the shape form, then the UV coating is limited to be used for the flat panels. The shaped, curved and complicated objects which only can be finish by spray, are finished with other finishing material. The PU or AC or NC can be used to finishing on the curved part, while the flat surfaces such as top panel, side wall panel can be finished by UV coating.
The roller machine now also has been improved lot. There are many models and variation of the machine has been developed to meet the current needs from the finishing process. There two important  tool in the roller coating machine, the roller and the oven. In the flat finishing line the UV oven lamp are always installed after the roller. The UV oven lamp is used to cure the UV coating that was applied by the roller. In the UV coating finishing process, the water based stain is mostly used as the first step. The water based stain need heat oven to facilitate its drying. So in the first  roller, the sponge roller is used to apply the stain then followed with the heat oven. Then at the next step the rubber roller and the UV lamp oven is used to apply the UV finishing material (UV filler, UV sealer or UV top coat ). In the line there could be some brush sander or wide belt sander are mounted to do the sanding process if necessary.

Roller coater
 

Roller coater is the device used to coat and layer the UV coating to the surface. It works with the same principe with the roller to apply the wall paint, but it work automatically to do the finishing process for wood panel.The roller is wet with the paint and rotating automatically with constant speed, while the wood panel are inserted to be layered with the paint. It is very similar with the roller coater for water based coating, but with different type of roller and oven are used.

There are several types of rollers that can be used in a roller coater machine; sponge roller, rubber roller, steel roller and laser roller.

•  Sponge roller

The sponge roller is the roller with the highest flexibility. Sponge roller is widely used to apply the water based coating. In the UV finish, the sponge roller is used to apply the water based stain at the first step in UV finishing system. Sponge roller is also used to layer the UV sealer on the uneven surface panels such as the hand scraped (distressed) wood flooring panels. The sponge roller has high flexibility so it can accept the slightly bumpy and the uneven surface. But for the flat surface it will produce coating layer with more roller mark.

• Rubber roller

Rubber roller is the most widely roller to apply the UV coating. UV sealer, UV filler, putty and UV top coat are usually applied with rubber roller. Rubber rollers has some hardness sizes that is described with the rubber shore. The application of UV sealer, UV filler and UV putty are usually done by the softer rubber roller (20-40 shore). While the UV top coat is applied with the harder rubber roller (40-50 shore).

• UV laser roller

It  is a special roller for application the UV laser coat. The UV laser roller may superimposing the finishing materials with higher thickness in one application. UV laser coating is designed to produce better flow coating layer better then the conventional UV coating. The UV laser coater is needed at the final coat to apply the UV laser coat to produce more flat and smooth coating film.

• Steel roller.

The steel roller is only used in the application of filler and putty. Steel roller is mounted after the rubber roller or sponge rollers before the UV lamp oven. Steel roller serves to press the filler or putty  into the pores and grain and simultaneously reducing the excess wood filler on the surface.

• Wide belt sander or brush sander

Wide belt sander is usually installed in a series of flat line roller machine to do the sanding process. The UV sealer some time need to be sanded and it should be done automatically by the wide belt sander in the machine line. Sometimes the  wide belt sander is replaced with the brush sander. The brush sander is required to do the scuff sanding. Brush sander is used when the uneven flat surface is finished such as in the hands scrapped (distressed finish).

• UV curing lamp

The UV curing lamp is the device to provide UV light in some intensity.  The UV light radiation is danger, it  causes cancer if irradiate the human skin. The UV oven lamp is always placed in the close box. Since that the UV oven lamp only accept the flat panel form, the UV oven  to the big and curved form stuff will be very expensive. It is the main reason why the UV coating is only used for the flat panel.

There are 2 type of UV cured lamp. The Hg lamp and the Ga lamp. The Hg lamp is the most used, it is relatively less expensive and work for most UV coating. The Ga lamp is used when the coating layer is thick or need the better UV radiation light. It will help to better curing since it can deep penetrate into the coating better than the Hg lamp. It is used for some cases when the UV coating need better curing, for example the UV white base coat, or UV coating with thick film coating. 

UV roller coating roller machine

UV coating for furniture finishing

After long time have been using for wood flooring, UV coating also further developed to be used for wood furniture finishing. It is specially design UV coating and have different specification with the UV coating for flooring. The finishing layer for furniture does not require hard and strong coating film as the finishing for flooring, but better looked. The furniture need more subtle, smooth  film layer with less roller marks. The UV coating for furniture is the UV coating material that is designed to give better flow then the UV coating for flooring.

UV coating for furniture finishing is very suitable to finish the flat panel product especially with big volume. The cabinets, tables, boxes and other flat panel can finished with UV coating  with roller coating machine. The knock down furniture are finish in the panel form, then assembled after they are fully finished. With the roller coating machine, the finishing process can be done very quickly and consistent result and high efficiency of material transfer.
Boards and panels must have same thickness to be able be finished with roller coatings effectively. The unevenness at the panel will resulted to uneven coating thickness layer that will give imperfect finish. The variation in the thickness cannot be allowed since will result in an uneven paint application. It cab be problem in the production. To make the even and flat panel could be difficult. The panel and board in the furniture panel are big and wide which is rather difficult to be handled than the flooring parquet flooring which has smaller size. We need a precise machine to do the calibration to feed the roller machine.
The application to the UV coating for furniture are the same with the application of the UV coatings for flooring. The material is applied by roller coater and then passed in the  UV  lamp for the curing. In the finishing line, some wide belt sander or brush sander could be inserted to do the sanding in the finishing process. The machine setting is also the same with the UV coating for flooring. We also need to apply in the coating in the thin layer to minimize the roll mark. We can adjust the intensity of the UV lamp to set the curing of the coating to be semi cured, surface cured and fully cured.

 Roller machine for UV coating

UV laser coating.

The UV laser coating material is a modification of the UV coating to produce smoother and flat film surface. The coating is specially design to fulfill the requirement in the furniture finishing which need better appearance. It can be applied little bit thicker, and it will flow to make a smooth surface with less roll mark. The UV laser coating has to be applied with the laser roller to get the maximum result.  Laser roller is a special roller, it is designed to hold and apply thicker material on the application but with less roll mark. In the finishing line, we have prepare some spaces to let the wet coating to flow to make a smooth and even surface before dried with uv lamp.   

The UV coating for furniture is however limited to finish to do the flat panel. It cannot finish the curve shaped furniture. The shape form such as leg, carved furniture, posh and built up furniture cannot be finished with the UV coating. The UV coating is also limited to do the relatively simple finishing model. Finishing with relatively clean and even colors or finishes that require a thick layer film is the most suitable for the UV coating. UV coating can produce a thick film finish with high speed and high efficiency. The UV coating can is relative safer than the NC or PU coating to make thick film finish. It can produce thicker film layer then the other finishing material safer and faster.   

The antique finishing  or a special finish that requires a lot of handwork cannot be done with the UV coating. The handwork is very limited since the finishing process is done by automatic machine. The UV coatings can also be used in combination with the finishing materials with other type. The UV coating as the sealer in the first step and followed by application of sealer or top coat with other type sometime is done by some furniture factories. The PU, NC, AC or water based coating can be layered on the UV coating with good result. The point is we have to ensure that the UV coating is fully cured and has been well sanded before layered with other clear coating.

UV coatings for wood flooring.

wood flooring

UV coating (UV cured coating) is the most widely used finishing material for wood flooring. UV coating can produce a finishing layer with very strong film layer. its film is hard, and has high resistant to scratches, heat, solvents and chemicals. It is proper material to finish the wood floors. Floor as the base of the house should be able to withstand the weigh of every items placed on it. Floor also has to accept the activities of the inhabitant in the house. The floor also needs to be swept, mopped and cleaned that is done with water, soap or chemical. Since that it needs a special finishing layer with high  resistant to the water, solvents and chemicals. UV coating can produce a strong film layer that fulfill required by the floor. It can also be applied with very high efficiency by using roller coating machine. Wood floors are always in the form of a flat panel that is very suitable with the roller coating machine.

There are many type of UV coatings have been developed and available in the wood coating industry, but now the most uses is the UV coatings for flooring. It is the UV coating that is specially design to finishing the flooring.
UV coating for floor is already well known since long time, even the UV coating is very identical with wood floor finish. It is the UV coating type that can produce the hardest and strongest dry film. The major disadvantages is that the coating will leave roll marks on the resulting film layer. Even with the advanced technology of wood coating today the marks has become less visible and vague, but of course it won,t  produce a smooth and flat surface as the coatings applied by spray.
The UV coating usually is applied with a roller coating machine. The machine usually is a series of some machines to do the application continuously. It consist a  roller to apply the coating, UV lamp oven to cure the paint and wide belt sander to do the sanding between the process. The wood panels that enter the machine follow the continuous finishing process. Exit from the machine in the wood panel is already finished with dry coating layer and ready to be used.

The process of finishing to the wood flooring is usually as follows: stain, UV filler, UV sealer and UV top coat. The stain used is usually water base stain which is applied by a sponge type roller. The stain is also can be applied by spray outside the machine line. The sponge roller as the first coater is usually equipped with heat oven to facilitate the drying process of the water base stain. 

The application of filler, sealer or top coat is done by using a rubber roller and always need to be followed by the UV lamp oven to cure the coating. Too thick layer of sealer and top coat application should be avoided since it will leave roll mark; the thicker layer the more obvious roll marks is left. Therefore, in the wood flooring industry, usually we needed several times application of sealer and top coat to minimize the roll marks.
UV paint coating will never be dry if it is not lighted by UV ray with enough intensity. Every application of uv coating always need an UV lamp oven. The intensity of the UV lamp oven can be adjusted according to the curing needed. There are three types curing of the UV coating: semi-cured, surface cured and fully cured. 

• Semi cured

It  is a state when a uv coating has not dry. The coating film obtained cannot be thinned with thinner but it is still soft. The film layers will be peeled off when scratched strongly. The semi cured film cannot be sanded. The semi cure is prepared for the film that will be layered with another UV coating without sanding operation.

• Surface curing.

Is a condition where the surface is dry but its film has not reached its maximum strength yet. The coating film can still be scratched. The surface coating is used when we need do the sanding to the coating layer. Some finishing process require certain type of sanding sealer that need to sanded to produce a finishing layer with strong and even film layer. Each film layer that need to be sanded should be dried in the surface cured state.

• Fully cured.

It is a condition in when the coating layer has produced film layer with its maximum strength. The finish film is perfectly dry and will be very strong and hard.  The fully cured is needed on the final top coat application. The fully cured on the sealer will make the sealer become very hard and difficult to be sanded. A fully cured coating should not be re coated without a good sanding process. Every re coat operation on the fully cured UV coating should be started with a good sanding on the film layer, otherwise a poor film adhesion will be obtained. 

Antique gold finish

There are several models of gold finish on the wood finishing. Now we want to discuss about a gold finish with antique impression. It is the gold color which impress the old and dirty looked. The antique looked is made by the glaze application and some physical distress and some sand trough to the gold layer. Principally the antique finishing for the gold is created as a antique solid color. The gold color can be considered as a solid color or paint color finish. The antiquing can be done with the sand trough to the gold color and followed by the glaze application. 

 step panel for antique gold finish

 
Here is the finishing process step by step:

• Physical distress

Physical distress done in order to enliven the impression of the antique. Beat and hit the surface by chain, rock and file little bit to make some damage on the wood surface. Sand the wood surface to smooth the distress marks.

•  Red base coat application

The red is the most widely used as the base color under the gold finish. Traditionally the red color will strength the gold color on it. In the antique gold finishing the red color will come trough when it is highlighted. The red color will produce a nice combination with the gold color above.
A red color base coat is applied by spray evenly allover the surface. Let it dray and do sanding on the red base coat layer. Then repeat the application of the base coat until we got an even red color and with even surface. Usually we need to apply 2 or 3 layers of base coat to obtain a smooth and even red color.

• Sealer application

Application of sealer is used to coat and protect the base coat and produces a smoother surface before the application of gold leaf. Sealer is applied by wet spray coat. Wait it to dry and do scuff sanding to prepare a smooth surface for the gold leaf application.

• Application of gold paint

In this finish we use a gold paint for the gold color. Gold paint is applied by spray evenly to the entire surface. Wait the gold paint to dry. And then do highlight by do sanding on the gold paint layer.

 sand trough on the gold paint to show the red base color

•  Sand trough

Sand trough is sanding the gold layer to open the gold color in some parts. The rubbed gold paint layer will display the red base color. The combination of gold and gold colors will produce gold finishing with life and  interesting antique looked.
Do the sanding on the surface of gold carefully. Use sandpaper with # 360 ​​or # 280 grade. Rub to the outer edges parts of the gold paint. Do the rub trough naturally as much as possible to make an impression of paint wearing since of age and usage. The finishing appearance is largely determined by the rub trough in this step. Check the antique resulted, make sure it seem as we want before we continue with the next process.

• Sealer application

The sealer coat is required to give protection to the gold color. Layer a coat of sealer by spray wet evenly. Wait it to dry, then we can continue to the glaze application. We do not need to do sanding on this step. 

 glaze is brushed to fill the crevices inside the carving

•  Glaze application

The glaze is used to generate more antique impression in the finishing. In this finishing we use a black-gray powder glaze to mimic the dust looked. Glaze is brushed evenly to fill inside the crevices in the carving.
Wait for the powder glaze to dry then highlight by using steel wool. Wipe and remove the glaze on the outside part and leave the glaze inside of the carving. We want to make a old looked dusty gold finish.

• Sealer

The sealer application is needed to protect the finishing looked. Apply a layer of sealer by spray evenly to the entire surface. Wait the sealer coat to dry, then scuff sanding the sealer to prepare a smooth surface before the top coat application.

• Top coat

Top coat as a final layer which provide a protection to the finish and form gloss. In this antique finish model we can use a low or medium gloss top coat.
Apply the top coat by spray evenly to the surface overall. Wait the top coat to dry and the finishing process is completed.

the antique gold finish