Grinding machines can produce excellent results, but they can often cause bad surprises.
We'll tell you how to avoid the most common mistakes when using them.
If you do it right, sanding yourself will give you a very smooth surface. If you make even a slight mistake, you will have to correct the defects.
The tips below will help you minimize this risk.
Correspondence of abrasive grain size to wood properties
Potential problem: Having decided that you would rather sand fine-grained woods like walnut and cherry with fine-grit paper, you put a sanding drum in the drill chuck and wrapped it in a fresh piece of 220-grit sandpaper, or attached a new disc to the back of your random orbital sander and started sanding, pressing the piece firmly to quickly remove saw marks on the edges. Suddenly you smelled burning wood. The top photo shows the result of such grinding, only slightly exaggerated for clarity. Such a part usually has to be thrown away.
Correct method: Avoid the problem by using sanding discs or drums with a coarser abrasive, such as 80 grit. After turning on the machine, move the part evenly, avoiding strong pressure, especially at the ends. The part must be moved at a constant speed, without stopping, to prevent burns.
Vertical spindle machines with an oscillating drum are better at sanding hard and dense woods. Moving the spindle up and down helps dissipate the heat generated during grinding, unlike a conventional sanding drum mounted on a drill press, but even then the part must be constantly moved.
If you need to sand the contours of a sawn part to the template lines, first saw it with a minimum allowance (no more than 1 mm) in order to minimize grinding time and prevent overheating.
When is hand sanding needed?
Potential problem: You sand a primed surface or dry coat of varnish before applying another coat using 220-grit sandpaper. The abrasive accidentally rubs right through the varnish coat and touches the stained wood. Now you will have to completely remove the coating to bare wood and start finishing the damaged surface again.
The correct method: First, determine whether intermediate sanding of the finishing layers is necessary.
Coatings such as nitro varnish partially dissolve the previously applied layer, so you can do without sanding. If you choose polyurethane without sanding, apply a second coat immediately after the first has dried, which usually has a rough surface. After the second coat has dried, lightly sand it by hand with a 320-gauge abrasive to create a rough surface for strong adhesion to the next coat. Ready-made compositions for priming wood require especially gentle and careful sanding.
Processing along the contour
Potential problem: You are grinding a workpiece with a long, smooth curve on a vertical spindle machine. When you stop to admire your work, you discover that the curved edge is full of ugly imperfections.
The correct method: in this example, for clarity, we showed a slightly exaggerated result of such grinding. Always use the largest diameter sanding drum to fit the bend radius. Instead of machine grinding, you can successfully process such parts by hand, using scraps from cutting out a curved contour.
Use coarse sandpaper to remove sawing marks from the edge of such trim, being careful not to change the outline of the edge. Then stick alternate strips of sandpaper onto this edge, successively increasing the grit number from 60 to 180-220 units.
Sand the veneer carefully
Potential problem: After gluing the edge caps to a thin veneer fly, you are going to remove the exposed edges of the trims with a sander. In one place, which took a little more fiddling with, the veneer on the part was rubbed right through, exposing the lower layers of the substrate. The correct method is to avoid tilting the sander when it is at the edge of the piece or pressing it against the surface to avoid damaging the thin layer of veneer and the glued edge trim. If you're concerned about accidentally ruining your work, sand the edge strips flush by hand using 220-grit or finer sandpaper.
You can also cut off the excess veneer with a chisel, pressing it flat against the surface of the piece, and finish sanding with 220-grit sandpaper.
How to keep the surface flat
Potential problem: When gluing a panel of planks of the same thickness, it is not easy to achieve a perfectly smooth and flat surface with invisible glue lines. And if you move the sander back and forth along the glue seam for a long time, trying to smooth out the unevenness, you can get an even worse result - uneven glue lines turn into noticeable depressions.
Correct method: Sanders (especially belt sanders) are not the best way to level surfaces. When gluing the board, carefully check all the glue seams and adjust the position of the individual planks before the glue sets.
If the problem cannot be eliminated in this way, then after drying the board, use an eye gauge to determine the boundaries of the strip, the width of which is approximately twice the width of the sole of your sander on both sides of the adhesive seam, and process the surface gradually, moving the tool in zigzags across the gluing line to above it no depression was formed.
How to Keep Your Profile Clear
Potential problem: Are you confident that you can hold the sander at the same angle while running to get all the grooves on the profile piece? Unfortunately, the profile lines lost their clarity, and flat areas appeared in convex areas.
The correct method: for simple profiles (for example, fillets or fillets), make a profile sanding block from dense foam, shaping it with a band saw and applying sandpaper (some types of glue dissolve the foam).
Another way to achieve an excellent result is to divide a complex profile into several simple parts and process each of them with a separate profile block of the appropriate shape. This is not a very fast way, but it guarantees clear lines and smooth curved surfaces of the profile.
Materials from the wonderful magazine for carpenters and cabinet makers WoodMaster were used in preparation.
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HOW TO GRIND WOOD CORRECTLY
After completing the part, its surface must be thoroughly sanded.
The trade also offers wax, which needs to be diluted with water. When diluting the wax, try to achieve the shade you need so that you don’t have to redo the job later. The finished wax is applied in a very thin and even layer.
But no matter what type of wax you use, the wood must be left to dry after coating for at least an hour so that the wax is absorbed. Then the excess should be removed, otherwise it will resemble greasy spots. After this treatment, the surface will become matte.
If you want to achieve shine, apply wax a second time. Since the pores of the wood were filled with wax even when applying the first layer, only a small amount of it will now be absorbed. A film will remain on the surface. This layer is not wiped, but treated with a coil of thin steel wire (000 or 0000) or cloth - just as shoes are polished after applying cream. If the surface becomes too shiny, take a new roll of wire or turn the felt over to remove excess wax.
WAX FROM TURPENESS AND BEESWAX
Although today you can buy furniture wax without any problems, some home craftsmen prefer to use a homemade solution. Especially when a large amount is required. In this case, making your own mixture may be more financially beneficial than buying a ready-made one.
To prepare a composition for coating furniture, you will need beeswax and turpentine as a solvent. Beeswax comes in different shades of color - from straw yellow to very rich orange. If you have to process light wood, the color of which you would like to preserve after applying wax, you can use bleached wax to prepare a homemade mixture.
The wax mixture gives a stronger, more durable finish if you add a little carnauba wax, a fairly hard tree resin.
WATER BATH
To prepare the mixture, take the prepared wax and chop it with a knife or chisel. Then place in a jar with the same amount of turpentine and heat in a water bath over low heat. Once the wax is completely melted, remove the pan from the stove. Add wax to the hot mixture a little at a time until you get a thick paste. Stir it well with a wooden stick.
Only after complete cooling can you judge the consistency of the mixture. If the furniture wax you prepared seems too thick or thin, add - again in a water bath - a little turpentine or crushed wax. Whenever handling a hot mixture, turn off the stove, otherwise the turpentine may ignite. Store furniture wax in a tightly closed container.
PROTECTIVE COVERING
It is not customary to hide the veneer surface under a layer of opaque varnish. To show the structure of the wood, transparent coatings are used. The matte finish enhances the natural color of the wood and protects it.
Unprotected wood, such as the surface of furniture, soon becomes covered with water stains, scratches or traces of dirt. Therefore, it is advisable to apply a protective coating to everyday furniture, from which dirt can be easily removed.
The matte coating forms a protective layer on the surface of the wood, which is much harder and more durable than wax. A matte finish is less noticeable on wood than polish or clear varnish. However, if you apply too thick a layer of matte coating, you can get an unpleasant “greasy” sheen.
The matte coating penetrates the upper pores of the wood and changes the reflectivity of the surface. Its color becomes more intense and warm. When a matte finish is applied to untreated wood, experts say it begins to shine. With this processing method, the natural color of wood becomes more saturated.
COATING MATERIAL
1. Primer.
2. Matte finish.
3. Solvent.
TOOL
1. Grinding device.
3. Damp cloth.
5. Sandpaper with a block.
6. Wool fabric.
7. Old newspapers.
8. Brush or broom.
9. Tampons made of cotton wool, thin linen or cotton fabric.
10. Fine lattice brush.
SHELLAC AND CELLULOSE
There are two types of matte finish. One of them is shellac, the most important component of which is obtained from the secretion secreted by scale insects. It is cleaned, bleached and shaped into leaves. The matte finish obtained from shellac has a light yellow color. If they want to make very light wood matte, leaving the color unchanged, use bleached shellac (but only specialists can do this).
Another type of matte finish is cellulose. Today it is used much more widely than traditional shellac. Cellulose forms a strong layer and is more durable than shellac, making it primarily suitable for everyday furniture.
JUST DISSOLVE
Previously, carpenters and restorers themselves prepared compositions for matte surface coating. Today, ready-made formulations are increasingly used, which are diluted immediately before use.
The matte coating is applied with a swab. Unlike a brush, it fills the wood pores deeper with liquid. This creates a soft shine. The coating is applied in thin layers several times.
HOW TO STRENGTHEN YOUR PROTECTION
If you want to better protect the wood and increase shine at the same time, apply a second coat after the first coat has dried. If this is not enough, coat the surface a third time.
The cellulose coating can also be applied by brush. Since a large brush absorbs a volume of liquid approximately equal to a tennis ball, the surface finished in this way may appear streaky. Each new brush stroke is clearly visible. In such cases, the surface should be treated with a coil of thin steel wire.
STAIN PRE-TREATMENT
A tightly packed tampon absorbs liquid slowly. Therefore, it takes longer to wet it.
DOSED PRESSURE
A swab well soaked in liquid, from which the solution should not drip, is transferred to the surface of the wood. Too much pressure is just as harmful as too little pressure. Do not apply a large amount of matte coating, it is better to apply another layer after drying.
You only need to move the swab in the direction of the wood grain, stroke by stroke. Apply the matte coating evenly over the entire surface so that after the first layer has dried, a uniform matte sheen is visible on the wood.
The thinner the matte finish, the easier it is to work and the less shellac is applied to the wood. The solvent gives a slight shine after each swab on the wood.
The solvent evaporates and the wood becomes dull again. Therefore, you need to evaluate the resulting coating not immediately, but after it has dried. Only then can you see whether one layer is enough or whether a second or even a third layer needs to be applied.
If the matte finish appears streaky (the shine intensity is uneven), this can be corrected by treating it with a roll of fine steel wire (000 or 0000).
Wooden products almost always require leveling and sanding at some stage. During such work, all traces of glue, protruding pile, unevenness, chips and other defects must be removed from the wood. Typically, wood is sanded before applying an adhesive, protective or decorative material (primer, paint, varnish, etc.) to it.
The grinding process has many subtleties and pitfalls, which it wouldn’t hurt to know about in advance when doing work at home.
What and how to grind
The goal of sanding wood is to do it as quickly and efficiently as possible. effectively remove defects without leaving noticeable deep scratches. To do this, you can use special tools - now their price is not too high.
There are several types of grinding machines available for sale:
- tape;
- oscillatory;
- grinders (angle grinders);
- surface grinding;
- orbital.
You can install not only abrasive wheels on the grinder, but also brushes. Thus, nylon brushes are actively used for sanding wood. They allow you to make the surface not only smooth, but also highlight the texture of the wood by choosing softer fibers. This process is called brushing.
For large surfaces made of wood and wood-based materials (veneer, chipboard, fiberboard, plywood), belt and surface grinders are best suited.
Many people still prefer to sand decorative items, furniture, toys, frames by hand, and this is not such a bad method - it allows you to achieve a perfectly smooth surface effectively and without unnecessary expense. At least, when working with your own hands, you won’t have to think about where to get it (ask a neighbor, buy it in a store, rent it, leaving a deposit).
Belt type machine
Belt machines are so called because the sandpaper here is made in the format of a belt and it continuously moves thanks to rollers. This machine is designed for intermediate and rough sanding. But in order to achieve perfect smoothness and perfect finishing (this is especially true for those who make furniture), you will have to additionally use other sanding equipment.
There are different types of sandpaper you can install on your belt sander. And, for example, when inserting fine-grain sandpaper, it is quite possible to achieve a normal result for carpentry that is to be painted. And, say, to eliminate long scratches you will have to carry out step grinding, changing the grain size several times.
The belt sander has excellent performance. But it should be recognized that the tape is placed on it in such a way that not all points and grooves on the surface of the board can be properly processed.
Even with a considerable width of the belt, it grinds mainly at its center. The parts of the tape behind and in front are not used for this. They are in a slightly raised position, and their main function is to feed the driving roller mechanisms.
Another obvious drawback of belt equipment is its solid mass; it is quite difficult to perform any operations with such machines in weight when processing vertical products.
Belt machines for sanding wood also have a disadvantage, such as high noise - working without earplugs or headphones will not be very comfortable. And one more important point: if you leave the machine in one place for a long time while working, a fairly noticeable hole will appear.
Surface grinder
Even sanding large pieces of wood with a surface sander is quite fast. The key organ of the device is a flat, rather large plate (sole), to which the required abrasive is attached. This design is famous for the almost complete absence of dead zones (that is, areas that cannot be reached with a machine and processed tolerably) - any corners can be sanded relatively easily.
The demand for flat sanders among woodworkers is due to their reasonable price and availability of equipment. When choosing such a machine, you should pay attention to such parameters as motor power (usually we are talking about indicators in the range from 150 to 300 Watts), weight, amplitude and frequency of the sole stroke.
Manually
Sanding wood by hand, of course, requires a lot of labor and physical effort. But this method of grinding is a priori less aggressive and allows you to completely control the process. Even in hard-to-reach places - in corners and on complex curved bends - you can get decent quality grinding by choosing the manual method.
With the so-called interlayer grinding of finishing coatings, manual work has no alternatives at all - only it eliminates the risk of damage to the already applied finish. Manual processing (compared to sanding machines) allows you to get the most even and smooth surface, although it takes many times more time.
Pads and jaws
The block is an extremely useful device for manual grinding; its presence and correct use can speed up the process. The block, as a rule, is a regular wooden block wrapped in sandpaper. Its abrasive side should be on the outside, and the non-abrasive side should be attached to the block with a large stapler or PVA glue. Some hardware stores sell ready-made pads with sandpaper, that is, you don’t have to make it yourself, but just buy it.
Foamed polyurethane sponges are also used for sanding wood. They are more convenient to use than sandpaper, since you can wash them under water after work. Sponges and abrasive cloths are great for careful hand sanding of wood, allowing you to process the smallest details. They can also be used to sand primed or varnished wood.
Selection of sandpaper
What is the best way to sand wood? Which sandpapers should you choose for your work? In reality, these are not such simple questions. Sandpaper today is made from different materials:
- pomegranate (very rare);
- silicon carbide;
- ceramics;
- electrocorundum and others.
Garnet is characterized by the fact that it wears down faster than all other materials, but carefully sands wood. And silicon carbide, according to experts, is perfect for sanding the varnish coating and removing particles of debris and dust stuck to it.
Ceramic sandpaper is usually used when sanding wood with sanders. Skins with a ceramic working surface are one of the hardest and most expensive abrasives. Much the same can be said about corundum.
But the most important classification of sandpaper is the classification by grain size. At the moment, there are coarse-grained, medium-grained and fine-grained sandpapers.
In the Russian Federation, the marking of sanding products complies with the ISO-6344 standard - the grain size is indicated by the letter “P” and a number. The larger this number (it shows the exact number of sieve wires in one inch), the smaller the grain size. And, accordingly, the smoother the product becomes after sanding with such sandpaper. Typically this marking is indicated on the packaging.
It is advisable to buy several types of papers at once for sanding wood. Coarse-grain paper is considered to be paper that is marked with a number from 40 to 80; it is suitable for rough processing. The markings for medium-grained sandpaper contain numbers from 100 to 150, and the markings for fine-grained sandpaper contain numbers in the range from 180 to 220.
Note! You can find GOST markings with the letter M. It means fine-grained sandpaper.
In addition, sandpapers come in closed or open-grain types. The first ones are very densely covered with grain - that is, their abrasive is more effective and efficient. And on the basis of open-fill sandpaper there are significantly fewer grains (usually their share is no more than 60% of the entire surface of the canvas), so it is not so effective. But the presence of empty space between the grains prevents the sandpaper from quickly clogging - this prolongs its service life.
Thus, sandpapers with closed filling are suitable for hard surfaces, and with open sanding - for more pliable and soft ones.
Dry and wet sanding
To sand wood before and after applying finishing coatings, two current techniques are used - dry and wet.
Wet sanding involves applying liquid to the grainy surface of the sandpaper. Such a working fluid can be ordinary soap solution, white spirit and mineral oil.
During wet grinding, the abrasive becomes clogged much more slowly and, accordingly, its service life increases. But the wet method also involves the formation of an unpleasant mess of chips and foam. In this case, the home craftsman will have to periodically wipe the wooden product.
Rules for manual grinding
You should start your DIY sanding with the coarsest-grained sandpaper available to remove obvious defects from the surface of the wood. But here we must still take into account the nature of the damage that needs to be eliminated.
Having reached the edge of the surface to be treated, be sure to grind off the sharp corners. Soon, as a result of exposure to coarse abrasives, dust mounds will begin to appear on the wood. They should be carefully removed with a vacuum cleaner. Then you can proceed to processing with the next medium-grit sandpaper.
This processing is carried out according to the same principles as described above. The final stage is grinding with an abrasive with the finest grain. After this, the wooden product should become completely smooth, there should be no flaws left on it.
One of the most common methods of wood processing is sanding it using abrasives. Treated with sandpaper it becomes soft to the touch; there are several types of sandpaper, designated by numbers. The number determines the size of the abrasive particles applied with glue to the sandpaper. The paper with the smallest particles is called “nulevka”. The most “delicate” grades of sandpaper are rarely used for processing wood. This is explained by the fact that wood is a soft material and the pores of sandpaper quickly become clogged with its particles. Small abrasive particles quickly sink into wood dust and stop working. Therefore, we recommend using at least No. 10 sandpaper for basic work.
Sanding wood with sandpaper takes a lot of work. It will be easier for you to work if you understand why and how to do it. Before the invention of mechanical tools for sanding wood in the mid-19th century. There was practically no need to sand the wood. In fact, sandpaper was born only after the advent of mechanical tools. The wood was processed exclusively by hand, and such processing gave a completely smooth surface.
It is mechanical woodworking tools, which make carpentry work so much easier, that make us spend so much labor sanding woodwork before finishing it. Mechanical tools, regardless of their sharpness and precision of adjustment, leave marks on the wood that are clearly visible under the finishing film. To remove these marks, you need to spend a lot of time and effort sanding the wood. , which you have to pay for using the machines.
The purpose of sanding wood is to remove defects as quickly and efficiently as possible, without leaving deep scratches on the wood if possible. In practice, this usually means you start sanding with 80 or 100 grit sandpaper. However, there are times when it is better to use coarser paper or start sanding with 120 or 150 grit paper. To prepare wood for painting, writes Infobud, sandpaper with a grit of 100 units is suitable. Always sand wood along the grain, regardless of the grit of sandpaper you use. Sanding against the grain or at an angle can cause such damage to the wood that it takes a lot of effort to smooth out the imperfections.
Any power tools leave marks on the wood that should be removed with sandpaper. The waviness shown in the illustration is caused by a plane or jointer.
Whatever sandpaper you use to sand the wood, you will need to remove any scratches from the previous step in each step until you use 180-grit paper for the final step. There may be situations where you end up with 150 grit sandpaper, or you may decide to continue sanding the wood and end up with 220 grit paper. Until you have gained sufficient experience, use 180 grit paper for the last step of sanding wood.
In theory, it would be best to sand the wood sequentially with all grades of sandpaper up to 180-grit sandpaper, but most craftsmen “skip” grades. In other words, most craftsmen believe that fairly good results are obtained if wood is sanded in this order:
Use 80 grit paper first;
- then 120 units;
- finally, 180 grit, thus skipping sanding with 6 umaga grit 100 and 150 grit.
However, decisions of this kind are purely individual, since everyone, when sanding wood, presses the sandpaper differently and determines for themselves when it is worth changing the paper that has worn out during the work.
It's not easy to see what you've achieved through sanding. The secret is that the treated surface must be viewed from an oblique angle, while the light must fall on the treated surface perpendicularly. Then, in reflected light, you will be able to see defects or scratches from sandpaper that have not yet been sanded. If you sand a flat surface by hand, always use a sanding block that has a soft cork, rubber, or felt pad between the sandpaper and the wood.
Otherwise, the sandpaper, under the pressure of your fingers, will first “bite” into the softer wood fibers that appear in the wood in the spring. As a result, the surface will become slightly grooved, which you may not notice until it begins to shine after varnishing. You can make your own cork block for sanding wood, which will be convenient for you to work with. Glue a 3-4 mm thick cork pad - you can buy it at an auto parts store - onto a block of soft wood, rounded at the top edges.
 |
Disk;
- tape;
- eccentric.
Disc sanders are the cheapest and least efficient type of wood sanding tool. When using such machines, it is almost impossible to damage the wood, but they sand very slowly.
Belt wood sanding machines are more expensive and very effective at removing a significant layer of wood. But draw frames are difficult to operate. It is very difficult to sand wood with a belt machine without making gouges. It's even more risky to use a belt machine to process plywood: most likely, in some places the top layer of veneer will simply disappear.
 |
The three most common types of hand sanders are (from left to right): disc sander, belt sander, and random orbital sander.
Sandpaper
There are usually four types of sandpaper available commercially: two types are designed for initial sanding of wood, and two types are for sanding and finishing wood.
All four types of sandpaper are designated by grit level, which ranges from 36 to 2000 grit. The grain size is determined by the number of cells in 1 square. inch of sieve through which the abrasive material is sifted. The finer the cells, the larger the number indicating the grit and the smoother the sandpaper. The best grades of sandpaper for sanding wood are made from garnet and aluminum oxide abrasives.
Garnet sandpaper is usually orange in color. The abrasive grains split at sharp angles, and the garnet paper retains its functionality until it is completely worn out. Garnet sandpaper is the cheapest of all four types and is the most popular for hand work. Its grain size varies from 36 to 280 units.
Aluminum oxide sandpaper is usually reddish-brown. This abrasive is stronger than garnet, but when split it produces less sharp edges. Aluminum oxide sandpaper is more expensive than garnet sandpaper, but it lasts longer. Therefore, such paper is almost always used for sanding belts and discs, and is expensive. The grit size of aluminum oxide sandpaper varies from 36 to 280 grit.
The best sandpaper for finishing wood sanding is made with silicon carbide abrasives. There are two types of such sandpaper:
1. In black silicon carbide paper, the abrasive is glued to the paper backing with waterproof glue. This paper can be used with or without water-based or oil-based lubricants. You should almost always use this type of sandpaper with some kind of lubricant. Otherwise, it will soon become clogged, making sanding a very expensive procedure. The maximum grain size is 2000 units.
2. Gray silicon carbide sandpaper contains a soap-like lubricant that makes final sanding easier without the use of additional lubricant. This lubricant is zinc stearate, the same substance that is added to most varnish primers. Maximum grain size 400 units.
Black silicon carbide sandpaper is best used with a water or oil lubricant to sand wood surfaces after several coats have been applied and you are confident that you will not wear through the finish. It is best to sand the first and second layers of wood coating with gray silicon carbide paper. Even if you rub the coating in several places, the damage will not be too significant.
Exposed glue Glue that comes out at the joints of wooden parts or is left on the wood by dirty hands covers the surface of the wood and does not allow stain or varnish to penetrate inside. As a result, light, unsightly spots will remain on the product.When bonding edges, whether joining solid wood to solid wood or solid wood to plywood, escaping glue is a good sign; this means that you have applied enough glue and pressed the parts together firmly enough. However, excess glue must be removed, and then the wood must be sanded with sandpaper in the places where it protruded. There are two ways to remove glue from wood: wipe it off immediately with a damp cloth, or let it harden to the point where you can pry off a strip of it with a putty knife or blunt chisel. In both cases, you will need to sand these areas to remove any remaining adhesive that has soaked into the wood. If the glue hardens before you can remove it, you will have to scrape it off. This can damage the wood. Therefore, it is best to remove the glue before it has time to harden.
It is more difficult to deal with glue that has come out at the corners of perpendicular joints of wood (for example, between vertical and horizontal frame elements), since these places are difficult to sand. It is not easy to sand perpendicular joints without affecting the cross grain on one of the parts. Therefore, it is best to avoid any adhesive overhangs at all. In other words, do not apply more glue than is necessary for a strong connection.
If the glue does squeeze out of joints where the wood grains run perpendicular to each other, and you notice this before the glue hardens, wash it off with water. You will then have to sand the wood to remove any wood fluff that has been raised by the water. This can be done in two ways that do not leave scratches across the grain. Work the shorter piece first, lightly touching the cross piece. Then sand the cross piece to remove any scratches that may have appeared on it.
– cover the part with protective tape while you sand the connection part perpendicular to it. If the released glue dries before you discover it, there are two ways to remove it from the wood:
Either dissolve;
- or remove mechanically with sandpaper or scraping.
White and yellow glue can be dissolved with water. Hot water or water with added acid (such as vinegar) is more effective. Water, however, lifts the wood fibers, and the area where the stain was will absorb more water and darken. To get rid of the discoloration, you will have to re-sand the area, removing the water-damaged layer of wood, after the wood has dried. You can also use toluene and xylene to remove hardened white and yellow glue. These organic solvents soften the adhesive to the point that it can be removed with a stiff rag or soft-bristled brush without lifting the wood fibers.
One problem that may arise is that the stain acts as a lubricant for the sandpaper, so sanding the wood becomes less effective. And when you reapply the stain to the treated area, it may turn out lighter. If this happens, stain the entire piece (beam, leg, etc.) and then, while the piece is still wet, sand it with the same grit (or one less) that you used on the other pieces. .
Wipe off excess stain with a rag. If you still can't get an even color, apply paint remover and remove as much pigment as you can (paint remover also removes white and yellow glue). There is no need to remove all pigmentation from the wood. Then sand the entire surface with the same sandpaper you used in the final step and re-stain it. The stain should now apply evenly, unless the cause of the spotting lies in the wood itself.
Working with a file
Speaking about manual wood processing, it is impossible not to talk about rasps and files. These ancient instruments remain relevant now, in the era of technological progress. Files are used primarily for metal working, but large files such as the rasp and hog file are designed exclusively for woodworking. When processing wood, file movements should be made in one direction, since material scuffing may occur when moving in both directions.
In particular, this applies to working with multi-layer materials, such as plywood or veneered products. Do not try to apply as much force as possible when working with the file. Make rhythmic and easy movements. Files designed for metal work clog quite quickly and lose most of their abrasive properties. In order to prevent this, we recommend that you periodically clean the working surface of the file with a wire brush while working on wood (Fig. 4).
This will make your work easier and faster. To facilitate the rather monotonous and difficult work of sanding wood products, there are several electromechanical devices.
All photos from the article
This may seem strange to sophisticated people, but the question of how to sand wood is quite relevant. Therefore, it needs to be given due attention. We will provide you with all possible answers on the topic, and also show you a visual video in this article.
Different ways to sand wood
Classification of sandpaper and types of abrasive
Note. Basically, all sandpaper is classified by grit. That is, according to the grain size of the abrasive.
| Purpose | Marking (GOST 3647-80) | Marking (ISO-6344) | Grain number (µm) |
| Coarse paper | |||
Roughing |
80-N | P22 | 800-1000 |
| 63-N | P24 | 630-800 | |
| 50-N | P36 | 500-630 | |
|
Rough processing |
40-N | P40 | 400-500 |
| 32-N | P46 | 315-400 | |
| 25-N | P60 | 250-315 | |
|
Primary grinding |
20-N | P80 | 200-250 |
| 16-N | P90 | 160-200 | |
| 12-N | P100 | 125-160 | |
| 10-N | P120 | 100-125 | |
| Finish and paints | 8-N | P150 | 80-100 |
| 6-H | P180 | 63-80 | |
| Fine grain paper | |||
| Polishing and wet sanding for finishing | 5-N,M63 | P240 | 50-63 |
| 4-N,M50 | P280 | 40-50 | |
| For metal, plastic and ceramics | M40\N-3 | P400 | 28-40 |
| Finest grinding and polishing | M28\N-2 | P600 | 20-28 |
| M20\N-1 | P1000 | 14-20 | |
| M14 | P1200 | 10-14 | |
| M10/N-0 | P1500 | 7-10 | |
Marking and grit table
Electrocorundum:
- a charge of bauxite agglomerate, iron filings and carbonaceous material is melted in arc furnaces, from which electrocorundum abrasive is obtained;
- it has a high density and excellent cutting ability, but in some cases these properties are improved by adding alloying additives to the size, for example, chromium oxide (the abrasive in this case has a ruby color, as in the photo above);
- sandpaper with electrocorundum is produced most often.
Silicon carbide:
- to obtain abrasive in Acheson furnaces, graphite is sintered with silica, resulting in shiny crystals of irregular shape with sharp edges;
- Silicon corundum is convenient because during operation the crystals split and form new cutting edges. This property allows you to preserve the working surface for a long time, avoiding clogging.
Pomegranate:
- for sanding wood, garnet is the highest quality abrasive, despite its softness (6.5-7.5 Mohs);
- The paper wears out quite quickly, but due to the same grain sizes, sanding gives a smoother surface compared to other abrasives.
Diamond, elbor:
- Diamond has the highest hardness and elbor is slightly inferior to it in this regard, therefore, such abrasives can be called the best in the world;
- the problem is that the price of these minerals is too high, so they are rarely used for sandpaper.
Sanding methods
Note. For sanding wood, the instructions recommend the use of two main methods - manual and mechanical. But each of them has several options, which we will now discuss.
The most common method of sanding wood is by hand, and this is not surprising despite technological progress. The fact is that you often have to process fairly small, hard-to-reach or embossed surfaces that cannot be reached with various electrical devices.
For textured surfaces, of course, it is better not to use anything at all and hold the paper in your hand - the sandpaper on the wood will follow all the curves that you will feel with your fingers. This way the processing will be of the highest quality.
As a last resort, a piece of foam rubber is placed between the fingers and the paper - sensitivity, of course, decreases. But, nevertheless, such a device is capable of going around all contours, for example, on a baguette or baseboard, evenly sanding the surface.
For flat surfaces, an ordinary block is often used, wrapped with sandpaper. This way you get two flat planes - one being processed and the other acting, which leads to the greatest production efficiency.
And, of course, there is a special device for this, called a block. The sheet on it is simply tensioned using clamps that are located along the upper edges of the board - this device is shown in the top photo.
If it is intended to cover a large area, then in such cases you can use an angle grinder (angle grinder) - an angle grinder or a milling cutter, on which you put a special round (disc) attachment, where there is Velcro on the working side.
Then, sandpaper of the desired grit is applied to this disc. But such a device is effective for rough processing, for example, when sanding log or timber buildings.
Better finishing of the wood surface can be done using a belt sander, but it is intended exclusively for flat surfaces. For example, if you need to sand the floor with your own hands, then direct manual work is out of the question because the processing area is too large.
But the car will cope with this quite quickly. Narrow paper (specially produced for this purpose) of the required grain size is placed on the broaching mechanism - the sanding is of high quality.
Conclusion
We hope that you have understood how to sand wood correctly and all you have to do is select the desired paper grain size. But if you still have questions, you can ask our specialists in the comments section - we are ready to answer all questions.