As a rule, few people expect the moment when part of the ceiling suddenly decides to fall off. Some may be lucky enough to never have to deal with the question of how to repair cracks in the ceiling. Of course, fixing the hole as soon as possible is the very first thought that comes to mind, although few people actually know how to act in this situation.

Repairing cracks in the ceiling: solutions

The most popular and effective ways, as a rule, can be accessible not only to specialists or professionals; any ignorant beginner can find a sealing option that is within his capabilities.

Option #1

This option will appeal to those who do not want to sacrifice their energy and time, but want to get rid of the pressing problem as quickly as possible. So, most simple solution the problem of how to repair a crack in the ceiling is a banal disguise using ceiling tiles.

Carrying out calculations required quantity material occurs according to the following scheme:

• A reduced copy is drawn ceiling surface on any piece of paper.
• A grid is drawn, the side of a cell is equal to the length of the side of one panel.
• Based on the drawn diagram, the number of panels is calculated, taking into account all the details that need to be adjusted to the dimensions of the ceiling. In addition, you must also consider what you will need to purchase Additional materials, in case of unsuccessful circumcision.

Experts also advise installing the tiles on the cracks in such a way that the hole is located in the central part of the panel, otherwise it is almost impossible to guarantee the strength of the adhesion of the panel to the ceiling.

Of course, this method will not allow you to completely get rid of height differences, however, the use of ceiling tiles guarantees getting rid of cracks at minimal cost, and will also save time and effort.

Option No. 2

For those for whom simple camouflage is not suitable, we can recommend the option of direct repair. If the resulting crack is small, you can use the spot filling method, that is, getting rid of the crack locally, without repairing the entire ceiling surface.

You can also turn to this option when you plan to wallpaper the surface in the future. But in this case, it is necessary to take into account the thickness of the wallpaper, since thin wallpaper do not guarantee camouflage of putty areas. If the use of thin wallpaper is unavoidable, then you should paint the surface with water-based paint several times in order to give maximum uniformity to the entire ceiling surface.

So, sealing cracks in the ceiling is carried out in the following steps:

• We clean the cracks. Absolutely all irregularities should be removed from loosely attached parts.
• We prime all cracks, both inside and outside, using two layers of primer that ensures deep penetration.
• We dilute the putty mixture and carry out the repair itself by filling the cracks with the mixture and leveling it with a spatula along the entire perimeter as neatly and evenly as possible.
• We leave the ceiling for a day for the purpose completely dry.
• Sand the surface to be repaired until the unevenness is removed.
• We proceed to further finishing of the ceiling - painting, wallpapering or other types of decorative work.

It is also necessary to keep in mind that this kind of work is quite dirty, so preparatory work All furniture should be removed from the room being repaired, and the floor should also be covered with film. This will greatly facilitate the post-repair cleaning process.

The options described above are ideal for solving the problem of how to repair a crack in the ceiling, only if it is a small crack. In cases where the cracks are very deep or large, it is necessary to take a more careful approach to the repair process so that the result is a surface that is different good quality and durability (more details: " ").

How to repair a crack in the ceiling: fillers

Exists a large number of options and types of fillers that are ideal for filling cracks of various depths and widths.

How to repair a crack in the ceiling, watch the video:

PVA glue

In order to repair a crack in the ceiling using PVA glue, you need to cut any fabric into strips, and then place these strips tightly in the gap, which has been previously cleared of all loose elements.

The ceiling is always in sight, so its finishing is given Special attention, which is based on leveling it and whitewashing. The better the ceiling is whitened, the more clearly all sorts of defects appear on it, one of which is cracks.

Often no one is interested in how to repair a crack in the ceiling correctly; they simply cover it up, without even thinking about why it could have appeared.

The reasons for the appearance of defects may be different, as well as the method for eliminating them, so we will pay special attention to this issue.

Due to the reasons why the defect occurred, not only their number depends, but also the time it takes to finish. If you ignore the cause of the occurrence, then all the work done will be reduced to zero and your efforts will be wasted.

In order to identify the cause of the crack, it is necessary to examine the following points:

• how long the building has been in operation;
• where is the defect located?
• overlap;
• crack size “its width and depth”;
• speed of spread.

The fact is that after the object is commissioned, the foundation is still subject to shrinkage throughout the year. During this process, some movement of the slabs is possible, which is why cracks may appear in the joints of the walls. Therefore, it is recommended not to engage in major finishing work for about 2 years, but rather to monitor how cracks appear to ensure the reliability of the building.

The finish that is applied to concrete ceiling, can also crack, which is possible for the following reasons:

· temperature;

· vibration;

· wear of materials;

· humidity in the room.

In addition, the concrete itself from which the slabs are made may have defects that were not identified at the construction stage.

That is why premature finishing without identifying the causes of cracks can only hide a possible danger.

Because many people prefer to repair a crack in the ceiling with their own hands, this issue must be approached thoroughly, and therefore this issue will be considered in more detail.

On concrete floors, spider-web-shaped cracks are not uncommon. These cracks appear during the hardening process of concrete and are therefore called shrinkage cracks. The reasons for their appearance are as follows:

• possible increased content of cement in the solution or its deficiency;
• during hardening were not observed the necessary conditions;
• improper reinforcement of the material.

These cracks do not exceed 0.1 mm in width, which is why they are often called hairline cracks.

These cracks usually do not cause inconvenience or danger, but over time air and moisture penetrate through them to the reinforcement. Because of this, the reinforcing steel can oxidize, increasing in size. Because of this reaction, the reinforcement begins to put pressure on the concrete and a greater force occurs on the part where the concrete layer is smaller, which leads to further damage to the integrity of the concrete floor. And since the mesh of reinforcement is made under tension, a change even in one area can upset the balance, which leads not only to the destruction of the area with the defect, but also the structure as a whole.

To prevent hairline cracks from later leading to dangerous consequences, it is necessary to carefully seal them so that moisture cannot come into contact with the reinforcement. To do this, the overlap is treated protective coating, which penetrates into the smallest cracks and forms protective layer on the stove. For this purpose, acrylic mixtures with water based. They are used for both final finishing, and before staining.

This method can be used to protect reinforcement only if the cracks have not reached the reinforcement base. In cases where a violation of the integrity of the concrete layer has occurred and the corroded reinforcement remains without a protective layer, serious repair work is required, the size of which depends on the degree of damage. To seal such defects, special mixtures with cement base and the addition of silicas, polymers and others. The layer of their application can reach up to 30 mm. Or low-shrinkage cement mortars are used. They can be applied in layers up to 50 mm.

The required solution can be applied using additional reinforcement, which will only increase the strength of the repaired area.

Instructions for using solutions are always detailed on the packaging, and if you follow them, hairline cracks will not cause concern.

After the layer of material has been thoroughly dried, a layer of putty is applied on top, after which the final finishing material.

Cracks in the plaster layer

Cracks can only appear on top layer plaster without affecting the base of the ceiling.

You can easily repair them yourself, without resorting to special repair compounds and without spending a lot of money.

Before starting to whitewash the ceiling, it is necessary to repair all existing defects on the plastered layer. To do this, tap the plastered layer in the area where cracks appear with a special hammer. Places where the plaster has separated from the concrete layer must be cleaned down to the base. After cleaning, check for cracks using a spatula. If there are any, they must be removed.

The cleaned surface is primed either with a special solution with a latex base, or prepared independently aqueous solution.

To level the surface, it is best to use compounds similar in content and density to concrete floor.

The solution, prepared exactly according to the instructions, is applied to the surface in layers using a spatula. The next layer is applied only after the previous one has dried. If the unevenness in the coating is deep, then you can use reinforced mesh to level them with the surface.

Before finishing the floor with putty, you need to make sure that last layer the leveling mixture has completely dried, “this can be determined by the uniformity of color throughout the entire perimeter of the work.”

If, as a result of tapping, it was found that the plaster did not come off, then Finishing work take less time and effort. The defect that appears must be carefully expanded and thoroughly cleaned of dust and primed. The crack must be widened by no less than 5 mm, otherwise its cavity will not be completely filled and the crack will appear again. After expansion, the gap is carefully filled with putty throughout its entire depth and width, before further finishing of the ceiling. For finishing, it is best to use gypsum mixtures or mixtures and fumed cement. Whitewash over these layers will look better, even if it is of poor quality.

After shrinkage of the foundation has occurred, cracks may appear at the joints of the floors.

This can be caused by temperature or vibration, or other factors. The frequency with which cracks will appear depends on the quality of the builders’ work.

The answer to the question of how to seal a gap in the ceiling between the slabs may sound menacing, but it is quite possible to do it on our own.

In order for the finishing at the joints to last as long as possible, they are freed from the old construction waste using special tools. After which the cracks are treated with a stream of air and moistened with a spray bottle. After this, immediately, the joints are filled with polyurethane foam to more than half the recess, while the cylinder tube must be directed into the gap until it stops.

For this purpose, it is necessary to use only high-quality foam so that after hardening it is durable and low-porous.

After the foam hardens (this takes about a day), it is cut off using a stationery knife. It is necessary that the cut be deepened into the joint to a depth of 4 cm. Next, the surface of the seam is primed.

After this, the seams are leveled using cement mixture. And only after 48 hours, “sometimes 24 is enough,” the joints are leveled with putty either over the entire surface of the ceiling or in a specific area of ​​work.

Upon completion of the work, the ceiling is sanded and further painted or whitewashed.

Such cracks are often not even visible under ceiling plinth, however, this does not mean that they should be ignored. They must be eliminated, at a minimum, so that if the ceiling leaks, water does not pour down the walls.

Sealing such cracks is not difficult; in general, it is similar to eliminating cracks between slabs. That is, the joints expand and are removed from dust and residues building mixtures, after which they are wetted and filled with foam, according to the same principle as the gaps between the slabs were filled.

The distance at which the joints should be expanded directly depends on the width of the plinth that will be used in the future.

When sealing joints between the ceiling and the wall, it is not necessary to use polyurethane foam; rubber or silicone sealant. But before you seal the cracks, the surface must be primed.

The use of prepared PVA and cement mastic is also not prohibited. The composition should look like a paste and should not leak out of the gap. Here it is also necessary to prime the surface before sealing. This mastic is an excellent sealant.

After the foam or sealant has dried, the joint surface is leveled and covered with a latex solution in a 1 to 1 ratio with water.

Sometimes, when removing an old layer of plaster, cracks are found in the joints of ceilings. Sometimes this suggests that eliminating them requires a more serious approach than simple cosmetic finishing.

Such cracks are a signal that stress is weakening in this place due to external and internal influences on the slabs.

SNiP 2.03.01-84 stipulates and allows for a situation where identical cracks can appear in only one type of reinforced concrete structure.

In order to understand whether it is possible to seal cracks with your own hands, it is necessary to analyze the situation.

To begin with, it is necessary to answer that in addition to hairline cracks, there are other types of cracks:

• arising for technological reasons “temperature or small waves of vibration during the formation of the future slab, or disturbances in the tension of the reinforcement, causing further damage to the integrity of the structure” - technological;
• appeared as a result of transportation or installation, as well as during operation - deformation.

In rare cases, one of the above cracks appears in monolithic reinforced concrete structures"except for shrinkage." But if they do appear, and their width does not exceed 2 mm, then a simple sealing with cement mortar using a construction syringe is sufficient. This must be done so that the fittings are not damaged by moisture.

When such a crack expands, you cannot use power tools, you can only use hand tools.

On slabs that are completely or partially hollow, cracks appear much more often, and before starting to seal them, it is necessary to study them.

Longitudinal shallow cracks are quite acceptable, and they can be repaired with mortar.

Transverse cracks must be carefully examined and it is best to involve specialists for this, because in this situation it may be necessary complete replacement concrete block, which is impossible to do on your own.

To monitor how the crack is progressing, control beacons are used. They are made independently from paper or lintels from plaster. The date of its installation is indicated on or next to the beacon.

Having repaired all the small cracks, the ceiling must be primed, and then puttied and painted.

Troubles such as the formation of gaps between floor slabs on the ceiling, or simply the appearance of seams that were once not entirely successfully sealed, are very often found in panel high-rise buildings. Therefore, at the first signs of such phenomena, measures must be taken. And for this you need to have information on how to seal the seams between the panels on the ceiling yourself, without resorting to calling specialist finishers.

If the apartment is located on the last, top floor, and there is a gap in the ceiling between the slabs, then it is possible that it will soon begin to drip from it, which means that a persistent smell of dampness and stains of mold or mildew may appear in the rooms, and in addition , the heat will quickly leave the room. These circumstances are especially unpleasant during the cold months of the year. Therefore, in such a case, repairs must begin with an inspection of the roof, since if the defects are not dealt with roofing, then sealing the cracks from the inside and leveling the ceiling is wasted work.

If an inspection of the roof suggests that everything is in order with the roof, then you can safely begin repairing the ceiling. In the case when it is discovered that the waterproofing roofing material is damaged, then first you need to to take steps its repair, for example, replacing sheets of roofing felt, which are usually used to cover the roof in multi-storey buildings with a flat “soft” roof.

However, seams can crack not only on the upper floors, but also on any others. This is a common consequence home shrinkage processes.

So, having made sure that no external factors won't spoil it T labor-intensive work of sealing the seams of the ceiling, you can begin repair work inside the apartment.

Sealing the ceiling

If a small crack has formed between the plates, then you should start by widening it. It often happens that the process of cutting even a small crack or crevice suddenly opens up “large horizons” of work. Therefore, once we get around to this repair event, it needs to be done immediately conscientiously, in full, so as not to return to this issue for a long time.

If you want to solve two issues at once - sealing the seam and leveling the ceiling, you need to clean the entire seam from old concrete. Usually, this is not difficult to do, since when building houses, they use not very strong material for sealing joints. cement mortar.

Materials and tools

In order not to repeat the mistakes of the craftsmen who, when building a house, worked on the seams of the ceilings without due diligence, you need to purchase quality materials and all the tools necessary for work. You have to not just cover it up, but carefully open the seam and carefully seal it when sealing.

So, starting work you need to purchase:

1. The tools you will need are a medium, wide and narrow spatula, a spray bottle, a narrow metal brush, a wide brush, a container for mixing the solution, construction knife and a drill with a hammer drill.

2. You can seal cracks using different materials, and it’s worth listing everything that might be useful.

• Primer for concrete deep penetration— necessary for better adhesion of the surface and the material that will be used to seal the joint between the plates.

• NC, which is designed for sealing deep seams. This material tends to expand when hardening, tightly filling the entire space of seams and joints.

Cement "NTs" - perfect for sealing joints

• If you find a wide seam that requires sealing, you need to purchase dense insulation materials made from polyurethane or polyethylene foam. Polyurethane foam can be used instead.
• You will need latex elastic putty.
• Reinforcing is required. Its width will depend on the width of the seam - the tape should extend beyond its borders by 40 ÷ 50 mm on both sides.
• For final finishing you will need primary and finishing putty for the entire ceiling area.

Prices for mixtures for leveling walls and ceilings

Mixtures for leveling walls and ceilings

How to seal the seams between panels on the ceiling - we do it ourselves

Repairing the seams between the floor slabs will definitely entail putting the entire ceiling in order, so it’s worth starting with complete cleansing surfaces from paint, whitewash and possibly plaster.

• Using a spray bottle, the ceiling is sprayed with water. It is better to spray not the entire ceiling at once, but in parts. The well-moistened area is left for 10 ÷ 15 minutes to soak, and then the old coating is removed using wide and medium spatulas. After this, you can move on to the next section, where you need to carry out the entire procedure all over again. Such work is carried out until the entire surface of the ceiling is completely cleaned.
• Having removed all the old covering, the owner will immediately see the scope of the upcoming work. Usually there are two or three joints of floor slabs per room. Sometimes they are sealed very sloppily and appear as ugly humps. These bulges need to be eliminated and the ceiling made perfectly flat.

To do this, you need to take a hammer drill, install the desired nozzle on it, switch to impact mode without rotation, and step by step free the joint from the old frozen mortar.

The joint and the slab around it must be completely cleaned, and the gap itself must be recessed by at least 50 mm.

• Next you need to take a narrow iron brush or a wide brush and thoroughly clean the gap from dust and small pieces of concrete.

• The next step is to treat the crack with a primer in several layers, each of which must dry. The primer will strengthen the frozen solution remaining inside the joint, will not allow dampness and fungus to form in it, and will ensure good contact with the repair crew, which will be applied later.
• If the gap between the joints is wide enough and is more than 30 ÷ 35 mm, then you first need to fill it with polyurethane foam. It will adhere well to the primed surface and, expanding, will fill the entire opening.

As the foam hardens, it will come out of the seam, and when it is completely dry, it is carefully cut off so that at the junction of the slabs in the foam there is a groove, 30 ÷ 50 mm deep, tapering inward, like a triangle.

• If, during cleaning, a joint is found to be deep, but at the same time narrow, then you should proceed as follows.

Choosing a polyethylene foam seal required thickness, on him On the one side apply a strip of sealant and tuck it into the cleaned and primed joint using a spatula, leaving space to fill with concrete.

• Next, the joint is sealed with a solution of expanding concrete, but it is necessary to leave a small depression in the joint for the expansion of the solution and decorative plaster.

Sealing the seam concrete mortar"NC"

• After the solution has dried or prepared a groove in the dried polyurethane foam, an elastic latex-based material is applied to the joint. It is better to carry out the work using two spatulas - wide and medium or narrow. Use a wide spatula to scoop up the solution from a container, and use a narrow spatula to apply it to the joint between the plates, compacting it into the seam and leveling it to the level of the ceiling surface, while simultaneously removing excess putty.

• After 2 hours, which will be required for drying, they begin to reinforce the seams. To do this, apply with a spatula to the seam and the ceiling next to it in a strip of 50 ÷ 60 mm. thin layer putty, fix the serpyanka mesh on it, pressing it into the solution and removing its excess with a spatula.

• After the seams have dried, the entire ceiling is treated with a primer, applying it using a roller. It is better to cover the surface with two layers of the composition.
• When the ceiling is dry, you can start painting it. First, a thin layer of primary plaster is applied, and after it dries, a finishing smooth layer is applied. It is applied with a wide spatula and at the same time leveled to perfection.

Finishing- puttying the ceiling

• After the finishing layer has dried, you can apply paint, whitewash or wallpaper to the ceiling.

Video: repairing seams between floor slabs

Seal a hole in the ceiling

Sometimes it happens that when cleaning a seam from old mortar, not just a narrow gap opens, but big hole– defect of the floor slab. In this case, this hole can be sealed in two ways.

Sometimes such a “surprise” may appear on the ceiling when cutting seams.

In any case, the first thing to do is to thoroughly clean the inside of the resulting hole. This process is best done with a narrow brush.

1. Having freed the inside of the hole from dirt, it should be well sprayed with primer. After waiting for the first layer to dry, you need to apply the second.

• Next, the hole is filled with foam.
• Then, after it dries and expands, the excess is cut off, and a cone is cut out from inside the hole, at the base the size of the hole and 40 ÷ 50 mm high.
• This cutout is necessary to secure the cement mortar in it, which is applied next step. It is leveled with a spatula and left until completely dry.
• Then putty is applied to the place where there was a hole and around it 50-70 mm, and a sickle mesh is glued onto it, which is pressed into the applied layer of mortar, smoothed out and left to dry.
• Further work proceeds in the same way as when sealing seams.

2. Another method of sealing differs from the first, and it is used if a large void is found in the ceiling.

• In this case, you will need a piece of plywood (you can use laminate scraps) approximately 100 mm larger than the dimensions of the hole.
• Then, it is necessary to strengthen a wire grid in the hole, which must be secured to the sealant or cement mortar inside the hole. After the solution has dried, the wire must be securely fastened inside the opening. The grid will serve as a reinforcement for the repair mortar, with which they will create a unique stove.

Sealing a volumetric hole in ceiling- approximate diagram

• The mixed concrete is laid out on the prepared plywood; it should be uniform and not overly thick.
• The plywood platform with the solution is lifted and pressed tightly against the hole so that the solution completely fills the remaining cavity. We will have to come up with a reliable support for this kind of formwork that will hold it until the repair composition dries completely. A thick branch, a block or a pyramid of a table and chairs is suitable for this.
• After the solution dries in the opening, you will get a perfectly flat ceiling surface.
• Next, you can begin work on tidying up the entire surface of the ceiling.

Video: sealing a volumetric hole in a floor slab

It should be noted that it is quite possible to update the joint between the plates yourself. But the complete job is quite a complex job, so it is better to entrust it to an experienced finishing craftsman. However, if you have the desire and confidence in your abilities, this is a completely doable task.

A nuisance in the form of cracks in the ceiling can appear unexpectedly, or it can poison the life of the apartment owners for a long time, depressing them with its constantly growing appearance. Of course, the thought of getting rid of them as quickly as possible immediately comes to mind, but how to repair cracks on the surface of the ceiling is not always known.

Method one

This method is suitable for those who are not ready to spend time and effort on sealing cracks, especially if they are not large. In this case, they can simply be disguised. Ceiling tiles are excellent for these purposes.

• Draw a ceiling plan to a certain scale.
• Then line it with a grid with the side of the cell, equal to length sides of the tile.
• Based on the resulting diagram, calculate the number of tiles, including those of partial size. You will need to buy a little more, since the tiles that you have to cut may be damaged at first.

Advice! When gluing the tiles, make sure that cracks and differences in ceiling height do not occur at the joints between the tiles. Otherwise, you won’t be able to glue the tiles firmly..

Of course, neither mother-in-law nor elevation changes will go away. But the tiles will reliably hide all defects, while you will spend a minimum of money and effort on repairs and will no longer worry about how to remove cracks in the ceiling.

Method two

If you are not satisfied with masking the flaws, you will have to carry out repairs. How to repair cracks in the ceiling after many years of service? In cases where the depth of the cracks is small, and the number of cracks themselves is also small, you can resort to spot puttying. This means that the ceiling will be plastered only in problem areas(cm. ).

Spot putty can also be used in cases where the ceiling will subsequently be covered with wallpaper. But the wallpaper should be thick, since putty areas can be visible through thin wallpaper. If the wallpaper is still thin, then the ceiling after puttying must be painted light water-based paint in several layers, achieving uniform color of the entire ceiling.

Putty technology:

1. Cleaning cracks. All cracks must be cleaned of all flaking and crumbling particles and fragments.
2. The entire surface of the cracks and adjacent areas should be carefully primed in one or two layers with a deep penetration primer.
3. Prepare a putty solution and repair cracks in the ceiling, filling the recesses with putty and leveling with a spatula along the surface as evenly as possible.
4. Allow the putty to dry overnight.
5. Sand the putty cracks until smooth.
6. Now the ceiling is ready for finishing - painting, wallpapering, and so on.

Advice! Repairing cracks in the ceiling is enough dirty job. Before starting repairs, if possible, empty the room of furniture and cover the floor with film. Then clean up after finishing work will take place much faster.

Method three

The first two methods are good for getting rid of small cracks, but sometimes you have to deal with very deep and large cracks. In this case, you need to know how to repair cracks in the ceiling so that the structure retains its strength for a long time.

Methods for sealing cracks

When the depth of the crack is great, there is only one way out: fill it with filler. And there are several possibilities here. You can choose one of several common materials as a crack filler.

1. Using PVA glue

Since ancient times, it has been known how to repair a crack in the ceiling using improvised means. For example, pieces of fabric:

• The fabric was cut into strips and placed in the crack, which had previously been cleared of all crumbling particles.
• A separate piece of fabric with an area larger than the crack itself and ten centimeters wider than it was glued over the crack and the tissue embedded in it.

Today, PVA glue can be used as a suitable glue for these purposes. A crack in the ceiling after repair in this way will be reliably hidden with a layer of putty and will retain its strength for a long time.

Advice! Painting mesh, which has great strength and wear resistance, is an excellent material for sealing cracks.

1. Using sealant

Even a deep crack can be repaired using a special sealant. Sealants for a wide variety of purposes are available on the market. And you should consult the seller to choose the sealant that is best suited for your specific case. So, the composition matters building materials ceiling, as well as indoor humidity. Fill the crack with sealant until it is completely filled, level the surface with a brush or spatula, and after hardening, cut off the excess with a sharp tool.

Prevention of cracks

You should also consider the possibility of cracks appearing at the junctions of walls and ceilings and arched openings. If there are already cracks in the ceiling, then there is a high probability that cracks will appear in these critical places in the future.

Prevention can be done using serpyanka.

• It is important to thoroughly putty all surfaces before gluing it. This is done in order to avoid the appearance of bubbles in the future.
• Serpyanka is glued onto the putty surface, which, after drying, is also puttied.
• This method of processing corners and joints has proven itself in practice and allows you to forget about ceiling repairs for a long time.

Advice! Cracks in the ceiling may indicate leaks in the sewer system, shrinkage of the building, or damage to the strength of the ceilings. Fixing one crack will not prevent new ones from appearing if the cause of their appearance is not eliminated.. If you find a crack, consult a specialist to determine the cause of its appearance.