More recently, foil covering has been the most commonly used greenhouse design. But today it is being replaced by glass and polycarbonate coatings, which surpass the film in their properties, but they cannot boast of a low cost. If desired, it is possible to get products from the garden and under the greenhouse film covering, which will require the ability to choose a film, because one film differs from another in many ways. Manufacturers offer both the most basic types, such as plain polyethylene film, as well as advanced reinforced, polyvinyl chloride and stabilized coatings. Moreover, some sellers almost try to pass off cheap types of materials for their expensive counterparts, for the reason that the appearance of some types is very similar..
With a huge range of types of cover films for greenhouses, the question involuntarily arises – how to distinguish high-quality material from low-quality.
To solve the problem, you will need to take into account a number of factors:
- low prices;
- whether the material is practical;
- is he reliable;
- Does it provide high quality protection from ultraviolet radiation.
There are also marketers who are inclined to keep silent about the shortcomings of a particular film and unscrupulous employees of retail chains who seek to foist low-quality goods on ignorant buyers. So you need to understand at least a little about the characteristics of materials. We invite you to get acquainted with the types and characteristics of films.
Polyethylene film is used in the cultivation of greenhouse crops, and in construction work, and in the packaging of various goods. I must say that each roll of film can be used to cover the greenhouse industry. For example, at first glance, a strong film made from low-pressure polyethylene is low-strength and cannot withstand a temperature jump and radiation from the sun. It undergoes deformation and tear in just a couple of months in the summer, and is guaranteed to crack if the temperature drops to -15C in winter cold.
Varieties and characteristics
Usually, film coatings are distinguished according to many criteria:
- polyethylene (the most common and inexpensive);
- polyvinyl chloride;
- light stabilized;
- light scattering;
- double layer and so on.
Let’s consider some of the types of film and their more detailed characteristics..
Polyethylene film coating
One of the main advantages of this coating is its relatively low price. Such a film coating can transmit up to 80 percent of the heat in both directions and, for this reason, does not very effectively maintain the temperature gained during the day. With proper installation, a high-quality polyethylene film coating will last one summer, but in winter it will have to be dismantled due to temperature changes when winds and a snow layer destroy the film.
The polyethylene coating is quite easily damaged by literally anything, for this reason, the transportation and installation of such material must be carried out with a high degree of accuracy, since the increase in the smallest damage occurs at a high rate of “growth”, this will greatly slow down the process of arranging the greenhouse. The film is sold in rolls in a width of 1-3.5 m, it can be single-layer or in the form of a sleeve.
When working with the second option, the film is cut from the side and a wide single-layer version is obtained. As a variety, the greenhouse is covered with a film without cutting the sleeve, which, however, will not bring a significant increase in the service life. It is not for nothing that the bends of the sleeves are considered to collapse almost immediately, for this reason, such places are strengthened from the very beginning with the help of scotch tape..
The reinforced film coating differs from the usual polyethylene coating with a peculiar frame, which is usually made of fiberglass. The coating is made by pressing, twisting, stretching the material. The standard thickness of the gimp is from 0.3 to 0.35 mm. The polyethylene base turned out to be the most durable during operation so that it can withstand the radiation of the sun, additives are sometimes included in it. The main loads fall on the frame structures, for this reason greenhouses with such films are resistant to wind, snow layers and hail. The film coating protects the greenhouse if the temperature drops for a short time down to five degrees below zero.
The coating can last up to three years, however, some manufacturing companies set the time period up to seven-year periods.. Here the requirements are dictated by the climatic conditions of the regions and the technical characteristics of the film. Film shelters with reinforcement are highly maintainable: the holes are sealed with adhesive tape, no widespread damage occurs. The main characteristic of the film is not called its thickness, but how dense it is. The most popular film has a density of 115-210g / m2. Today, they sell covers that have pores that provide the greenhouse with moisture impermeability and at the same time do not allow the presence of “conservation” of oxygen inside.
The degree of reliability and strength characteristics of the reinforced film also has “reverse sides of the coin” – the material has a relatively high price. Another unpleasant feature is the relatively low degree of light transmission compared to the standard stabilized coating. And dirt (due to the relief of the material) is difficult to wash off, which does not add transparency to such a coating.
Polyvinyl chloride (PVC) film
One of the optimal coatings for greenhouse construction. It is an elastic and durable material that can be used for 2-5 years, depending on the climate. It contains impurities (yellow, transparent, green, blue, black, colored, etc.), which have light-converting and stabilizing characteristics..
This film can:
- let in almost the entire spectrum of sunlight (95%);
- pass almost all ultraviolet rays (85%);
- delay the harmful infrared spectrum (96%).
All this leads to the result that at night and with possible frosts in such a greenhouse a higher temperature regime will be established than in greenhouses with a polyethylene coating of the same volume and shape, which will be a significant advantage of such a film.
There are also disadvantages of PVC film.
- High cost, twice that of polyethylene. Although, given the fact that there is no need to seasonally purchase new coverage and engage in construction, such a high cost cannot be called an overly significant factor..
- Polyvinyl chloride film is able to attract dry particles from the air, although it is not at all difficult to wash off such dust.
- The material is relatively not frost-resistant, if the temperature drops to minus 12-17 C, the film will turn into an overly fragile state, for this reason, the presence of heating for a winter greenhouse from such material is mandatory.
With the introduction of special agents into ordinary polyethylene mass, the quality of its operation can be improved to some extent..
- Stabilized film coatings are made with the addition of impurities that increase the properties of resistance to sunlight. The operating time is doubled or tripled, but the price also rises. Such material can be orange or pinkish. With the same appearance, stabilized and ordinary polyethylene coatings are very similar and when buying, you need to study their packaging with markings.
- Light-converting film coatings are capable of converting hard ultraviolet radiation, which is harmful to greenhouse inhabitants, into red and infrared spectra, which increase yields. The above is due to phosphor additives, although it should be borne in mind that for a long service life of the material, some stabilizing substance must be included in the composition. In order to be confident in the store in choosing the correct light-converting film coating, you will have to organize its lumen using a UV lamp and make sure that the color of the rays changes to red.
- Heat-retaining film coatings are distinguished by the presence of a matte whitish shade. They have a weak transmission capacity to thermal radiation, for this reason the temperature level in the greenhouse will be a couple of degrees warmer than a similar one, but covered with other types of coatings. This feature can serve to increase early harvests to 25, as savings in heating costs will affect. The service life of such a coating is up to 3⁄4 years, if the coating has antistatic and hydrophilic characteristics..
- Stabilized hydrophilic the film coating makes it possible to solve the problems of “droplets” that are inherent to other substances. On the surface of such a film, there is a condensation of “flat-drop” forms in continuous layers, so there is no negative effect on the landings. The degree of light transmission contributes to a high heat transmission (up to 40%), for this reason, a rather high temperature level is constantly spontaneously maintained in such a greenhouse.
- Bubbly film covers are very similar to those in which fragile goods are packed. They have excellent light transmission and their heat insulation level is comparable to that of polycarbonate. Their degree of strength is low, if you do not take into account special types, although it is suitable for growing plants in small greenhouses.
- Foamed thick film coatings contain monolithic and foamed layers of polyethylene film that transmits light (up to 70%), perfectly keep the temperature, are suitable for building a greenhouse, which is intended for vegetation.
- Copolymer ethylene vinyl acetate coatings have decent strength characteristics, keep temperatures well, they are resistant to damage, wind load, low temperatures, and are hydrophilic. They have a high degree of light transmission (90%), but in the summer heat, overheating of the plants can be allowed. Service life – three years.
- Photodestructible film coatings are capable of deteriorating after a while (from three weeks to two months). They are used for greenhouses that do not have frame supports and for mulching. Many specialists recommend replacing the film after 36 months, as it tends to cloud and transmit less light. There are film coatings where more added substances were used in the production process, which is probably the best option..
In accordance with GOST, stabilized film for greenhouses or greenhouses is marked “ST”, light-stabilized film – marked “SIK”. A film marked “H” is also used – this means a stabilized or unstabilized coating for packaging household products.
The density and thickness factors of the film coating directly depend on how negative factors will affect it. If for ordinary polyethylene film the layer thickness has practically no effect on the service life, then if they mean stabilized materials, this means a lot. At first glance, a film thickness of 200 micrometers from 100 is almost impossible to distinguish. This is the reason for the scam of a number of unscrupulous sellers. In order not to become a victim of them, it is necessary to take into account the greater weight of the film of greater thickness, that is, the mass of a running meter of the film coating with a thickness of 200 microns is 530g, (150 microns = 400g, 120 microns = 320g, 100 microns = 260g and 80 microns = 210g ). Greenhouses are more suitable for a film from 150 to 200 microns thick.
It is preferable to choose a transparent material that can pass a large amount of solar radiation. To obtain such a coating of different shades, dyes are always introduced, which lose their color under the rays of the sun, which has no logic. With the durability of the dye, light enters the greenhouse in smaller quantities and the yield will decrease, therefore, it will be necessary to organize an additional lighting system. The colors of the films indicate a useful characteristic, which allows plants to assimilate the most favorable rays of the sun spectrum..
Any color additive is a spectrum mixer:
- lightproof mulching black – greenhouse cover;
- greenhouse blue and blue has good anti-condensation properties and mixes with the soil in 120 days;
- pink three-layer – translucent and durable, will last up to 5-6 years;
- black and white will keep you from sunburn.
If the buyer has chosen a standard polyethylene coating, here he minimizes the risk of receiving a low-quality product. Most of the “fakes” can be found when buying in the categories of coatings in high price segments. One way or another, it is preferable to purchase goods from trusted manufacturers and carefully monitor the accompanying documentation and labeling. China, Hungarian, Korean, Chinese, Israeli, Turkish products are represented on the market, film coatings from the following manufacturers provide fairly high quality.
- NPF “Shar” – made in Russia, this is a company that was founded in the early nineties and specializes in the development of polymer composites. In order for agricultural production to use various films, domestic inventions are being developed, and all materials are provided with durability, and some, as manufacturers say, can last about 8 years.
- “Agrokhoztorg” is a leading domestic polymer producer. Its offer is varied, including a reinforced greenhouse film called Vural Plastik..
- “Agrotema A” one of the domestic enterprises on the market since the beginning of the 90s. The main activity is the production of polyethylene films used in various fields. For arranging greenhouses, the company offers conventional polyethylene and reinforced films.
- “Stable” – a company that produces the film of the same name. In its production, the patented Fitistab additive is used, which imparts durability. It becomes suitable to apply the film year-round in almost any climatic zone. The company manufactures various types of film coatings that differ in thickness and characteristics, but are invariably highly reliable. These coatings are also sold in neighboring countries..
- “Odysseus” has been on the market since the mid-2000s. The company specializes in the production of polyethylene. For greenhouses, this manufacturer offers ordinary polyethylene and reinforced film with various thicknesses and widths of the canvas..
- “Polymer” – an enterprise from Kemerovo with thirty years of experience in the manufacture of film coatings. Coverings for greenhouses of this manufacturer are considered the best in Russia, they are offered in a wide range, which is periodically replenished with new products..
- “OPA” – a manufacturing company from St. Petersburg, which is equipped with modern imported facilities, producing films of various types, for example, high-quality coatings such as “Svetlitsa” “Polisvetana” or “Antiplesen” at quite reasonable prices.
- Richel Serres de France – a manufacturer from France, offering a comprehensive solution for the arrangement of greenhouses. Its official dealer in Russia is Greenhouse Technologies, offering Richel coating. It, in accordance with the reviews, can hold when applied in winter conditions for a long time..
Which one to choose?
When choosing a film, today the buyer is offered a wide range of analogs of the film that are more advanced in their characteristics and quality, which has traditionally been the most common material for greenhouses. It is worth mentioning some of their advantages and disadvantages..
The main advantages are as follows.
- Not very expensive. Different types of films have a difference in cost, but compared to materials such as glass or polycarbonate, film is in any case a more budget option..
- High characteristics in terms of elasticity and plasticity, for these reasons, with its help, a greenhouse of any design can be easily equipped.
- Resistant to water penetration.
- High levels of sunlight scattering transparency.
- Relatively low weight and easy installation.
There are also disadvantages.
- Short-lived. When choosing a plastic film, you need to know that it will have to be changed seasonally, unless its substitute can last a little longer.
- Unstable to sunlight. This quickly destroys it, although some films do not have such a pronounced drawback..
- Condensed moisture that builds up on the floor can harm many plants that are grown in greenhouses. This feature was partially got rid of by the invention of a hydrophilic film, which is made using special additives..
- Builds up an electrostatic charge that attracts dust and dirt, which reduces the transparency of the film. To a certain extent, it was possible to overcome this by introducing special additives..
- Many summer residents do not like the sagging of the film coating and its ability to stretch.
In any case, these rather significant disadvantages do not make the film less popular, since it is the cheapest way to build a greenhouse / greenhouse, and it may be more profitable to change the film annually than to spend a lot of money on expensive polycarbonate..
It is also worth figuring out how to properly solder, glue, sew, connect, cover, fasten, solder, glue, pull the film onto the frame.
Reinforcing frames are made of various materials:
- specially processed polyethylene (twisted, stretched, monofilament);
Fiberglass frames are very rare in our latitudes, they are almost never used. The process of building a greenhouse usually follows a standard scheme: components are selected, a supporting structure / frame made of wood or metal is installed, on which the selected material is pulled. Note that the parts, joints and the assembly of the frame itself, as well as the fastening of the covering material, are critical operations that must be performed according to the technology.
It is preferable to construct a wooden frame from coniferous wood, impregnated with any organic compound in order to prevent the appearance of rot, fungus, damage from insects. Each part must be properly planed, there should be no burrs on them, it is preferable if there is a chamfer along the edge. Each connection must be glued or attached in a different way, recessed into the structure, in order to prevent the possibility of breakthroughs of the covering material.
Any metal frame structure will necessarily be heated from the sun, so that the shelter does not undergo deformation, it is recommended to provide on each guide gaskets made of a wooden strip, self-adhesive tape, a plastic panel of small thickness. The use of double-sided adhesive tape will be a reliable barrier against overheating of the metal structure. Scotch tape helps prevent deformation and in addition fixes the covering material to the frame structure.
IMPORTANT! Greenhouses covered with films are optimally installed using frames made of plastic or aluminum, which are most suitable for the coating.
The required area of covering material should be calculated in accordance with the size of the greenhouse / greenhouse. It should be taken into account when calculating that the film in rolls should be laid with an overlap of 120-260 mm at each joint. In order not to be mistaken and not to get a shortage at the end, it is advised to add up to 15% to the total surface area of the greenhouse. When cutting the material to size, it is advised to cut out each end piece, adding up to 260 mm for each fastener. To fix, you can use a 20 x 35mm wooden lath.
The fixation of the material occurs:
- wooden stripes;
- strips from pieces of used flooring;
- laces, twine;
- packaging tapes;
- networks with large meshes – this is an ideal option if the cottage is located in a windy region;
- clips – galvanized guide rails up to 3000 mm long, which are previously attached to the frame structure, film coatings are placed on the clip, which are fixed with plastic inserts.
Advice. A collapsible clip can be made by hand using plastic pipes of various diameters.
As a rule, they first carry out installation operations on the main parts of the structure and only after that the film is fixed on the end parts of the greenhouse. The remaining parts of the coating are sprinkled with soil at the bottom to avoid their gusts..
To extend the life of a greenhouse covering material, you should adhere to the following simple rules:
- stretch the film or other covering material only if the temperature is within +12 +21 C, in calm weather, which partially eliminates the possible appearance of sagging of the film;
- it is recommended to cover greenhouses with annual material 1-4 days before the first planting of plants;
- do not recommend using clips, self-tapping screws, nails, wire in order to avoid damage to the film.
Even taking into account the fact that the film shelter is not very durable and durable when arranging greenhouses, if you correctly approach its purchase, the gardener has a good opportunity to spend minimal money and at the same time arrange a greenhouse / greenhouse in accordance with all the rules. As a result, a good harvest will not be long in coming..
For information on which film to choose for the greenhouse, see the next video..