Design, technical parameters and types of incandescent lamps. how LED lights are made how light bulbs are made

The incandescent lamp is the first electric lighting device that plays important role in human life. It allows people to go about their business regardless of the time of day.

Compared with other light sources, such a device is characterized by a simple design. The light flux is emitted by a tungsten filament located inside a glass bulb, the cavity of which is filled with a deep vacuum. In the future, to increase durability, instead of vacuum, special gases began to be pumped into the flask - this is how halogen lamps appeared. Tungsten is a heat-resistant material with a high melting point. This is very important, because in order for a person to see the glow, the thread must be very hot due to the current passing through it.

History of creation

Interestingly, the first lamps did not use tungsten, but a number of other materials, including paper, graphite, and bamboo. Therefore, despite the fact that all the laurels for the invention and improvement of the incandescent lamp belong to Edison and Lodygin, it is wrong to attribute all the merits only to them.

We will not write about the failures of individual scientists, but we will give the main directions in which the men of that time made efforts:

1. Search the best material for the filament. It was necessary to find a material that was both resistant to fire and characterized by high resistance. The first thread was created from bamboo fibers, which were covered with a thin layer of graphite. Bamboo acted as an insulator, graphite - a conductive medium. Since the layer was small, the resistance increased significantly (as required). Everything would be fine, but the woody basis of coal led to rapid ignition.
2. Next, the researchers thought about how to create conditions for the strictest vacuum, because oxygen is an important element for the combustion process.
3. After that, it was necessary to create detachable and contact components of the electrical circuit. The task was complicated due to the use of a layer of graphite, which is characterized by high resistance, so scientists had to use precious metals - platinum and silver. This increased the conductivity of the current, but the cost of the product was too high.
4. It is noteworthy that the thread of the Edison base is still used today - marking E27. The first ways to create a contact included soldering, but in this situation, it would be difficult to talk about quick-change light bulbs today. And with strong heating, such compounds would quickly disintegrate.

Nowadays, the popularity of such lamps is falling exponentially. In 2003, the amplitude of the supply voltage was increased by 5% in Russia, by today this parameter is already 10%. This led to a reduction in the life of the incandescent lamp by 4 times. On the other hand, if you return the voltage to an equivalent value down, then the output of the luminous flux will be significantly reduced - up to 40%.

Remember training course- even at school, a physics teacher set up experiments, demonstrating how the glow of a lamp increases with an increase in the current supplied to a tungsten filament. The higher the current strength, the stronger the emission of radiation and more heat.

Operating principle

The principle of operation of the lamp is based on the strong heating of the filament due to the electric current passing through it. In order for a solid-state material to begin to emit a red glow, its temperature must reach 570 degrees. Celsius. The radiation will be pleasing to the human eye only if this parameter is increased by 3–4 times.

Few materials are characterized by such refractoriness. Due to available pricing policy the choice was made in favor of tungsten, whose melting point is 3400 degrees. Celsius. To increase the area of ​​light emission, the tungsten filament is twisted into a spiral. During operation, it can heat up to 2800 degrees. Celsius. The color temperature of such radiation is 2000-3000 K, which gives a yellowish spectrum - incomparable with daylight, but at the same time not having a negative effect on the visual organs.

Once in the air, tungsten quickly oxidizes and breaks down. As mentioned above, instead of a vacuum, a glass bulb can be filled with gases. It's about about inert nitrogen, argon or krypton. This allowed not only to increase durability, but also to increase the strength of the glow. The service life is affected by the fact that the gas pressure prevents the evaporation of the tungsten filament due to the high glow temperature.

Structure

A conventional lamp consists of the following structural elements:

• flask;
• vacuum or inert gas pumped into it;
• filament;
• electrodes - current leads;
• hooks needed to hold the filament;
• leg;
• fuse;
• base, consisting of a housing, an insulator and a contact on the bottom.

In addition to the standard versions of conductor, glass vessel and leads, there are lamps special purpose. Instead of a base, they use other holders or add an additional flask.

The fuse is usually made from an alloy of ferrite and nickel and is placed in a gap on one of the current leads. Often it is located in the leg. Its main purpose is to protect the flask from destruction in the event of a filament break. This is due to the fact that in the event of its breakage, an electric arc is formed, leading to the melting of the conductor residues that fall on the glass bulb. Due to the high temperature, it may explode and cause a fire. However, for many years they proved the low efficiency of fuses, so they began to be used less frequently.

Flask

The glass vessel is used to protect the filament from oxidation and destruction. The overall dimensions of the flask are selected depending on the rate of deposition of the material from which the conductor is made.

Gas medium

If earlier all incandescent lamps, without exception, were filled with vacuum, today this approach is used only for low-power light sources. More powerful devices are filled with an inert gas. Molar mass gas affects the heat radiation of the filament.

Halogens are pumped into the flask of halogen lamps. The substance with which the filament is covered begins to evaporate and interact with the halogens located inside the vessel. As a result of the reaction, compounds are formed that decompose again and the substance returns to the surface of the thread again. Thanks to this, it became possible to increase the temperature of the conductor, increasing the efficiency and service life of the product. Also, this approach made it possible to make the flasks more compact. The disadvantage of the design is associated with the initially low resistance of the conductor when an electric current is applied.

Filament

The shape of the filament can be different - the choice in favor of one or the other is associated with the specifics of the light bulb. Often they use a thread with a circular cross section, twisted into a spiral, much less often - tape conductors.

A modern incandescent lamp is powered by a tungsten or osmium-tungsten alloy filament. Instead of ordinary spirals, double and triple spirals can be twisted, which is made possible by repeated twisting. The latter leads to a decrease in thermal radiation and an increase in efficiency.

Specifications

It is interesting to observe the dependence of light energy and lamp power. The changes are not linear - up to 75 W, the luminous efficiency increases, when exceeded, it decreases.

One of the advantages of such light sources is uniform illumination, since light is emitted with the same intensity in almost all directions.

Another advantage is associated with the pulsation of light, which, at certain values, leads to significant eye fatigue. The normal value is considered to be a pulsation coefficient not exceeding 10%. For incandescent lamps, the maximum parameter reaches 4%. The worst indicator is for products with a power of 40 watts.

Among all available electrical lighting fixtures, incandescent bulbs get hotter. Most of the current is converted into thermal energy, so the device is more like a heater than a light source. Luminous efficiency is in the range from 5 to 15%. For this reason, certain norms are prescribed in the legislation that prohibit, for example, the use of incandescent lamps of more than 100 watts.

Usually, a 60 W lamp is enough to illuminate one room, which is characterized by a slight heating.

When considering the emission spectrum and comparing it with natural light, two important remarks can be made: the luminous flux of such lamps contains less blue and more red light. However, the result is considered acceptable and does not lead to fatigue, as is the case with daylight sources.

Operating parameters

When operating incandescent lamps, it is important to consider the conditions for their use. They can be used indoors and outdoors at a temperature of at least -60 and no more than +50 degrees. Celsius. At the same time, air humidity should not exceed 98% (+20 degrees Celsius). Devices can work in the same circuit with dimmers designed to control light output by changing the light intensity. These are cheap products that can be independently replaced even by an unskilled person.

Kinds

There are several criteria for classifying incandescent lamps, which will be discussed below.

Depending on the lighting efficiency, incandescent lamps are (from worst to best):

• vacuum;
• argon or nitrogen-argon;
• krypton;
• xenon or halogen with an infrared reflector installed inside the lamp, which increases efficiency;
• with a coating designed to convert infrared radiation into the visible spectrum.

There are many more varieties of incandescent lamps related to their functional purpose and design features:

1. General purpose - in the 70s. of the last century they were called "normal lighting lamps". The most common and numerous category is products used for general and decorative lighting. Since 2008, the production of such light sources has been significantly reduced, which was associated with the adoption of numerous laws.
2. Decorative purpose. The flasks of such products are made in the form of graceful figures. The most common are candle-shaped glass vessels with a diameter of up to 35 mm and spherical (45 mm).
3. Local appointment. They are identical in design to the first category, but are powered by a reduced voltage - 12/24/36/48 V. They are usually used in portable lamps and devices that illuminate workbenches, machines, etc.
4. Illuminated with colored flasks. Often, the power of products does not exceed 25 W, and for coloring, the inner cavity is covered with a layer of inorganic pigment. Much less often you can find light sources, the outer part of which is painted with colored varnish. In this case, the pigment fades and crumbles very quickly.

1. Mirrored. The flask is made in special form, which is coated with a reflective layer (for example, by aluminum spraying). These products are used to redistribute the luminous flux and improve lighting efficiency.
2. Signal. They are installed in lighting products designed to display any information. They are characterized by low power and are designed for continuous operation. To date, almost useless due to the availability of LEDs.
3. Transport. Another broad category of lamps used in vehicles. They are characterized by high strength, vibration resistance. They use special plinths that guarantee strong fastening and the possibility of quick replacement in cramped conditions. Can be powered by 6V.
4. Projector. High-power light sources up to 10 kW, characterized by high luminous efficiency. The coil is stacked compactly to provide better focus.
5. Lamps used in optical devices - for example, film projection or medical equipment.

Special Lamps

There are also more specific types of incandescent lamps:

1. Switchboard - a subcategory of signal lamps used in switchboards and performing the functions of indicators. These are narrow, oblong and small-sized products having parallel contacts of a smooth type. Due to this, they can be placed in buttons. Marked as "KM 6-50". The first number indicates the voltage, the second - the amperage (mA).
2. Perekalnaya, or photolamp. These products are used in photographic equipment for normalized forced mode. It is characterized by high luminous efficiency and color temperature, but a short service life. The power of Soviet lamps reached 500 watts. In most cases, the flask is matted. Today they are practically not used.
3. Projection. Used in overhead projectors. High brightness.

A double-filament lamp comes in several varieties:

1. For cars. One thread is used for the low beam, the other for the high beam. If we consider lamps for tail lights, then the threads can be used for a brake light and side light, respectively. The additional screen can cut off the rays, which in the dipped beam lamp can blind drivers of oncoming vehicles.
2. For aircraft. In a landing light, one filament can be used for low light and the other for high light, but requires external cooling and short operation.
3. For railway traffic lights. Two threads are needed to increase reliability - if one burns out, the other will glow.

Let's continue to consider special incandescent lamps:

1. A headlight lamp is a complex design for moving objects. Used in automotive and aviation technology.
2. Low inertia. Contain a thin filament. It was used in sound recording systems of the optical type and in some types of phototelegraphy. Nowadays, it is rarely used, since there are more modern and improved light sources.
3. Heating. Used as a heat source in laser printers and copiers. The lamp has a cylindrical shape, is fixed in a rotating metal shaft, to which paper with toner is applied. The roller transfers heat, which causes the toner to bleed.

efficiency

Electric current in incandescent lamps is converted not only into light visible to the eye. One part goes to radiation, the other is transformed into heat, the third - to infrared light, which is not fixed by the visual organs. If the temperature of the conductor is 3350 K, then the efficiency of the incandescent lamp will be 15%. A conventional 60 W lamp with a temperature of 2700 K is characterized by a minimum efficiency of 5%.

The efficiency is enhanced by the degree of heating of the conductor. But the higher the heating of the thread, the shorter the service life. For example, at a temperature of 2700 K, the light bulb will shine for 1000 hours, 3400 K - many times less. If you increase the supply voltage by 20%, then the glow will double. This is irrational, since the service life will be reduced by 95%.

Pros and cons

On the one hand, incandescent lamps are the most affordable light sources, on the other hand, they are characterized by a lot of shortcomings.

Advantages:

• low cost;
• there is no need to use additional devices;
• ease of use;
• comfortable color temperature;
• resistance to high humidity.

Flaws:

• fragility - 700–1000 hours, subject to all rules and operating recommendations;
• low light output - efficiency from 5 to 15%;
• fragile glass bulb;
• the possibility of an explosion when overheated;
• high fire danger;
• voltage fluctuations significantly reduce the service life.

How to increase service life

There are several reasons why the life of these products may be reduced:

• voltage drops;
• mechanical vibrations;
• high ambient temperature;
• broken connection in the wiring.

1. Select products that are suitable for the mains voltage range.
2. Carry out the movement strictly in the off state, because the product will fail due to the slightest vibrations.
3. If the lamps continue to burn out in the same cartridge, then it must be replaced or repaired.
4. When operating on a landing, add a diode to the electrical circuit or turn on two lamps of the same power in parallel.
5. To break the power circuit, you can add a device for smooth switching.

Technologies do not stand still, they are constantly developing, so today traditional incandescent lamps have been replaced by more economical and durable LED, fluorescent and energy-saving light sources. The main reasons for the production of incandescent lamps remain the presence of less technologically developed countries, as well as well-established production.

You can buy such products today in several cases - they fit well into the design of a house or apartment, or you like the soft and comfortable spectrum of their radiation. Technologically, these are outdated products.

Parsing the structure of an incandescent lamp (Figure 1, a) we find that the main part of its design is the filament body 3 , which, under the action of an electric current, is heated up to the appearance of optical radiation. This is actually based on the principle of operation of the lamp. The fastening of the filament body inside the lamp is carried out using electrodes 6 , usually holding its ends. Through the electrodes, an electric current is also supplied to the filament body, that is, they are still internal links of the conclusions. With insufficient stability of the filament body, use additional holders 4 . The holders are soldered onto the glass rod 5 , called a rod, which has a thickening at the end. The stem is associated with a complex glass part - a leg. Leg, it is shown in Figure 1, b, consists of electrodes 6 , plates 9 , and stem 10 , which is a hollow tube through which air is pumped out of the lamp bulb. General connection between each other intermediate conclusions 8 , rod, plate and stem forms a spatula 7 . The connection is made by melting glass parts, during which an exhaust hole is made. 14 connecting the internal cavity of the exhaust tube with the internal cavity of the lamp bulb. For supplying electric current to the filament through the electrodes 6 apply intermediate 8 and external findings 11 connected to each other by electric welding.

Figure 1. The device of an electric incandescent lamp ( a) and its legs ( b)

For isolating the filament body, as well as other parts of the light bulb, from external environment, glass flask is used 1 . The air from the inner cavity of the flask is pumped out, and instead an inert gas or a mixture of gases is pumped in. 2 , after which the end of the stem is heated and sealed.

For supplying electric current to the lamp and fixing it in an electric cartridge, the lamp is equipped with a base 13 , the attachment of which to the neck of the flask 1 carried out with the help of base mastic. Solder the lamp leads to the corresponding places of the base 12 .

The light distribution of the lamp depends on how the filament body is located and what shape it is. But this applies only to lamps with transparent flasks. If we imagine that the filament is an equally bright cylinder and project the light emanating from it onto a plane perpendicular to the largest surface of the luminous filament or spiral, then the maximum luminous intensity will be on it. Therefore, in order to create the desired directions of light forces, in various designs of lamps, the filaments are given a certain shape. Examples of filament shapes are shown in Figure 2. A straight, non-spiralized filament is almost never used in modern incandescent lamps. This is due to the fact that with an increase in the diameter of the filament, heat loss through the gas filling the lamp decreases.

Figure 2. The design of the heating body:
a- high-voltage projection lamp; b- low-voltage projection lamp; in- providing an equally bright disk

A large number of heating bodies are divided into two groups. The first group includes filaments used in general purpose lamps, the design of which was originally conceived as a radiation source with a uniform distribution of light intensity. The purpose of designing such lamps is to obtain maximum light output, which is achieved by reducing the number of holders through which the filament is cooled. The second group includes the so-called flat filaments, which are made either in the form of parallel spirals (in high-power high-voltage lamps) or in the form of flat spirals (in low-power low-voltage lamps). The first design is made with a large number of molybdenum holders, which are fastened with special ceramic bridges. A long filament is placed in the form of a basket, thereby achieving a large overall brightness. In incandescent lamps intended for optical systems, the filaments must be compact. To do this, the filament body is rolled into a bow, double or triple helix. Figure 3 shows the luminous intensity curves generated by filaments of various designs.

Figure 3. Luminous intensity curves for incandescent lamps with various bodies glow:
a- in a plane perpendicular to the axis of the lamp; b- in a plane passing through the axis of the lamp; 1 - ring spiral; 2 - straight spiral; 3 - spiral located on the surface of the cylinder

The required luminous intensity curves of incandescent lamps can be obtained by using special flasks with reflective or diffusing coatings. The use of reflective coatings on an appropriately shaped bulb allows for a considerable variety of luminous intensity curves. Lamps with reflective coatings are called mirrored (Figure 4). If it is necessary to ensure particularly accurate light distribution in mirror lamps, flasks made by pressing are used. Such lamps are called lamps-headlights. Some designs of incandescent lamps have metal reflectors built into the bulbs.

Figure 4. Mirrored incandescent lamps

Materials used in incandescent lamps

Metals

The main element of incandescent lamps is the filament body. For the manufacture of a heating body, it is most advisable to use metals and other materials with electronic conductivity. In this case, by passing an electric current, the body will heat up to the required temperature. The material of the heating body must meet a number of requirements: to have a high melting point, plasticity, which allows drawing wires of various diameters, including very small ones, a low evaporation rate at operating temperatures, which leads to a high service life, and the like. Table 1 shows the melting points of refractory metals. Most refractory metal is tungsten, which, along with high ductility and low evaporation rate, ensured its widespread use as the filament of incandescent lamps.

Table 1

Melting point of metals and their compounds

The evaporation rate of tungsten at temperatures of 2870 and 3270°C is 8.41×10 -10 and 9.95×10 -8 kg/(cm²×s).

Of other materials, rhenium can be considered promising, the melting point of which is slightly lower than that of tungsten. Rhenium lends itself well to mechanical processing in a heated state, is resistant to oxidation, and has a lower evaporation rate than tungsten. There are foreign publications on the production of lamps with a tungsten filament with rhenium additives, as well as coating the filament with a layer of rhenium. Of non-metallic compounds, tantalum carbide is of interest, the evaporation rate of which is 20–30% lower than that of tungsten. An obstacle to the use of carbides, in particular tantalum carbide, is their brittleness.

Table 2 shows the main physical properties of an ideal filament made of tungsten.

table 2

Main physical properties of tungsten filament

An important property of tungsten is the possibility of obtaining its alloys. Details from them retain a stable shape at high temperatures. When the tungsten wire is heated, during the heat treatment of the filament body and subsequent heating, its internal structure called thermal recrystallization. Depending on the nature of the recrystallization, the filament body may have greater or lesser dimensional stability. The nature of recrystallization is influenced by impurities and additives added to tungsten during its manufacture.

The addition of thorium oxide ThO 2 to tungsten slows down the process of its recrystallization and provides a fine crystalline structure. Such tungsten is strong under mechanical shock, however, it sags strongly and is therefore not suitable for the manufacture of filaments in the form of spirals. Tungsten with a high content of thorium oxide is used for the manufacture of gas discharge lamp cathodes due to its high emissivity.

For the manufacture of spirals, tungsten is used with an additive of silicon oxide SiO 2 together with alkali metals - potassium and sodium, as well as tungsten containing, in addition to those indicated, an additive of aluminum oxide Al 2 O 3. The latter gives the best results in the manufacture of coils.

The electrodes of most incandescent lamps are made of pure nickel. The choice is due to the good vacuum properties of this metal, which releases the gases sorbed in it, high current-carrying properties, and weldability with tungsten and other materials. The malleability of nickel makes it possible to replace welding with tungsten by compression, which provides good electrical and thermal conductivity. Vacuum incandescent lamps use copper instead of nickel.

Holders are usually made of molybdenum wire, which retains its elasticity at high temperatures. This makes it possible to maintain the filament body in a stretched state even after it has expanded as a result of heating. Molybdenum has a melting point of 2890 K and a temperature coefficient of linear expansion (TCLE) in the range from 300 to 800 K equal to 55 × 10 -7 K -1 . Molybdenum is also used to make bushings in refractory glass.

The terminals of incandescent lamps are made of copper wire, which is butt welded to the inputs. Low-power incandescent lamps do not have separate leads; their role is played by elongated inputs made of platinum. To solder the leads to the base, tin-lead solder of the POS-40 brand is used.

glass

Bars, plates, stems, flasks and other glass parts used in the same incandescent lamp are made of silicate glass with the same temperature coefficient of linear expansion, which is necessary to ensure the tightness of the welding points of these parts. The values ​​of the temperature coefficient of linear expansion of lamp glasses must ensure that consistent junctions are obtained with the metals used to make the bushings. The most widely used glass brand SL96-1 with a temperature coefficient equal to 96 × 10 -7 K -1 . This glass can operate at temperatures from 200 to 473 K.

One of the important parameters of glass is the temperature range within which it retains its weldability. To ensure weldability, some parts are made of SL93-1 glass, which differs from SL96-1 glass. chemical composition and a wider temperature range in which it retains weldability. Glass brand SL93-1 is distinguished by a high content of lead oxide. If it is necessary to reduce the size of the flasks, more refractory glasses are used (for example, grade SL40-1), the temperature coefficient of which is 40 × 10 -7 K -1 . These glasses can operate at temperatures from 200 to 523 K. The highest operating temperature is SL5-1 quartz glass, incandescent lamps from which can operate at 1000 K or more for several hundred hours (the temperature coefficient of linear expansion of quartz glass is 5.4 × 10 -7 K -1). Glasses of the listed brands are transparent for optical radiation in the wavelength range from 300 nm to 2.5 - 3 microns. Transmission of quartz glass starts from 220 nm.

Inputs

The bushings are made of a material that, along with good electrical conductivity, must have a thermal coefficient of linear expansion, which ensures that consistent junctions are obtained with glasses used for the manufacture of incandescent lamps. Consistent junctions are called junctions of materials, the values ​​of the thermal coefficient of linear expansion of which in the entire temperature range, that is, from the minimum to the glass annealing temperature, differ by no more than 10 - 15%. When soldering metal into glass, it is better if the thermal coefficient of linear expansion of the metal is slightly lower than that of glass. Then, when cooled, soldered glass compresses the metal. In the absence of a metal having the required value of the thermal coefficient of linear expansion, it is necessary to produce non-matched solder joints. In this case, the vacuum-tight connection of metal with glass over the entire temperature range, as well as the mechanical strength of the soldered joint, are ensured by a special design.

A matched junction with SL96-1 glass is obtained using platinum bushings. The high cost of this metal led to the need to develop a substitute, called "platinum". Platinite is a wire made of an iron-nickel alloy with a temperature coefficient of linear expansion smaller than that of glass. When a copper layer is applied to such a wire, it is possible to obtain a highly conductive bimetallic wire with a large temperature coefficient of linear expansion, depending on the layer thickness of the superimposed copper layer and the thermal coefficient of linear expansion of the original wire. It is obvious that such a method of matching the temperature coefficients of linear expansion allows matching mainly in terms of diametrical expansion, leaving the temperature coefficient of longitudinal expansion inconsistent. To ensure better vacuum density of junctions of SL96-1 glass with platinite and enhance wettability over a layer of copper oxidized over the surface to cuprous oxide, the wire is covered with a layer of borax (sodium salt of boric acid). Sufficiently strong solder joints are provided when using platinum wire with a diameter of up to 0.8 mm.

Vacuum-tight soldering into SL40-1 glass is obtained using molybdenum wire. This pair gives a more consistent seal than SL96-1 glass with platinum. The limited use of this solder is due to the high cost of raw materials.

To obtain vacuum-tight bushings in quartz glass, metals with a very low thermal coefficient of linear expansion are required, which do not exist. Therefore, I get the desired result thanks to the input structure. The metal used is molybdenum, which has good wettability with quartz glass. For incandescent lamps in quartz bulbs, simple foil bushings are used.

gases

Filling incandescent lamps with gas allows you to increase the operating temperature of the filament body without reducing the service life due to a decrease in the rate of sputtering of tungsten in a gaseous medium compared to sputtering in a vacuum. The spray rate decreases with increasing molecular weight and filling gas pressure. The pressure of the filling gases is about 8 × 104 Pa. What gas to use for this?

The use of a gaseous medium leads to heat losses due to heat conduction through the gas and convection. To reduce losses, it is advantageous to fill the lamps with heavy inert gases or their mixtures. These gases include air-derived nitrogen, argon, krypton and xenon. Table 3 shows the main parameters of inert gases. Nitrogen in its pure form is not used because of the large losses associated with its relatively high thermal conductivity.

Table 3

Basic parameters of inert gases

Color music or just lighting with an unusual color is an interesting solution that can come in handy in decorating any room. Finding bright light bulbs on the market and in stores is quite difficult, so the only way out is to create colored light bulbs yourself.

The usual painting options may not be suitable for giving the color of the light bulb, as it will burn the applied layer due to heating. Therefore, for work it is recommended to choose LED lamps, energy-saving, or incandescent lamps of 25 watts. When working on a light bulb, it must be remembered that the color of the brightness of the glow will depend on the density of the color coating.

Using different dyes, coating intensities and the methods described below, you can create a rich collection of different light bulbs with an interesting glow in a few minutes.

Coloring with paste

To color the pen blue, you can take the paste from the ballpoint pen. To paint the lamp in the color of the selected paste, you will need to carefully remove the tip, blow the ink onto a sheet of paper or oilcloth. Then, holding the light bulb by the base, rub it with the leaked contents of the pen.
You can control the intensity of the coating with acetone, cologne or alcohol.

Nail polish

Quick-drying varnishes are an excellent dye. It is convenient to apply varnish with a brush or cotton pad. A huge advantage of this method is a wide selection of shades.
However, the varnish burns out when heated to more than 200 degrees, so you need to be more careful when using it.

PVA

PVA glue is universal and sets on most surfaces. It itself has a white cloudy tint, but after drying it becomes transparent. If you mix glue with a water-soluble dye or pigment from a printer, and then cover a light bulb with it, you can get quite a good result.

Autoenamel

A relevant method for the owner of a car: usually car enamel is sold in aerosol cans. The method of applying the shade is very simple, the coating can withstand up to 200 degrees.

In order not to get too thick a layer that will darken the bulb, it is recommended to spray the contents of the aerosol at a distance of 30-40 cm from the object.

stained glass paints

Ideal for creating a colored light bulb - stained glass paints. To work with a light bulb, you will need water-soluble, for firing. The layer will not burn out with strong heating, but will only become stronger.

This method has a significant drawback - this is the price. One small tube of 50 grams is dressed to cost the buyer 150–200 rubles.

Silicon organics

Paints intended for painting surfaces that are often heated. They are durable and guaranteed not to burn out, even if the light bulb is on constantly. The upper limit of the range is 600 degrees, so you don’t have to worry about quality and service life.

Tsaponlak

You can buy this coating in a store specializing in radio components. The main function of the coating is to protect tracks and solder joints from short circuits. Since the operating temperature of the transistors reaches 150 degrees, the product is suitable even before coating the light bulbs.

These are the simplest and available ways cover a rather capricious material - glass. The choice narrows several times if the question concerns light bulbs that burn often and for a long time, because not all dyes can withstand high temperatures.