The consistency of the epoxy resin significantly affects the result of the work. A thinner resin is easier and more even to apply by brush or roller, penetrates fiberglass faster and penetrates porous surfaces better. This is especially important for the manufacture of decorative products and for, which is so viscous that at a temperature of 10 ° C and below it is essentially a solid body. How to make the existing resin less viscous, so that it is more convenient to work with and the result is as expected?
The most obvious answer to this need is to purchase a more liquid resin. For example, ED-20 is easy to replace with resin (viscosity 12-14 compared to 13-20 for ED-20) or resin (viscosity 8-12), and if we are talking about decorative products, it is better to purchase a special resin for casting.
Another obvious way to reduce the viscosity of the resin is to thin it. However, this method is not optimal and is more suitable for specialists in the field of chemical engineering. The hardened dilute resin is characterized by a more porous structure, which is not visible to the naked eye, but noticeably affects strength and hardness.
Solvent evaporation during curing can cause shrinkage and cracking. Only 5% dilution of the resin with a lacquer thinner reduces the viscosity by 60%, while the strength of the cured composition drops by 35%.
An acceptable method of dilution can be considered the addition of a plasticizer, preferably, which does not affect the properties of the resin in a negative way, being itself a curable epoxy compound, however, it has a saturated color (from orange to black) and is added in a concentration of no more than 5-10%, which will not the resin is radically more liquid.
Heating is a more successful and reliable way to increase the fluidity of the resin. After polymerization, such a composition will not differ in properties from a composition cured at ordinary temperature. As a rule, the hardener and resin are heated separately, after which the two components are mixed. It is possible to heat the surface to be treated. This method is usually used when working with wood, especially if the purpose of the work is to impregnate wood: heated wood perfectly absorbs resin. It is important to eliminate the source of heat before work and apply the composition to the cooling surface.
The heating temperature should not be high. The walls of the heated container should not burn the skin (this corresponds to a temperature of about 50 °). Higher heating leads to deterioration of the composition. To get the resin and hardener at this temperature, you can heat them with a heat lamp. If there is a heating cabinet that maintains a constant temperature, this is the optimal solution for heating the components, but this is rarely the case in life. The most common method of heating in everyday life is a "water bath", when tightly closed containers with resin are placed in warm water for 10-20 minutes.
If the need for heating arises regularly, you can try to make a heating cabinet with your own hands: for this, an incandescent lamp or a heating pad and a thermometer are placed in a plywood box, preferably additionally reinforced with some kind of non-combustible heat insulator, and a thermometer to control the temperature.
When using heat, care must be taken to plan the work: a warm composition hardens much faster than the same composition at room temperature. And one more thing: when working with electrical appliances and flame sources, first of all, take care of fire safety.
In both methods of reducing the viscosity, it must be remembered that the process of working with epoxy resin with a decrease in the viscosity of the composition will differ significantly from the usual (primarily in the curing speed). It makes sense to try the chosen method on a small amount of the composition before bringing it to life.
The reader already knows a little about what a substrate is. It allows you to firmly fix the plate being processed, softens the force of impact and ensures accurate contouring and relief. Plastic materials are used as a filler for the substrate. You can use tarpaulin bags filled with sand, on which the general shape of the relief is punched out. For individual shallow parts, sheet lead or rubber is used as a substrate.
resin substrate
The most common substrate material is resin. Natural resin was used in ancient times, mixing it with sand for greater viscosity.
Currently, it is easier and more affordable to use artificial resin - bitumen. Its viscosity and other properties depend on the brand. For embossed works, it is more convenient to use bitumen No. 4 and 5, but you can mix resin No. 3 and 5 in equal proportions. Bitumen No. 3 is too thin and melts quickly, so it cannot be used without additives in the preparation of the substrate.
You can give the resin additional viscosity if you mix it with well-sifted river sand in a ratio of 1: 3. If the sand is exceeded, the substrate will turn out to be very hard, which will affect the quality of the minting. There are many fillers available to add extra softness and stickiness, but wax and rosin are the most commonly used. The wax content should not exceed 10% of the total volume, very little rosin is required.
The mixture before pouring into the box is heated to a liquid state and thoroughly mixed until smooth. Resin is most often heated on a fire that can be bred on the street, or they do it at home on an electric stove in a well-ventilated area. It is preferable to heat the resin on an electric stove, since hot resin ignites when it comes into contact with an open fire.
The fire should be uniform and weak: on high heat, the resin begins to bubble and may catch fire. Since the volume of the resin increases slightly when heated, it is not necessary to fill it into the container to the brim. For stirring, a special metal spatula with a long handle is used so as not to burn yourself with splashes.
When heating the resin, safety precautions must be observed. If molten bitumen enters the tree, it can catch fire. It is very difficult to extinguish a tar fire, so in case of a fire, it is better to stock up on a fire extinguisher or have a supply of water on hand.
Hot resin is poured into pre-prepared boxes (Fig. 111).
Rice. 111. Boxes for substrates: a - wooden; b - metal.
Their dimensions should be several centimeters larger than the dimensions of the workpiece, and their depth depends on the height of the relief. The boxes are made from both wood and metal.
The walls of a wooden box (Fig. 111, a) should not be thinner than 15 mm, and a metal box (Fig. 111, b) is made of tin or roofing iron so that the resin in it can be heated by placing the box on an electric stove.
When pouring, it is necessary to pay attention to the fact that there are no voids left in it, since on the voids the metal can break through under the blow of the coinage. If bubbles still remain, they are heated to the ground and stirred.
After the resin hardens, its top layer is reheated with a blowtorch or electric heater and leveled with a special mixer. In addition, it is recommended to warm up the plate a little.
The workpiece is carefully lowered into the softened resin at an equal distance from the edges, making sure that it does not drown completely in it. For uniform grinding, the surface with which the metal sheet comes into contact with the resin is preliminarily degreased. So that no air bubbles remain under the plate, it is not lowered immediately, but starting from one edge, pressing it to the surface with a clean cloth, as shown in Fig. 112.
Rice. 112. Grinding of a metal plate.
It is very important that the metal is pitched over the entire area, otherwise it will be impossible to correct the defects of the future product.
Periodically, while working on high reliefs, it becomes necessary to heat up the resin already poured into the boxes. It is convenient to heat metal boxes directly on an electric stove, but its spiral must be closed.
If the boxes are made of wood, then the filling can be heated by placing the box on a baking sheet in the oven of a conventional gas stove. In this case, one must be very careful: if the temperature is too high, it can catch fire, even if flames do not fall on its walls.
More often, resin in wooden boxes is heated using a heating device fixed above them, which is installed at a distance of 20–25 cm from the top layer.
You can also use electric heaters with mirror reflectors (Fig. 113).
Rice. 113. Heating with electric heaters.
For volumetric coinage, special bowls can be used as a support. They are extruded from sheet steel in the shape of a hemisphere. Fill the pot with heated resin so that it protrudes slightly above the top edge of the slide. Until the resin has completely hardened, it is necessary to prepare a place on the pot for the product. The hot resin is covered with wet paper (so that the resin does not stick to the metal) and the workpiece is lightly pressed into the resin. An imprint is formed in which the product will be well retained. When working under the pot it is necessary to enclose a ring stand made of rubber.
From the book: Korshever N. G. Metalwork
Such a building material as bitumen has been used for pouring roofs for a very long time. Perhaps the reason for the popularity of bitumen is its cheapness. But preferring it to other more expensive materials, do not forget that bitumen is short-lived. Direct sunlight and rays are especially dangerous for him, from this he begins to melt and flow. And in winter, it cracks from severe frosts and this may cause leaks in the roof of the garage.
But if you still decide to use such a building material as bitumen, then consider the process of preparing it for pouring.
In order to prepare about 10 kg of bituminous mastic, you will need:
- 8.5 kg bitumen
- 1 kg of filler (it can be peat chips, asbestos, chalk sawdust, crushed mineral wool, etc.)
- 0.5 kg of used crankcase oil.
It is best to cook the bituminous mixture in a thick-walled boiler with a tightly closed lid. Bitumen can burn in thin-walled containers.
Bitumen should be heated gradually over low heat.
The heating temperature of bitumen ranges from 160-200 degrees. Heat up for 1-3 hours depending on the heating temperature, the higher it is, the less we heat the bitumen.
At a temperature above the specified maximum (220 and above), coke is formed in the bitumen, which significantly worsens the properties of the bitumen (it can crack).
The surest sign of bitumen overheating is the appearance of green-yellow smoke and bubbles.
We cook the bitumen until a homogeneous state and the appearance of a glossy surface.
After that, remove it from the heat and add filler and crankcase oil in small portions. And immediately, with hot bitumen, we begin to carefully pour the roof of the garage, which by this moment should be thoroughly cleaned of all kinds of contaminants, dried and prepared for pouring. When applying bitumen, we use kvatch or we apply bitumen in bulk.
Then a roofing material is glued onto the hot bitumen in order to prevent overheating of the bitumen in the sun in the future.
You can cook bitumen for pouring roofs yourself on a fire, take a barrel or a large pan (since you usually need a lot of bitumen), take 10 kg of resin, a liter of mining (engine oil, can be purchased at service stations) and a kilogram of building chalk.
We put the bricks on the edge, a container on it, resin in the container (put about a couple of kilos, and then put the rest when melted), kindle a fire under the container, using small chips (try to keep the fire small so that the resin melts, and does not boil around not straightened pieces.
As soon as the resin melts a little bit, we fill in the chalk and pour in the mining, mix thoroughly - everything is ready, you can tar the roof and glue the roofing material.
The prepared bitumen, when cooled, will solidify in a container, it can be reheated and used.
Filling the roof with bitumen is a necessary thing and you need to do this work so that you don’t return to it for a long time, so that there are no leaks. And this is done simply in the old fashioned way, if I may say so. We take a large old container - for example, an iron barrel, throw pieces of bitumen into it (it’s better to make smaller pieces), put it on a tripod and set fire to a blowtorch, let the bitumen melt completely. Then we add mining to the bitumen (this is used engine oil), mix thoroughly and then chalk and also stir. The proportions are: 10 kg. bitumen; ! liter of mining; 1 kg of chalk.
Epoxy is a strong adhesive used on many types of surfaces, from plastic to metal. Once this resin hardens, it becomes very difficult to remove it. Epoxy resin is used in a liquid state. When it is mixed with a solvent, the temperature of the substance rises, then it begins to cool and solidify. You can remove the epoxy by bringing it back to a liquid or at least a gel state, after which it can be removed from the surface. With patience and the necessary precautions, you should be able to remove the epoxy fairly easily.
Steps
Removing epoxy by heating
- If epoxy is stuck to plastic, marble, cement, vinyl, or metal, any chemical will only act on the surface without penetrating the interior, as it does with wood.
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Heat up the epoxy with a hair dryer for a few minutes. It is necessary that the resin is heated above 90 ° C, after which it will soften. In this case, it is better not to keep the hair dryer motionless, but to drive it from side to side, warming up the resin. If epoxy sticks to a plastic or wood surface, be careful not to overheat it or the surface may catch fire.
Heat up the epoxy in small areas. Don't try to heat the resin all over the spot at once - you won't be able to keep it hot for long enough. Instead, heat up small areas that are 5–8 centimeters long. Having completely peeled off one section from the surface, move on to the next one. So gradually, moving along the edge, you can remove all the epoxy.
Peel off the heated resin. Use a knife, blade, or other sharp object to remove epoxy from the surface. In this case, it may turn out that the resin has not warmed up to the full depth. In this case, reheat it, continuing to tear it off until it is completely removed.
- Do not reheat the epoxy immediately after the previous heating. Wait a few minutes for the resin to cool before reheating it, otherwise the surface may overheat and create a fire hazard.
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Scrape off the brittle epoxy. This can be done with a scraper, or simply break up the fragile resin by tapping it with a rubber or wooden mallet. The cooled resin will crumble into fragments, crumbling from the surface. After that, carefully collect the fragments in a dustpan and immediately discard them. You can also use a vacuum cleaner to be sure to remove any microscopic debris.
- Do not apply too much force to avoid damaging the surface under the epoxy. If the resin does not separate easily enough, spray the refrigerant again, freezing it more.
Put on gloves and goggles. When heated, epoxy releases vapors that are harmful to the eyes. To protect against them, simple glasses are not enough. You will need goggles that completely cover your eyes and fit snugly against your skin, with no holes for vapors to seep into your eyes. You should also wear rubber gloves that cover your wrists by at least 7-8 cm. It is advisable to use gloves with an elastic band that fits snugly against the skin so that air does not penetrate under them.
Wear closed clothing that covers your skin. Look for slacks and a long-sleeved, closed shirt. If your shirt has buttons, make sure they are all buttoned up. Thus, you protect your skin from harmful fumes released when the epoxy is heated.
Apply acetone to the surface. If the epoxy is stuck to the wood surface, dampen it with acetone and wait at least an hour for it to soak in and the resin soften. You can immerse the object in acetone, or moisten the surface of the resin with it. This will absorb the acetone into the wood.
Removing epoxy with chemicals
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Put on safety goggles and gloves. Chemical reagents can pose a great danger to the skin and eyes. You will need goggles that fit snugly around your face, with no gaps between your skin and goggles for air to seep through. In addition, you will need a pair of thick rubber gloves that cover your wrists by at least 7-8 cm.
Open windows and doors. It is extremely important to create a continuous flow of air in the room, which will carry with it the harmful fumes created by the reagents. Leaving windows and doors closed will greatly increase the risk of poisoning.
- Be sure to turn off the air conditioner and heater so as not to saturate the air with harmful fumes.
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Choose a substance that can soften the epoxy. It is also important that the selected reagent does not damage the surface to which the resin adheres. Some substances can damage fabric, plastic or vinyl. Strong chemicals can even corrode the surface before the epoxy softens. Prepare a cleaning solution. After you apply the bleach and wait about an hour for it to saturate the epoxy, it should be treated with a neutralizer before removal. Prepare it by diluting 2-3 tablespoons of sodium orthophosphate in 4 liters of hot water in a small bucket. Epoxy resin can be simply poured with a neutralizer, or applied with a sponge. Wait at least 5 minutes for the neutralizer to soak into the resin.
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Scrape off the epoxy from the surface. Use a knife, blade or other sharp object for this. Immediately place the resin fragments in a paper towel and throw them in the trash can. It is necessary to remove all the resin, and with it the used reagents. If the surface is not completely free of epoxy, saturate the resin with the reagent again and try to remove it again.
- After removing the epoxy, wipe the surface with a cloth dampened with warm soapy water. This is necessary in order to remove the remnants of chemical reagents, which is especially important if there are children and pets in the house.
- Treat the epoxy in small areas. Do not try to remove the entire stain at once if it is large. Shoot sections 5-8 centimeters long.
- Apply the same method 2-3 times in a row. Sometimes in one way or another it is possible to remove only the top layer of epoxy, so sometimes the procedure must be repeated several times.
- Consult with experts in the store of household goods. They may be able to advise you on a method suitable for your particular case. Experts will advise you on the most suitable product for removing epoxy adhesive.
Warnings
- Keep children and pets away from you while you are applying chemicals to the epoxy.
- Be sure to use safety goggles and gloves. Protect eyes and skin from harmful fumes.
- Make sure that the room is well ventilated - you do not want to undermine your health by inhaling harmful fumes.
