The “do it yourself” master sometimes encountered such a problem. Immediately to be clear, there is no easy way to remove old paint from metal, wood or concrete. It is recommended to arm yourself up with patience and time.
In the following, you will see several ways to prepare the surface for new painting.

Which of them will be most effective depends on the type of paint, time spent on the surface, exposure to atmospheric conditions, and the like. So, it’s important to experiment. Try all the ways, combine them, when you determine the most effective in your case, get to work.

Required tools:
Scoop, wire brush, hair removal gloves, gloves, glasses, paint brush

Required time:
Depends on the surface
Required material: Skid colors, shingles;

The first way is to use a chemical approach. There is an asset called “skin colors”. Of course, this is the name of the brand, but it is used as a synonym for all the means of removing the old color. The company responsible for ejecting this product on the market has in time created a brand. So who still thinks it’s not important to be the first … there will be another, always.
It is important to note here that it is a strong base, and skin burns caused by the action of these bases are very painful and the wounds are difficult to heal. When working with such bases it is mandatory to use protective gloves and goggles. If, however, there is a spray on the skin, the site is washed with an aqueous solution of vinegar and then under a stream of cold water. Also, do not apply skid materials in small and uncluttered rooms as the inhalation of the vapor is harmful to health.

Now, if all the great warnings did not make you afraid to move on, of course, at your own risk. The application is very easy, brush (which you are ready to throw away) lubricate the gel liquid through the paint you want to remove and you can take a beer.

When you come back from a break after about 3 to 5 minutes, you will notice how the paint swelled and squeaked in the treated spots with the dye (the same thing was taken off by another manufacturer). Although the box says it can work at a temperature of 35 degrees Celsius, a practice has shown that its efficiency falls with a rise in temperature. So the suggestion is to use it in the shade when it’s temp. about 17-18 degrees. If it’s hot, cool it. As long as the gelato is good when the dilution is not removed. Some suggest that when the overcoat is painted, this spot is nylon, supposedly the reaction is better. It is necessary to try, experimenting people and going to the cosmos.

Now the harder part goes, scrutinized in the hands and slowly aggregate the color. You will notice that it now resembles the gum and that the removal is no longer so difficult. Depending on how many layers of paint are applied, you may have to repeat the procedure several times.

If you remove paint from concrete, the wires will be of great use. On the tree, it is not applicable since it leaves damage in the form of a scar. On concrete and metal, this is not a problem and its application will greatly accelerate and facilitate the process.

If you do not have patience, there is heavy artillery. There are various types of circular wire brushes, with a thinner wire, with twisted, for grinders, for drills and the like. Of course, it should also be noted here that the circular brushes generate high rotational vibrations, and it must be verified that the specified maximum speed, as defined by the manufacturer, corresponds to the maximum speed of the grinder or drill. If this is not the case, do not use it.

The next way is to use a hot air fan. Experienced masters will say that the gas turbine is much more efficient for the job. I hobby masters without experience I do not recommend the use of this tool without training in some irrelevant surfaces. However, for those brave, it’s about breners often used in the tin craft for heating the soldering blades 2-3 cm.

Brener is connected to a gas bottle and direct flame heating. Especially be careful when removing paint from wooden surfaces because both wood and paint are flammable. Something else, when you remove some old paint, wear a mask because of poisonous particles that were once part of the paint.

But let’s go back to a more elegant solution. For though the burner was the perfect solution for people, they would never have invented a hair dryer. Its use is very easy. Direct the source of warm air from a distance of 1-2 cm to the place with the old paint, wait a bit and then scratch, do not blow the dryer slowly gulp the paint. You will see that due to the temperature it’s very easy to slip off the substrate. It is important to note that you should work in a quiet time without wind because the wind pretty much reduces heat and the effects of the work are weaker.
Source: http://www.mojaradionica.com/Stara_farba_kako_je_skinuti.htm