Using a compressor to paint allows you to save money, time and avoid pollution due to the propellants of spray bottles. To spray paint with a compressor, follow these instructions.
Steps
Method 1 of 4: Preliminary Steps
Step 1. Choose the paint and thinner
Oil-based enamels are easier to use with a compressor, but acrylics and latex paint can also be sprayed. If you add the right thinner, you allow the more viscous paint to flow down the tubes, metering valve and spout.
Step 2. Prepare the area you want to paint
Place plastic sheeting, fabric, scrap wood panels, or other material on the floor, ground, or furniture. For "fixed" material projects, like the one shown here, you will need to protect adjacent surfaces and be in a well-ventilated area.
- Protect nearby surfaces from "unintentional splashes" by covering them with paper and newspaper tape; on windy days and outdoors, the paint particles can go further than you imagine.
- Put the paint and thinner in suitable places where spills cannot do any damage.
Step 3. Put on a mask or respirator, safety glasses and gloves
These allow you to stay clean and safe from dangerous fumes and particles.
Step 4. Prepare the surface to be painted
Sand, brush or sand the rust and corrosion from the metal, remove any grease, dust or dirt and make sure everything is dry. Wash the surface: for oil paints, use white spirit; for latex and acrylics, use soap and water. Rinse thoroughly.
Step 5. Apply primer if needed
You can use the spray to apply the primer (follow the subsequent instructions as if it were paint) or a brush or roller. When you're done, sand with sandpaper if necessary.
Method 2 of 4: Prepare the Compressor
Step 1. Turn on the air in the compressor
Use a little air to apply the primer and to test the spray gun, then let the pressure build up while you prepare the paint. The compressor should have a pressure gauge that allows you to check the pressure and set it correctly for spraying; otherwise, pressure fluctuations can occur which cause the spray power to suddenly increase or decrease.
Step 2. Adjust the compressor pressure gauge between 0, 8 and 1.7 atmospheres
The exact pressure depends on your spray gun, so check the user manual (or the tool itself) for details.
Step 3. Connect the air hose fitting to the spray gun
Make sure it is tightly closed; you can fix the fitting with Teflon tape to make sure it is airtight. This is not necessary if the gun and hose have automatic fittings.
Step 4. Pour a small amount of diluent into the spray gun tank (it is usually attached to the bottom of the gun)
Add enough to submerge the siphon.
Step 5. Open the dose valve slightly
Usually it is the lower one of the two screws that are on the gun handle.
Step 6. Load the spray
Point the nozzle into a waste bucket and pull the trigger. It will take a couple of seconds before the liquid comes out, since at the beginning there is only air. After a moment you should see a stream of thinner. If nothing comes out of the spout, you should disassemble the gun and check what jams the mechanism or if there is something blocking the siphon.
Step 7. Empty the diluent from the tank
You can help yourself with a funnel to put the diluent back into the original container. White spirit or turpentine (the most common diluents) are flammable liquids and should always be stored in their original containers.
Method 3 of 4: Paint
Step 1. Prepare enough paint for your work
After opening the paint can, mix it well, then pour enough for your work into another clean container. If the paint has not been used for a long time, it is a great idea to mix it and filter it to remove any lumps and clots that may have formed. These lumps could clog the siphon and valve blocking the spray.
Step 2. Dilute the paint with the appropriate product
The exact percentage of thinner depends on the type of paint you use, the airbrush and the nozzle, but it is usually diluted at 15-20% for a fluidity suitable for the spray. Check how diluted the paint of a spray can is, it might give you an idea of how it should be.
Step 3. Fill the tank about 2/3 full and attach it to the gun
If the tank connects under the gun with a fitting and a hook or screw, make sure you have it securely fastened; you don't want the tank to come off while you are painting.
Step 4. Hold the gun 15-25cm from the surface
Practice moving the gun from side to side or up and down in a continuous motion parallel to the surface. If you have never used spray paint before, do some practice to find the right feeling and to balance the weight.
Step 5. Pull the trigger on the gun
Keep moving it while holding to avoid dripping and applying too much paint in one spot.
It would be best to do a test on a scrap piece of wood or cardboard before tackling the main job. This way you can make the appropriate adjustments to the spout
Step 6. Overlap each step
This way you will not see the edges of each "pass" of the spray and you will not leave stains. Check for drops. Move quickly enough for the paint to stick as you spray.
Step 7. Refill the tank if you need more paint to finish the job
Do not leave the airbrush with the paint inside; if you need to take a break, remove the tank and spray some thinner through the gun before letting it sit.
Step 8. Wait for the paint to dry, then give it another coat if you want
For most paints, a good uniform "hand" is sufficient, but a second coat makes the finished work better. To improve adhesion between the two layers, it would be better to sand between coats if you use enamels or surface treatments with polyurethane or other glossy paints.
Method 4 of 4: Clean
Step 1. Remove any paint you don't use
If you have a lot of unused paint left, you can put it back in the original tin; remember, however, that it has already been diluted, so the next time you use it you will need to adjust the amount of diluent to put.
Epoxy paints that use a hardener cannot be returned to the original container; must be used completely or disposed of
Step 2. Rinse the siphon and tank with diluent
Remove any paint residue.
Step 3. Fill the tank about ¼ full with the diluent and spray until only the diluent comes out
If there is a lot of paint left in the tank or inside the gun, you will need to repeat this operation several times.
Step 4. Remove the masking tape and protective paper from the work area
Do it right away, before the paint dries; leaving the tape on the surface for a long time will allow the glue to settle, making it difficult to remove.
Advice
- Paint with horizontal or vertical movements. But avoid going both ways in the same job because the texture of the paint may not be uniform in the different angles you look at it from.
- Clean up always the gun carefully after using it. For dry oil-based paint you need to use acetone or a lacquer thinner.
- Read the instructions or the user manual of your airbrush. You need to become familiar with the capacity, viscosity, and type of paint your gun applies. The control systems of the airbrush used in the photographs are quite common for this type of spray gun. The upper valve adjusts the air volume; the one at the bottom the paint flow. The front of the nozzle is held in position by a threaded ring and the type of spray can be changed vertically or horizontally by turning it.
- Using compressed air instead of spray bottles allows you to customize colors, minimize air pollution and save money. However, it does release a certain amount of volatile particles which are used as solvents in many paints.
- Prepare enough paint to finish the job if you can, as subsequent mixes will never be perfectly identical to the first.
- Use hot water to dilute water-based paints (about 50 ° C). You may need to dilute acrylics with 5% warm water.
- Use an automotive catalytic reducer. It is formulated to accelerate drying and prevent dripping without affecting the final effect.
- It would not be bad to use an air filter or a dryer filter to remove moisture and dirt from the compressed air. These accessories should cost around € 150.
Warnings
- Never disconnect the air hose while the compressor is charged.
- Paint only in well-ventilated areas.
- Wear a respirator if you need to paint for long periods. Spend € 50 to buy a respirator or a painter's mask, to prevent lung disease. A respirator will completely filter out the paint vapors and you won't have to breathe them if you paint indoors.
- Some paints contain flammable solvents, especially "quick dry" and lacquer based ones. Avoid sparks, open flames and do not let vapors concentrate indoors.
