Powder painting is the process of applying a plastic coating to a metal; this coating is in the form of a powder and, when heated, turns into a liquid state and binds to the metal surface. Powder coating has many advantages over traditional coatings: it is more environmentally friendly, can be applied in a thick layer without drips, and looks modern. While some aspects of powder coating can be tricky, that won't stop the adventurous soul. Proper surface cleaning before painting and the tools used is the difference between an amateur and a professional.
Steps
Method 1 of 2: Method 1 of 2: Powder coating
Step 1. First, determine the type of material you are going to powder coat, then select the appropriate powder
Powder coating is done with thermoplastic or thermosetting polymer powder, and these powders are designed to adhere to a variety of base metals in order to obtain the best results.
See the next section for a detailed discussion of the differences between thermosetting and thermoplastic coatings. What's good for a car may not be good for a small keychain or decoration
Step 2. Disassemble all threaded or swivel joints, before you start painting, remove anything that you do not wish to paint
It sounds simple, but many people forget about it. Powder coating will glue everything (if done correctly): bearings, clamps, bolts and nuts, etc., will become useless after painting.
Step 3. Thoroughly clean the metal before painting
Sandblast metal (cast iron or steel) to remove rust, dirt, and other foreign materials. Cleaning with a chemical solvent will remove any grease, oil or paint, and light sanding will complete the surface preparation. Aluminum, magnesium and other soft alloy metals can be cleaned with a solvent, brush, and, if necessary, sanded with sandpaper.
- You can sandblast whatever you want to powder paint to bare metal. This is the first step in the process. If you don't have access to a sandblaster, you can use a wire attachment on a drill, sander, or sandpaper.
- The next step is to clean the metal of any remaining dirt. You can do this by soaking the part in acetone (if the part is small enough) or by wiping the metal with an acetone-soaked rag.
Step 4. Applying powder to the object to be powder coated
This is done with a special "gun" or "spray", powered by compressed air. They electrostatically charge the powder material so that it adheres to grounded metal objects and forms a coating. These tools are available from a variety of vendors and cost approximately $ 100. For experimental purposes, you can try applying the powder to a flat metal surface by spraying it directly onto that surface, spreading it out in a thin, even layer.
- Make sure to connect an electrostatic charge to the surface to be painted. The powder will not stick to the surface unless you apply a charge to it.
- Be careful after coating, before curing. Do not scrub or blow on the powder paint, as this will cause some of the powder to fall and make the coating thinner.
Step 5. The powder is baked at a temperature suitable for the powder material used
A conventional oven is suitable for this purpose if the product is small enough to fit, otherwise use infrared lamps or other heat sources. Typically, the object is heated from 175 ° C to 190 ° C for about 10 to 15 minutes, after which it is allowed to cool.
You can use your regular oven to powder coat small items. Just make sure not to use the oven for cooking after using it for powder painting. If you have already used a powder coating oven, it should not be used for cooking
Method 2 of 2: Method 2 of 2: Comparison of thermosets and thermoplastics
Step 1. Use thermoplastic finishes for items you may ever paint over, and thermoset finishes for items that will stay that way forever
The main difference between thermoplastic and thermosetting is the reversibility of the coating. As their name suggests, thermosetting coatings cannot be remelted after going through an irreversible chemical bonding process. Conversely, thermoplastic coatings can melt because no chemical process takes place.
Thermoset coatings are ideal for things like electronics and home appliances because they have to withstand higher temperatures, which can cause thermoplastic coatings to melt
Step 2. Choose the type of paint based on some characteristics of the coating
Thermosets and thermoplastics have different chemical properties, making them ideal for a variety of purposes. Knowing some of these properties will help you choose the type of coverage:
- Thermosets are said to enhance the structural integrity of painted surfaces, making them resistant to wear and tear and able to withstand harsh environments. They also impart excellent chemical and heat resistance to the surface of the part, as mentioned above.
- Thermoplastics offer a blend of strength and flexibility. They are widely used for items such as plastic bags or mechanical parts.
Step 3. Know the advantages and disadvantages of thermosetting coatings
Thermosetting powders are often used to coat machinery parts because of the high temperatures they can withstand.
- Advantages: beautiful appearance; cheap; give additional strength and stability; resistant to extreme temperatures.
- Disadvantages: An irreversible process means that thermosetting paints cannot be recycled; difficult to finish; the shape of the product cannot be changed.
Step 4. Know the advantages and disadvantages of thermoplastics
Thermoplastics are used for many elements, such as benches, that require both ductility and durability.
- Advantages: high slipperiness (smoothness) of the surface and strong adhesion to the metal surface.; can be recycled; able to withstand the change in the shape of the object (flexible); shockproof.
- Disadvantages: more expensive (usually); can melt at high temperatures.
Advice
- Clean and rinse metal surfaces, carefully remove all old paintwork residues.
- Work in a well-ventilated, clean area.
- Always preheat parts in an oven before coating. This will remove any grease or oil remaining on the metal surface. If the part is not preheated, any grease or oil that remains on the surface will form a bubble below the paint surface after the curing process.
- Powder coating is an environmentally friendly, corrosion and UV resistant coating. Although painting is best done on industrial equipment, you can experiment in a home workshop as well.
- Remember that you need to heat the powder coated object to cure it, so you need an oven to fit the part in or apply heat from an infrared lamp long enough for the paint to cure.
- A large number of powder coating equipment is sold in stores.
- Collect any excess powder for reuse.
Warnings
- Use a respirator, gloves and safety goggles when abrasive cleaning metal to remove rust.
- Do not use gas ovens.
- Ovens used for cooking are not recommended.
- Don't eat powder. This is deadly.
- Do not touch the part when removing it from the oven and until it has completely cooled down.
- Do not inhale powder.