Powder vs Liquid Coatings
Coatings protect and decorate almost every item in our lives. From mobile phones and automobiles, to factories, farm equipment, roadways and bridges; most everything we value is painted. Selecting the right paint or “coating solution” for your individual project or process may seem overwhelming, but it can be easier than you might imagine with your Sales and Technical team at U.S. Paint. Many of our customers ask us the difference between powder coatings and liquid coatings. There are in fact many differences, but here we will provide some of the main differences between their use cases.
The largest differentiator between liquid and powder coatings is that powder coating is chiefly for metal substrates, or substrates that generally can be heated to more than 400F without deformation.
- Powder is applied with electrostatics
- Typical voltage 80-100 KV
- Typical current 100-140 uA
Grounding the part is just as important as imparting the charge in powder applications. Transfer efficiency is increased as the part to gun distance is decreased due to there being less resistance. It can be hard with high voltage to get powder into deep corners and grooves without “bridging” over the feature lines. Certain application tricks and applicator settings can be used to help achieve a durable and glossy finish with powder coatings.
Transfer efficiency with powder can be as high as 97% due to recovery and reuse systems commonly used with powder. However, recovery systems are limited to only one color per booth, so for example, you may have a blue booth, a green booth, a red booth, etc. Needless to say, this can get quite expensive if you have more than a few choices of powder colors. However, if you only need to apply one color, like black for example, powder can be a very cost effective method of providing protection and beauty to your metal products. Durability can be superior with powder coated metals due to powder’s ability to be applied heavily or thickly without runs or sags.
There are energy costs associated with powder coatings that typically exceed that of liquid, especially urethane coatings. The high bake required poses some drawbacks.
Obviously, the energy impact must be considered, but also part mass. A metal part of a large mass will be slow to heat and slow to cool, not only introducing a large draw of energy, but potentially a massive slowdown in the operation. Because of this, large mass metal parts are often liquid coated.
Liquid Coatings is a rather general category for many chemical coatings technologies. Liquid coatings may be applied to a broader selection of substrates than powder coatings, such as wood, plastics, composites, concrete, masonry, steel, aluminum, and more. Typical liquid coatings may include urethane, enamel, acrylic, epoxy, polyester, polyaspartic, polyurea, and waterborne coatings. Air dry, low-bake, high-bake, DTP (Direct to Plastic), Primers, Adhesion Promoters, Reducer Blends, Mix-Ratios, 1K, 2K, ugh, …all the complicated terms, how can anyone be expected to keep up! With U.S. Paint it’s simple, tell us what you’re trying to achieve, and let us help educate and guide you to the best solution for you. Typically, our customers are trying to achieve very specific properties for coatings such as UV color fastness, cross-hatch adhesion, resistance to scratch, chip, and mar, chemical resistance, humidity cycles, impact resistance, etc. The substrate materials are very different in automotive and construction, and as you can imagine, so are the requirements for the liquid paint.
Whether enduring Florida sunshine and saltwater spray, or the punishing life of modern electronic mobile devices, liquid coatings are capable of performing to the highest standards in every industry.
Application types for liquid coatings:
- HVLP (High Volume Low Pressure)
- LVMP (Low Volume Medium Pressure)
- Typical voltage: 5-100 KV
- Typical current: 5-60 uA
- Rotary Atomizers
- Airless/Air Assist
- Roller Applied
- Brush Applied
- Squeegee Applied
- Dip or Roll-on
Liquid coatings often have greater VOC’s (volatile organic compounds) than powders due to their solvents. However, with EPA delisted solvents, low or no VOC formulations, and abatement systems, liquid systems offer superior application choices. No matter your industry or coatings requirement, call on your U.S. Paint teammates to carry you to the “Finish” line.