Spray fine finishes are often considered an art within the finishing industry. Many old school painters swear only by HVLP technology and even in today’s time with turbine HVLP units many new schooler agree. Then, less credible, you have the guys that say alkyd/acrylic or modified acrylics lay down so smooth that you do not need to spray them. Even the best paints simply don’t lay down enough to compete with ANY spray equipment properly applied fine finish. That is why this article address’s spray finishing equipment.
The best spray finish is the question of the day. Cabinet Painting has become so popular and which spray system gives the best finish is something I get asked constantly. At Grants Painting our kitchen cabinet painting competitors are offering many different options that produce similar results. There are factors that will change the results of any spray finish depending on factors you can control and factors that are less controllable. Some of these include, temperature, dew point, humidity, ventilation, primer, topcoats choices, skills of the applicator and all sizes of debris.
Environmental Factors On Spray Finishes
Humidity and ventilation are huge factors for how the paint finish dries and therefore levels out to the durable and smooth finish that you want. This is a complicated issue and requires some knowledge about collision suspensions, surfactants, latent solvent profiles and paint coalescence. However, those things are why most paint manufacturers suggest a strict 50% relative humidity at 77 degrees Fahrenheit.
%50 relative humidity at 77 degrees
The paint manufactures recommendations are great to follow, but actually understanding the science behind it will allow you to do more in any environment with both HVLP and airless spray technologies. Humidity and temperature change the dry time very dynamically, this is the biggest factor to how your paint will perform. The same paint in the same color dried at very different temperatures will also have very different finishes AND levels of durability.
Cool temperatures and too quick of a dry time are poison for any paint film applied in any way.
Topcoat and Primer Choices
Primer selection is another issue, it will change the performance of both the durability and the finish. Mostly the changes are in the fact that dry time will be heavily influenced by the primer choice relative to the surface.
Topcoats contain a solvent profile and surfactants. When adding anything to paint you will be changing how the paint dries so this needs to align with your environmental conditions. This matters especially with the choice between HVLP and airless as many lower quality HVLP systems require thinning to spray properly. Thinning the paint changes the dry time and therefore may compromise durability if done improperly. Most painters do not understand the science of paint well enough to thin the paint properly with the correct solvent/surfactant mix. Higher quality turbine HVLP systems can spray with very little changes to the viscosity through thinning. The Titan CapSpray 115 that we use, is a 6 stage turbine HVLP unit that has amazing abilities to spray most paints with little or no thinning.
New Technologies in HVLP and Airless Spraying Compared
Airless spray technology has increased and therefore made airless sprayers a competitor in the fine finish spray industry. Graco now has Low Pressure Fine Finish tips. These tips combined with a quality airless unit that keep a steady pressure instead of a pulsating pressure, like most paint sprayers are priced at under $1200. A good airless sprayer and a low pressure fine finish tip can supply the same finish that an HVLP can with the help of a quality topcoat and proper environmental conditions. The issues arise when you cannot control the environment though proper ventilation, heaters, humidifiers, de-humidifiers and solvent/surfactant mix adjustments. The lower pressure of the new Graco tips will eliminate orange peel commonly caused by the pressure and speed of larger particles smacking into the surface and bouncing/splashing on a micro level.
HVLP now has turbine units that are portable and also eliminate the issue of moisture in the air supply allowing for the standard conventional HVLP problems to be eliminated. HVLP’s will always be able to give a smooth finish with an experienced spray guy. However, the cheaper units, generally under $1000 will always need thinning which almost always will decrease durability.
Debris Of All Sizes
Debris will ruin any finish. Very small debris can cause haziness and fisheyes that are not obviously caused by debris. Large debris will clog either system. Airless systems are larger and the fluid section is difficult to keep free of debris as normal cleaning and maintenance are more difficult and sometimes neglected. Larger debris particles are also crushed and made into many smaller particles that will contaminate the larger fluid section and therefore, will cause more issues with airless sprayers. If you cannot control debris then HVLP is your only option.
Short Answer For The Best Finish
The short answer is that HVLP is much harder to operate but is more fail safe in providing a top quality finish, however, many applicators do not have the knowledge or patience to make the finish visually appealing and durable as with an airless sprayer. Airless sprayers can give the same top quality finish at a much better production time and effort with better durability, however, topcoat choice and environmental factors have to be controlled perfectly to achieve this. Coats that will be sanded completely are better applied with an airless spray system as smoothness is achieved with sanding regardless of spray equipment.