Choosing a Gel Coat Spray Guns – A Complete Guide
Gel coat is a unique material due to its heavy viscosity, requiring a catalyst, and its environment requirements. To properly spray gel coat having the right spray gun is critical. The primary types of spray guns available to spray gel coat include LEL, AAA, and conventional spray guns. LEL offers a variety of features that should be considered. This article will cover the different technologies to spray gel coat, the benefits and drawbacks of each, and how you can decided which may be right for your gel coat spraying needs.
LEL (Low Emission Laminators) Gel Coat Spray Guns
LEL gel coat guns work by mixing the gel coat and catalyst from two different streams. When the streams collide a fan is created which is then directed at a mold so that your gel coat can be smoothly applied. Since LEL doesn’t apply shaping air to the materials but rather relies on the two fluid streams impinging on one another to create a fan. By not introducing air into the material LEL laminators are highly efficient and provide the least amount of over spray of the different gel coat spray gun options. They are typically more expensive and therefore are typically used in high production gel coat spray applications. Since they use little or no break up air when spraying they are typically not effective at applying gel coat outside of a mold process. So if you are primarily re gel coating over an existing gel coat or performing field repair work you will typically want to consider one of the other options.
The second factor to consider with an LEL gel coat gun is whether the materials will be mixed internally or externally. The internal mix LEL gel coat spray guns offer the most reduction in waste but cannot always disperse and lay out gel coat as smooth as an external mix LEL gel coat spray gun. The external mix LEL gel coat spray guns can tend to create slightly more overspray compared to the internal mix option. However due to the properties of gel coat when it is introduced into a mixer (like it is in an internal mix gel coat spray gun) it can tend to result in a rougher final finish. Most of the time if the spray gun is for gel coat only it can be wise to consider an external mix gel coat spray gun as having a smooth gel coat is typically the top priority with gel coat application in molds.
AAA Gel Coat Spray Guns
Air assist airless gel coat spray guns use high fluid pressure against a tip along with a small amount of air to properly atomize gel coat. The atomizing air helps to better break apart the material beyond what the fluid pressure against the tip alone can achieve. Since fluid pressure is the primary way material is delivered and atomized it is quicker than air spray versions of spraying gel coat. The fine break up along with relative speed of spraying makes air assist gel coat spray guns well suited for larger scale repair work involving gel coat. The main downside is that because the material is atomized it will tend to produce a slight bit more over spray than LEL gel coat spray guns. Air assist gel coat spray guns may not meet MACT compliance rules either.
HVLP Gel Coat Spray Guns
HVLP Gel Coat Spray Guns are similar in transfer efficiency to Air Assist Airless Gel Coat Spray Guns. However, due to their use of air instead of fluid pressure and air, they tend to be slower than an Air Assist Airless Gel Coat Spray Gun. Due to their reduced speed of spraying HVLP gel coat spray guns are often used for smaller touch up gel coat spraying work. You will have the choice between a HVLP gun where gel coat is mixed prior to putting it into the gun or one that allows for mixing of the catalyst after the material is sprayed. For larger repair jobs a gel coat spray gun that mixes after the material is sprayed would be a better solution.
Conventional Gel Coat Spray Guns
Conventional spraying relies on higher air pressure (compared to HVLP) when trying to atomize a material. Due to the higher pressures that a conventional spray gun uses, it is only about 30% efficient at applying gel coat to a surface with the rest of the material becoming waste. This makes conventional gel coat spray guns more wasteful and often less ideal. The main benefit is that they are very forgiving when it comes to spraying because air pressure can just continue to be increased until you get the spray pattern that makes sense for your job. They are also designed primarily for use with small touch up gel coat spraying work. There are a few options for conventional gel coat spray guns. The 2100GW spray gun offers a catalyst mix cup that is mounted next to the nozzle where the catalyst is then mixed as the gel coat is sprayed. Other options include those that everything is mixed internally or externally but can handle slightly higher volumes of catalyst like the 7n Spray Gun.
Ultimately a proper gel coat spray gun will significantly improve your gelcoat application. If you need MACT compliance and/ or are in high production environments and using a mold the LEL laminators can make a lot of sense. For large repair work it can often make sense to consider the air assist airless gel coat spray gun. Finally, for smaller jobs a basic air spray gun may be all that is needed. If you need further assistance knowing which gel coat spray gun may make sense for you feel free to contact us or view our selection.