Improving application and efficiency of your UV primer

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BY ANDREA HINDT

Although UV products have been used in the automotive industry since the early 2000s, their popularity seems to come in waves.

Initially not only were these products new, unproven technology, but a major hang-up for the end user was the need for a new UV light to cure the product. For decades prior, shops had become more adept at using IR curing lights to shorten dry times and increase throughput. Now this new product required additional cost to cure it along with safety precautions due to exposure of UV light.

Fast forward to today and enough time has passed that UV has found its place in our business. There are more UV curing light options than ever before. There’s also a wide variety of UV products in the market from all kinds of manufacturers. Those products range from primers to clear coats to spot putties. In this article, we will primarily focus on UV primers since they are the most relevant product in our business. I also prefer to focus on products designed by what we’ve come to address as “Premium Paint Manufacturers.” These products have good technical information available and oftentimes have a full paint system warranty associated with them.

The application process for UV primers is not too far off what we would consider standard; however, I strongly suggest reading your paint suppliers technical data sheet. This is to ensure you’re using the proper spray gun setup to achieve targeted film builds as well as flash times and proper cure times.

SATA has two fantastic options for spraying UV primers. The first being the SATAjet 100 B RP 1.1UV. This spray gun nozzle set has been specifically designed to spray UV products. Working closely with the paint manufacturers, SATA created a setup that will atomize the product fine and even to ensure an even film that is controllable for thickness. The superior material distribution throughout the pattern avoids thickness variations that can cause dark spots and lead to uncured product. As I mentioned prior, these products are slightly pigmented and will show a blotchy appearance if sprayed improperly or with inconsistent film build.

The second option that SATA offers is the SATAminijet 4400 B HVLP or RP. The benefits that come from spraying not only primer, but UV products through the minijet is profound. Again, check with your paint manufacturer for specific recommendations. The most common setups for spraying UV primer with the minijet 4400 are the 0.8SR or the 1.0SR. Both options offer unparalleled atomization and material distribution throughout the pattern. Additionally, the SATAminijet offers the lowest amount of overspray from any paint gun. That feature alone allows a technician to utilize less material as well as less masking. Please be sure to check out the SATA by DanAm Company YouTube channel for demos of this process.

Since UV products are photochemically reactive, meaning they begin to cure as soon as they are exposed to natural daylight, it is important to utilize an opaque spray gun cup.

The SATA RPS cup system offers a UV cup option, and is available in one size 0.6L. Utilizing the black UV cups for spraying UV products ensures the product has not been exposed to light that could potentially alter the characteristics of the product and its performance. With the spray gun cup preventing light exposure, you can now pour UV primer in a cup, mount it to either the to your spray gun and spray all day. The product will have a much longer pot life than traditional primers, allowing for no wasted material going into the waste drum.

Other products that help when spraying UV is a black rubber air cap cover that keeps light from hitting that little bit of product left on the tip of the needle. Using one of these caps between coats and while the spray gun is hanging between repairs ensures product and spray gun performance. That little drip on the needle can harden in daylight and end up being dirt in the repair you’re priming.

A couple things to know about UV primer characteristics.

• I like to group UV products into two categories. The first being true UV cure technology that requires a UV light with a specific spectrum of UV light to cure. These products are most commonly found in Ready To Spray (RTS) form. They typically require a quick shake or stir before pouring into your RPS cup. The second being what can be referred to as “dark cure” UV products. Dark cure UV products are also cured with a UV light for maximum speed, but areas where the light does not hit will cure in time. Those products often require a catalyst or hardener addition prior to spraying them.

• Most UV products are semi-transparent. Being as they are cured with light, the product must have a decent amount of transparency to allow the light to travel down to the bottom of the film.

• UV products still have solvent that will need to evaporate out of the film during flash times and the curing cycle.

• Due to the footprint on the UV curing light, UV products are typically focused on small, spot priming repairs. Usually, the maximum size repair is around a 12”x24” area. Larger footprint portable lights are available as well, all the way up to UV cure spray booths.

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