How to use UreChem Chemfill 2K Primer Surfacer UP-61

UreChem Automotive Paints | HS 2K Polyurethane Primer Surfacer | UP-61

Today's topic is the proper use and application of our Chemfill 2k Primer Surfacer UP-61. Two-component or 2k epoxy primers such as Chemfill 2K HS Primer Surfacer, offer best-in-class filling & sanding properties to provide a smooth surface ready for painting.  Chemfill is recommended over properly prepared automotive surfaces including bare steel aluminum, fiberglass factory paint finishes, body fillers, & many common automotive plastics.

Chemfill will adhere to properly prepared bare steel and aluminum and provide some corrosion resistance however the use of ep-21 epoxy primer directly to properly prepared materials prior to application of Chemfill provides a system with substantially better corrosion resistance than any direct metal urethane primer.

Chemfill is for use only in areas that do not require Low VOC products most of the united states does not require a low VOC product but some areas do such as most of California, Maryland, Delaware, and potentially other areas as regulations evolve. Always check local regulations before purchasing.

Best Spraying Conditions

As with any automotive finish, proper painting conditions are important for obtaining the best results. It's best to paint in temperatures above 60°F part temperature and at least 70°F paint material temperature. Keep in mind that the conditions outside are brought into your booth through your booth intake.

Moisture should be a concern when applying automotive finishes. So, unless your paint booth has the ability to heat your parts well above the dew point, you should not paint when raining, dew on the ground, or fog in the air. Parts painted at temperatures near the dew point can easily condensate thin layers of moisture which are often not visible on the part or in the paint film itself but can cause failure to the finish.

Low humidity Blue sky days are the best conditions for painting provided you can get your part temperatures above 60 F. Once you have your parts ready to paint and the conditions are good for painting, start by wearing the appropriate personal protective equipment and only use this product in areas that are free of ignition sources such as heat, sparks, or open flames.

Safety & Mixing Procedures

Chemfill UP-61 is very high in solids at over 70 percent and some of those solids will slowly settle over time.  Start by mixing well prior to activating. Hand stirring with a paint stick is generally sufficient to re-incorporate any solids that may have settled to the bottom over time. Be sure to scrape the bottom of the can to lift and stir any solids back into a smooth consistent state. Chemfill UP61 can be mixed 4:1 by volume with UreChem's UA-40, 41, or 42 Series Activator & used without reduction when using large fluid tip primer guns with 1.8 to 2.2-millimeter fluid tips

However, for best results, we recommend mixing four 4 1:1 by volume with activator and reducer. Chemfill mixed 4 1:1  applies easily from a 1.3 to 1.6-millimeter fluid tip and dries to a smoother finish that requires less sanding than unreduced mixes applied from a large fluid tip primer guns also applying the product mixed four one to one reduces the chances of solvent entrapment in thick films and the same build can be achieved with an additional coat maybe two.

UreChem mixing cups have a 4 1:1 column to easily mix and can fill accurately. If you are new to paint mixing cups we go into this in more detail with our video on How To Use UreChem Paint Cups.

Spray Gun Configurations

After adding all ingredients, mix well with a paint stick, scraping the sides and bottom occasionally to ensure it all gets mixed properly. At this point, you're ready to strain it into your paint gun.

For best atomization, spray pressures should be set to:

22 - 30 psi

at the trigger for gravity-fed HVLP Guns

40 - 55 psi

For siphon fed guns for reduced pressure guns refer to the manufacturer's recommendations

Don't forget to check the volume adjustment knob on your spray gun each time you use your spray gun.  It's a good practice to screw the fluid adjustment clockwise all the way to hand tight then count the rotations as you turn it counterclockwise to open it up with Chemfill UP-61 4 turns out from hand tight is generally a good starting point.  This will vary depending on your particular setup.

Spraying A Test Panel

Test spray and check your pattern. Your spray pattern should be a tight and uniform ellipse shape. Once you have a good spray pattern, spray a test panel to make sure the product flows well and you're happy with your settings.

Now apply two to three medium wet to wet coats with fifty percent overlap a 6 to 8-inch fan pattern at approximately 6-inch standoff distance from the surface is a general recommendation. Be sure to allow fifteen minutes flash times between each coat to avoid solvent entrapment. After your last coat, clean your gun immediately with a suitable cleaning solvent, lacquer thinner, acetone, or MEK. Check local regulations for compliant gun cleaner options.

Flash Times & Spray Gun Cleaning

Chemfill UP-61 requires two hours at 75 degrees Fahrenheit cure time before sanding.  Check the provided material data sheet of the next layer you will be applying.  For proper finished sanding, grip before proceeding.

Be sure to check out the Tutorial video below!