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When spraying paint with a compressed air spray gun, whether gravity feed or siphon feed, conventional or High Volume Low Pressure (HVLP), it’s important to have the gun set up properly for the job. What you are painting is important to a certain extent, but more import is what you are painting with.
For example, if you are painting a small panel, or a motorcycle gas tank you can use a gun with a smaller spray pattern than if you are painting the side of a van. You can still use the big gun for a small project, but it is going to be more wasteful and messy. You can use the small gun for a big job but it’s going to take a lot longer to do it.
Moe important to the quality of the job you are doing is using a gun with the right size fluid tip and needle for the paint, primer or whatever else you are spraying. Most guns have the option of several different sized spray tip openings, with a matching needle for each one. Eastwood carries a selection of popular sizes for the guns they sell. As a general rule of thumb, thicker material, like high build primers use a bigger opening, while thinner liquids use a smaller tip.
Often times the paint or primer will come with recommendations as to how to spray it. Usually the instructions that come with the gun will have a handy chart too. Here’s what Kevin Tetz and Eastwood recommends for the Concourse HVLP gun.
For spraying clear coats on small parts and projects, a 1.2mm tip. For spraying a whole car a 1.3mm tip is recommended. The 1.4mm tip is perfect for base coats and metallic as the droplet size allows the particles to self-orient to eliminate streaking and mottling. The 1.8mm is at the upper end of sizes for urethane primer surfacers, and the minimum size you want to use for a poly-urethane primer surfacer, which can use up to a 2.2mm.
Here are some common tip sizes and recommended usages:
0.5-1.0mm – These are very common in detail spray guns because they provide a much smaller pattern compared to a larger tip on a full size gun. Also used for thin dyes and stains.
1.2mm, 1.3mm – Good for clear coat and thinner base coats. Spraying clear with a 1.2mm will take longer because the tiny hole doesn’t flow much fluid through it but will give you a very fine finish. The 1.3mm is a great general clear coat tip, also thinner base coats, waterborne and single stage paints. Too thick of a paint won’t flow well through this size though.
1.4mm – Great all-purpose size. Works well with most base coats, and even thicker clears. This size is the closes to a universal tip as it comes. When in doubt it’s a good place to start.
1.5mm, 1.6mm – Versatile tip for base coats and single stage paints. Thinner paints run the risk of orange peel though because they will not atomize correctly. Also a good choice for lacquer paints.
1.7mm, 1.8mm –1.7mm is the smallest size you should use for most types of primer, not a very common size but currently offered on the Eastwood Concours LT Gun. Typically 1.8mm is recommended for most primer surfacers. Also the smallest size if you are shooting latex paint, not that you would do that with your good HVLP gun.
2.0-2.3mm – High build primers and other thick materials. Avoid spraying and base, single stage or through these size tips, it will not atomize correctly and give a poor result.
If you still are unsure what sizes you will need, Eastwood makes it easy by offering our Original Concours and Concours Pro HVLP paint guns in sets that come with multiple sizes. Purchasing a set like these will allow you to spray all types of paints from the same gun, making it easier while saving you money.
There you have a rundown of the common sizes of fluid tips for the HVLP spray gun and what they are for, with the most common in red. If you just remember thinner smaller, thicker bigger, it’s pretty intuitive. With fancy paints like pearls and metal flakes, you may have to go smaller and larger respectively for them to come out really well, but the only real way to find out is with practice, lots of practice.
Check out the Eastwood Blog and How-To Center for more Tips and Tricks to help you with all your automotive projects. If you have a recommendation for future articles or have a project you want explained don't hesitate to leave a comment.