Paint guns come in two different feed types: gravity fed or siphon (pump) fed guns. When considering the type of paint gun you need for a project, you must consider the kind of paint you will use, as not all paint types are suitable. A paint gun operates by creating an vacuum to pressurize the paint then, as paint is applied, air and paint are forced out together creating a fine mist.
Physical Differences
A gravity fed paint gun generally means that the paint cup is on top of the gun. The paint naturally falls through the nozzle as you squeeze the trigger. A siphon or pump fed gun has the paint cup on the bottom of the gun and paint is pumped up through the nozzle as you pull the trigger. The siphon fed paint gun will need more pressure to create the paint spray as it is working against gravity to feed the paint through the gun.
Paint Weight
Siphon fed guns may choke when using heavier latex paints because the pressure needed to siphon them is too great. Gravity fed guns are popular because they can use anything from light stains to heavy latex paint. However the heavier the paint, the larger the gravity fed paint gun's cup will need to be in order to have enough of the paint mixture so it will not settle out. Gravity fed paint guns cannot use large amounts of paint at once as there is no way to keep a large amount of paint above a hand held paint gun.
Waste
Paint waste is a large concern, as it requires a greater clean up time and more paint to finish a job. A gravity fed paint gun eliminates this problem by having the cup on top. All the paint is fed through the nozzle with little to no waste. A siphon fed gun cannot use all the paint in its cup. As you use the paint, the straw can only pick up the paint in its vicinity. Eventually the paint will go below the straw's level and be left in the bottom of the cup.
Over Spray
Over spray happens when too much paint is sprayed onto the surface causing it to drip. Siphon fed guns are susceptible to this because the high-pressure spray is hard to control. A light hand on the trigger is necessary which may take a lot of practice to get used too. Gravity fed guns are easier to control because the pressure is constant and low allowing users to make fewer mistakes.
Saving Money
In the end, gravity fed paint guns will save you more money in paint, cleaning and saving you from costly mistakes in painting. However, for larger jobs and with greater practice, a siphon fed paint gun may do the job.
