Establishing a Spray Fan
28 February 2022

There are steps that can be followed to establish a spray fan. Perform the appropriate steps for your gun in the order given. Use the steps in this section that are applicable to your spray fan.​

Set Up the Gun

  1. Use a little red grease on the O-rings and threads of the material spray tip, catalyst tip, and retaining ring.
  2. Install the material spray tip into the front of the gun block.
  3. Install the catalyst tip over the material spray tip, using caution not to damage the O-rings on the front of the gun block.
  4. Install the retaining ring to secure the catalyst and material spray tip in place.
  5. Make sure all hose connections are tight.

Establish a Fan Pattern

Magnum Venus Products spray equipment provides one of the most efficient methods of quickly applying material to a surface or mold. To make the most of our low-pressure pumping systems and airless internal mix guns, you must understand how to adjust the system for maximum efficiency.

Note: Because conditions and material vary widely, we cannot provide specific instructions. We do offer guidelines and tests so that you can tune your equipment to meet your specific needs. The basic idea is to use just enough pressure to the powerhead to establish the spray fan and no more.

  1. Lay out a strip of test material such as paper or cardboard.
  2. Adjust the main pressure regulator until the operating pressure is 20 psi (1,4 bar).

Note: Operating pressure is the air pressure used to operate the resin pump. The gauge and regulator are usually labeled “Main Pressure” or “Pump Pressure”.


  1. Moving lengthwise along the test strip, begin spraying a short test fan.
  2. If the first test shot had an established fan pattern, flush the gun into an appropriate container, back off the air pressure by 5 psi (0,4 bar), then shoot another pattern.
  3. Repeat step 9 until the unit no longer produces a fan, then increase the operating pressure until there is just enough to form a soft-looking fan.

Note: It is unlikely that 20 psi (1,4 bar) will be sufficient pressure to establish a fan pattern.


  1. If the pressure was not adequate to form a well-defined fan pattern, flush the gun and then increase the main pressure by 5 psi (0,4 bar) and do another short test spray.
  2. Repeat step 11 until a well-defined spray pattern is obtained, then perform step 9 to obtain a soft-looking fan.

Adjust the Fan Pattern

  1. Adjust the pattern according to the table below.


What to look for in test shots:
If you see Cause / Description Adjust as follows:
One narrow stream (A) Operating pressure is very low for the material you are using Increase the operating pressure
Increase material temperature
Use a smaller nozzle size
Three heavy fingers (B) Horns are beginning to develop, but the operating pressure is still very low Increase operating pressure
Increase material temperature
Use a smaller nozzle size
Middle of the stream is wider (C) Middle of the stream is still not the full width it should be for the nozzle in use Increase operating pressure

Increase material temperature


The pattern is at or near full width (D) There are well-defined fingers, however there is little or no white frothing (air bubbles) in the center of the spayed material
Note This pattern is usable for an experienced operator
Slightly increase operating pressure
Slightly increase material temperature
The pattern is full width (E) The fingers are well-defined. A small amount of frothing appears in the sprayed material but disappears in less than 2 minutes This is considered the best general set of conditions for the fan pattern. Make note of the main pressure and material temperature
The pattern is too wide (F) The fingers are poorly defined. Heavy misting is seen and smelled and there is significant overspray. The heavy white frothing does not disappear within 2 minutes
Note This is the most common mistake seen when running MVP equipment
Back off the pressure until the fan pattern fails, then add pressure in 5 psi (0,4 bar) increments to get the pattern back


  1. Use the following worksheet to make notes of and track the optimal conditions noted during adjustment.

Spray Fan Notes