Spray Techniques – Configurations

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Painting Inside Corners

When spraying corners the gun should be aimed into the corner, spraying along the corner, rather than spraying back and forth across the corner.

To avoid double coating the same area, use horizontal strokes to spray the area adjacent to the corner. Spray each side of the corner separately. A vertical pattern is often used.

Outside Corners

To spray the outside of a corner, a straight-on method can be used. The adjoining surfaces are then banded.

Small/Vertical Flat Surfaces

When spraying small, vertical flat work piece configurations, the banding technique is used. Using a horizontal pattern, band the edges of the part. After banding the edges of the part, finish the part with horizontal strokes. First, spray the Class B side of a work piece (the side that will not be finished), then spray the Class A (finished) side. If there is any overspray turbulence, it will not appear on the Class A side of the work piece.

Long/Vertical Flat Surfaces

Spray long vertical flat surfaces with horizontal strokes in sections from approximately 18″ to 36″ wide. With practice, you will find the distance most comfortable to your needs. As on small vertical flat parts, use the same banding technique on each end of a long vertical flat part. Use the same triggering technique as with a smaller panel, but overlap each section approximately four inches.

Level Surfaces

When spraying a level or horizontal surface, always start on the near side of the part and work to the far side of the part: this technique allows the overspray to fall on the uncoated work. Some gun tilt will be necessary.

Round Parts

Small cylinder shapes, like furniture legs, are best sprayed with a narrow spray pattern, using three vertical strokes. A vertical pattern and stroke can be used, but the gun movement must be quicker to prevent sags and runs.

Spray smaller or medium diameter cylinders with lengthwise strokes. Spray large cylinders like a flat vertical surface, only with shorter strokes.

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Spray Techniques – Gun Movement and Position

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A good spray pattern indicates that the paint or coating is completely atomized and distributed evenly on the surface. Several techniques help determine the quality of the spray pattern and the quality of the finish.

  • Adjusting the pressure
  • Aiming of the spray pattern
  • Movement of the spray gun
The following techniques ensure a long-lasting quality finish

Adjusting the pressure for spraying

 

It is best to spray at the lowest pressure that completely atomizes the coating. The pressure control should be set at a low-pressure setting and slowly increased until the paint is completely atomized. If the spray pattern has fingers or tails, then the pressure should be increased.

 

Aiming the Spray Pattern

The spray gun should be held approximately 12 inches (30.5 cm) from the surface, and aimed straight (both horizontally and vertically) at the surface.
Extremely large tips will require you to move further away to achieve a good spray pattern.
The spray gun should move across the surface with the wrist flexed to keep the gun pointed straight at the surface. “Fanning” the gun to direct the spray at an angle will cause an uneven finish.

 

Triggering Technique

The spray gun should be triggered after beginning the stroke (also called the lead stroke) and released before ending the stroke (also called the lag stroke).
The gun should move during both the trigger squeeze and trigger release. This technique prevents blotches of thick coating at the beginning and end of each stroke.

Overlapping Technique

This technique ensures that an even amount of coating has been sprayed onto the surface. The spray gun should be aimed so that the tip points at the edge of the previous stroke, overlapping each stroke by 50%. To maximize efficiency when spraying on broad, open surfaces, like ceilings and bare walls, the outside edges of walls should be sprayed first. The middle can then be sprayed quickly, requiring less precise strokes.

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The basics of Airless Spraying – Advantages of Airless Sprayers

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Advantages of Airless Sprayers

Airless sprayers provide an easy and economical way to apply coatings. Professional contractors prefer to use airless sprayers for several reasons, the most popular being:

Speed—airless spraying is faster, thus, more jobs can be completed in less time, using less labor. Airless spraying is up to 10 times faster than brushing or rolling.

Quality—airless sprayers produce an even coat of paint on all types of surfaces, leaving a consistent and high quality finish.

Versatility—airless sprayers can be used for a wide range of coating materials, including interior and exterior jobs, and can easily be transported from job site to job site.

 

Research conducted by the Painting and Decorating Contractors of America (PDCA), an association of painting contractors and related industry professionals, indicates that airless spraying can save painters between 50% and 75% of their painting time. Airless spray is:

• At least 10 times faster than brush applications
• At least 4 times faster than roller applications

Using a brush or roller application might seem cost-effect ive in the short-term,but in the long-run labor can cost at least twice as much!

 

Airless Spray for Uniform Coverage

It is important to consider how much faster spraying is compared to other methods. Equally important to your customer is how spraying gives a consistent quality finish, even over rough surfaces.

Airless spraying allows you to:

Finish jobs quicker
— Finish within short weather windows
— Stay on a job site from start to finish, saving set-up labor
Complete more jobs with less labor (fewer people headaches)
Provide a consistent mil build so coatings perform better
Apply a smooth quality finish

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The basics of Airless Spraying – Coatings

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Coatings

Architectural coatings are primarily decorative coatings used to coat anything from homes to commercial and industrial buildings.

Protective coatings are primarily corrosion control coatings used to coat anything from bridges to water towers, preserving concrete and steel. Often these coatings are two-component materials.

The majority of coatings are sold at paint stores, generally to professional painting contractors.

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Virtually every coating contains four basic components:

Binder, Resin, or Polymer—holds together the other components prior to application and forms a protective film on the surface (the
surface is also called a substrate) to which the coating is applied. Binders can be oils, varnishes and proteins.

Pigment—fine solid particles that hide the surface providing decorative colors and sometimes corrosion resistance. Raw umber, a type of iron ore, is used extensively as a pigment and is olive green in color.

Solvent—helps the flow of the coating material and aids in application. For example, water is a solvent for sugar. However, in many coating formulations, a chemical referred to as a solvent, may not be dissolving anything, but simply diluting or thinning the formulation.

Additives—in general, manufacturers put additives into coatings for one or more reasons, including aiding in manufacturing, enhancing application characteristics, or improving the properties of the coating once it is cured. For example, some additives help prevent mildew from forming once the coating has cured.

Paints and other coatings are rated by the volume of solids they contain. While virtually everyone in the architectural coatings industry refers to the “low,” “medium,” and “high” solid content of coatings, there are no set amounts or limits placed on these categories. A typical set of values for coatings is:

• Low Solids = 20-30% solids
• Medium Solids = 30-50% solids
• High Solids = Up to 100% solids

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