KTA-Tator, Inc.

About Us

Services

Careers

Trade Shows

News & Articles

KTA-TATOR, INC.
Corporate Headquarters
115 Technology Drive
Pittsburgh, PA 15275
Phone: 412.788.1300
Fax: 412.788.1306
E-mail: info@kta.com

Instrument Sales
1-800-KTA-GAGE
Lead Hotline
1-800-LEAD-OFF

Home

KTA Challenge #8
Answer - Roller Nap


Photograph 1 - Challenge microphotograph at 200x	Photograph 2 - Roller nap at 50x	Photograph 3 - Roller nap at 20x

Challenge 8 (Photograph 1) is a digital microphotograph (200x, taken in the KTA laboratory using a state of the art digital microscope) of roller nap embedded in a coating. Photographs 2 and 3 show the nap at reduced magnification. While it is common for roller covers to lose fibers during application, high quality covers with a core and fibers compatible with the coating being applied should be used to minimize the amount of loss. If the embedded nap is not completely wetted by the coating and sealed by the film, it could increase permeability to moisture or other liquids, potentially effecting service life. While nap in the film is typically not noticeable from a distance, if excessive, it can be unsightly when the surface is viewed at close range, and may call into question the care taken during application.

Roller covers range in diameter and length, with 1 ½" x 9" the most common. The diameter and length should be selected with consideration of the configuration of the surface being coated. The size also affects the amount of paint that the roller can hold. For example, a 2"x 9" roller will hold about twice the amount of paint that a 1 ½" x 7" roller will hold.

Roller cores are manufactured from a variety of materials with phenolic cores common for most industrial coatings.

The length of the nap fibers vary from ¼" to 1 ½". Longer fibers hold more paint, but will not provide as smooth a finish. Lengths of ¼" to ½" are common for standard industrial coatings and for painting smooth surfaces. Longer nap (3/4" to 1 ½") is used for coating rougher surfaces.

A variety of fibers are also available, both natural (e.g., sheepskin, lamb's wool, mohair), and synthetic (e.g., acrylic, nylon, polyester). Woven fabrics shed fewer fibers than knit, and will create a better finish when applying a glossy coating.

The coating manufacturer's application bulletins provide guidance on the appropriate roller to use for the product.

KTA can assist you with questions regarding coating application or for assessing the quality of application in the field. A variety of gages are also available from KTA for measuring coating thickness, both wet and dry, and for testing the continuity of the applied coating.

The majority of the answers were incorrect this time. Some of the incorrect responses included green algae on plaster, cracked coating on concrete with efflorescence coming through, coating delamination, and coating repair. A few people felt it was sandpaper, and one of the most unique answers was a potato chip. The winner, drawn at random from the correct responses was Tom Schwerdt of the Texas Department of Transportation.