How to select masking tapesSelect sandblast masking tape Thermal spray tape selection choice

Images credits: Dick Blick; Pro Stencil; Maxitape

 

Masking tape is a variety of adhesive tape that is recommended for the temporary concealment of surfaces not intended for a finishing process. Masking tapes temporarily protect areas from painting, soldering, blasting, spraying, coating, plating, and polishing while these procedures are administered to nearby surfaces. The composition of masking tape depends on the activity for which it is designed.

 

Masking Tape Operation

Masking tapes operate in the exact fashion as other adhesive tapes: a single-piece backing is wound around itself, which holds an adhesive on one side of the backing. Masking tape is applied to surfaces that the operator desires to keep in its existing condition while surface treatments occur in proximity.

 

Most masking tapes are applied by the use of a pressure sensitive adhesive; since most masking tapes are applied by hand, masking tapes are tearable and easily dispensed. Products are rated by the tackiness of the adhesive used (on a scale of 1—100), as well as how long the tape can remain before the adhesion hardens and becomes permanent. Tape removal should be executed as soon as the tape has outlived its usefulness to prevent the adhesive from leaving residue or damaging the surface it was meant to protect.  

 

Masking tapes find their most common usage in painting operations to contrast colors and components. Masking tapesare common for high-intensity processes, such as thermal spraying, shot peening, and electroplating, and these tapes find design variants for their unique jobs.

 

Masking Tape Production

Video credit: Science Channel via Youtube

 

Tape Adhesive

Since masking tape's intent is temporary, the removal needs to be residue-free. This limits the adhesive options for masking tape.

  • Acrylic

Acrylic-based adhesives reach their maximum adhesion almost immediately upon application, have adequate resistance, require no preparation, and have good sheer and peel strength.

  • None
Non-adhesive tapes, films, or laminates do not have an applied adhesive. These tapes are self-adhering and rely on a high coefficient of friction to remain adhered.
  • Rubber
Adhesives with a rubber-based chemical structure have highly flexible bonds that are based on butadiene-styrene, butyl, polyisobutylene, or nitrile compounds. 
  • Silicone   
Silicone adhesives and sealants have a high degree of flexibility and very high temperature resistance (600°F). While available as a pressure sensitive application, some silicone adhesives may require ventilation, or UV or EB radiation to cure. 

 

Tape Carrier

  • Ceramic
Ceramic-backed tape is appropriate for extreme-heat conditions, and is usually a proprietary mix of alumina-boria-silica fibers or some other ceramic textile.
  • Foam
Adhesive-coated polyolefin foams include an adhesive that is protected by a liner in the form of a tape, film or laminate.
  • Foil
Metal foil tapes offer high reflectivity and heat resistance. They commonly have aluminum, aluminum-reinforced, or lead backings. 
  • Glass
These are similar to cloth carriers, but are reinforced with glass or fiberglass particles to enhance heat resistance to over 300° F. 
  • Polyimide
Polyimide film maintains excellent physical, mechanical, chemical and electrical properties over a wide range of physical environments. Kapton® tape is made of polyimide film and a heat-resistant, silicone adhesive. Kapton is a registered trademark of DuPont Teijin Films. Polyimide films are very useful substrates for the manufacture of flexible circuit materials.  
  • PVC/vinyl
By using a vinyl carrier, the packaging tape has enhanced biological and chemical invulnerability, as well as more flexible workability. PVC is also relatively cheap. 
  • Paper
Paper backings are very common for masking tapes; they are inexpensive, easy to produce and dispense, and are often kraft, washi, or crepe paper. 
  • PET/polyester
Polyethylene teraphthalate/polyester carriers have high resistance to solvents, and have good aging and clarity characteristics. 
  • Fluoropolymer
A fluoropolymer backing will provide excellent chemical resistance, as well as water and stain resilience. The inert nature of these types of carriers prevents items from sticking to the carrier. Polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) are common carriers for adhesive tapes. 

 

Common Types of Masking Tape

Painter's tape is tape explicitly made to assist painters in the application of paint. The tape is used to prevent paint from being coated on different colored areas to create a contrast. It is frequently used on trim (doors, windows), and is usually denoted by color (blue, green, purple). Some painter's tapes are specialized for use with coatings with thick viscosity, such as lacquer and polyurethane. Other painter's tapes are meant for automotive painting applications, where adhesives are altered based on the area of placement.

 

Video credit: Ace Hardware

 

Plating tape is used to protect sensitive components from unwanted deposition of metals during electroplating, or the creation of metal oxide during anodizing. These tapes must withstand acids, chemicals, and extreme temperatures.

 

 Selecting plating tape

Image credit: Echo Supply

Abrasive blasting tapes mask components during sandblasting, shotpeening, or other coarse-media finishing process. A rubber or elastomer backing provides wear resistance to covered areas.

 

 Sandblasting tape selection

Image credit: eHow

High-temperature tapes are sufficient for brazing, soldering, and welding applications. This is particularly useful for processes like wave soldering, and this type of tape is often water-soluble and low-static. Brazing tapes use a brazing alloy layer on both sides of the tape, which are then covered with an adhesive and carrier.

 

 Wave soldering tape selection type

Image credit: 3M

Thermal spray tapes resist impingement and heat from plasma, wire arc, or oxyfuel spray processes. These tapes also have good wear resistances and release their adhesive easily.

 Thermal spray tape selection

Image credit: Maxitape

 

Masking Alternatives

Stop-off coatings and masking compounds are alternative resources to prevent finishing processes from overspray. Visit the stop-off coatings and masking compounds selection guide for more information. 

 

Masking Tape Specifications

Tape Dimensions

For tapes, there are two important geometrical aspects to consider, width and thickness. Length is unimportant because this is determined by the user at the point of application.

  • Width is the measurement across predetermined edges of the tape. Tapes can be cut by the customer to smaller widths.

  • Thickness is the distance between the two, flattened surfaces of the tape (carrier and adhesive). It is usually expressed in mils or thousandths of an inch and is measured under pressure with a gauge.

Masking wraps are produced in rolls or large cuts, which are then resized by the consumer.

 

Tape Features

  • Tensile strength is the maximum load the tape can withstand. Packaging tape strength ranges from a few ounces to hundreds of pounds, and is important for keeping items sealed.
  • Peel strength is the amount of force needed to separate two bonded surfaces.
  • Temperature resistance is the amount of heat the tape can be subjected to without compromising the tape's performance. Packaging tape typically does not have enhanced temperature properties, and packaging film has a molecular structure that aligns and tightens when heated.
  • Abrasion resistance is the level of scratch resistance and ruggedness of the tape.
  • Transparent products allow the transmission of light. A tape is rated as transparent if 10-point type can be read easily when the tape is applied directly over it.
  • Day rating is the estimate of time masking tape can be applied to a surface before the adhesive could potentially damage the substrate.
  • Weather resistant products are suitable for outdoor use and resistant to ultraviolet (UV) light, cold, heat, water or other weather conditions.

  • ESD control functions are useful in circuitry applications, and have conductive, friction reducing, or ionizing characteristics.

Tape Standards

In regards to general-purpose masking and function, the ASTM D6123/D6123M - 97 doctrine has established typical minimum quality standards for the functionality of masking tape. The ASTM was advised on the guidelines for tapes by the Pressure Sensitive Tapes Council, an industry trade association. Tape for electroplating purposes face an outdated government recommendation for quality, outlined in Federal Specification HH-T-0025. Other tapes have not received the same attention to quality. 

 

Resources

 

3M - 3M Masking Tapes; Specialty Masking Tapes

 

Wikipedia - Masking Tape