Case sealing

Tapes

Gummed tapes

Gummed tapes are water-activated. They will adhere satisfactorily to all packages made from paperboard. They will not work well on metals or plastics. If "H" taping is used, and the tapes manufactured from hard-sized Kraft paper and efficiently applied, they should provide reasonable moisture and water-resisting properties, adequate for normal transport hazards. Due to environmental pressures, Kraft paper gummed tapes have gained in popularity, recently. For further details please see Reinforced gummed - <ASTM 1974> Section 5.3.1

Pressure-sensitive tapes

Pressure-sensitive tapes are already activated and will adhere satisfactorily to packages or containers made from paper, paperboard, metal, glass or plastics. They are based on Regenerated cellulose film, Cellulose acetate film, Polyvinyl chloride (PVA) film, Fabric and Moisture-resistant paper. Such tapes need only the application of pressure to cause them to adhere to almost any surface. Apart from seeing that the surface is free from dust, oil, grease or moisture, no special preparation before application is necessary. For further details please see Pressure Sensitive Plastic - <ASTM 1974> Section 5.2.1.  Clear tape is often to be recommended for aesthetic reasons. Cases may be in different colors such as Kraft or Mottled White. Labels and other markings that may be near or under tape will still be legible. Difficulties in tape application or cutoff will be less visible with clear tape.

Polypropylene tape recommendations:

Plastic Tape Spec

Minimum width: 2" (50mm)
Total thickness: 2.5 mil minimum
Tensile strength: 30 lb./in minimum

Heatfix or Thermo-sensitive tapes

Thermo-sensitive tapes are paper or fabric based and heat activated. They will adhere satisfactorily to packages or containers made from paper, paperboard, metal, glass or plastics. Such tapes, once activated by heat, need only the application of pressure to cause them to adhere. They are not used frequently in the corrugated field.

Tape Specifications

Case sealing tools and equipment vary and a variety of paper reinforced and pressure sensitive plastic tapes are found in common use. These may be specified interchangeably so long as a consistent type of tape is used on each box and from box to box.

The following table aids in the selection of tape width and application pattern on cases based on length of seam and weight of package. Longer seams require wider tape to accommodate greater variation in position, and greater deflection of joined panels across longer spans. Concentrations in weight against a seam also indicate variation in the straight seam application to an "H" pattern application. ASTM D1974

Tape Width / Pattern as a Function of Weight and Length

Imperial Units Length <16" (405mm) Length 16" - 23.9" (405-609mm) Length >=24" (610mm)
<10lbs (4.5Kg) 2" (50mm) 2" (50mm) 3" (75mm)
10 - 19.9lbs (4.5 - 9Kg) 2" (50mm) 2" (50mm) 3" (75mm)
20 - 29.9lbs (9.1 - 13.5Kg) 2" (50mm) 3" (75mm) 3" (75mm)
30 - 49.9lbs (13.6 - 22.5Kg) 3" (75mm) / H 3" (75mm) / H 3" (75mm)
>=50lbs (22.6Kg) 3" (75mm) / H 3" (75mm) / H 3" (75mm) / H

Width Conversions

U.S. Customary inches Metric mm Nominal mm
.5 12  
.75 18  
1 24 25
2 48 50
3 72  

Patterns

Closure Method 2B1 - <ASTM 1974> Section 6.6.2.1 – calls for 2" (50mm) pressure sensitive film backed tape to be applied over the center seams of the box and continuing at least 2" (50mm) onto the ends of the box. A variation of this method, determined by the table above, calls for 3" (75mm) tape to be used with the tape continuing at least 2.5" (60mm) onto the ends of the box.

Tape closure method 2B1

Closure Method 2B7 - <ASTM 1974> Section 6.2.2.7 – calls for 2" (50mm) pressure sensitive film backed tape to be applied over the center seams of the box and continuing at least 2" (50mm) onto the ends of the box. 4 additional strips shall be applied over the seam formed by the edges of the outer flaps and the end panels and extend to within Ÿ" (20mm) of the corners of the box.

Closure Method 2B7

For details of sealing machinery please click here.

Other Pack Sealing Methods

Strapping

Steel or Plastic strapping are often used for: Bundling, Palletizing, Unitizing, Reinforcing, Closing and Bailing. Polypropylene or Nylon strapping is what is most commonly used for pack sealing. The advantages are a strong and secure seal, however, it lacks ascetic appeal. However, when used with cases strapping can be very useful for tamper evidence and is particularly good when used on multiple depth cases, that can be difficult to deal with using standard gluing and taping machinery.

Stapling

King size staples are also used for sealing corrugated cases. These large performed staples are clinched on a retractable anvil, thus enabling the case to be closed after it has been packed. The main advantages are: economy and speed of closure, security and efficiency - no problems with storing pre-sealed cases or drying time. However, they are less suitable for sensitive or food uses.