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Technical Bulletin

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On surfaces with a light oily film, or other light contamination, the 50:50 IPA/water solution is usually
adequate. Where heavy oils or grease are present, a “degreasing” solvent such as 3M™ Prep Solvent 70,
3M™ Citrus Base Cleaner, mineral spirits, naphtha or similar solvents are suggested to cut the oil. This
should always be followed with an IPA/water cleaning to help ensure that any residue or film is removed.*

Abrading a surface can serve several functions:
• Remove heavy levels of dirt or oxide from metals or paints (e.g. galvanized steel).
• Create additional surface area that can increase adhesion.
• Smooth a surface to obtain more flatness, allowing improved contact area.

Abrasion often helps adhesion to paints and plastics. When abrading, it is important for tapes to have a
finely abraded surface. Very small scratches in the surface, generated with circular motion rather than
straight-line motion, are most desirable. A surface with many micro-scratches in it can have up to 40%
additional available surface area, translating to higher ultimate strength and greater initial adhesion.
Scotch-Brite

®

Hand Pads (such as 7447 Maroon or Heavy Duty Green) are good for achieving the right

level of abrasion. Tools such as a power palm sander will assist on large jobs. Avoid grinding a surface
with coarse abrasive materials, since they may create too rough of a texture for the adhesive to
adequately flow into the surface. Always clean the surface with the IPA/water solution or additional
methods previously described, and be certain that all loose particles are removed prior to bonding.

Exceptions to these abrading guidelines are 3M™ VHB™ Tapes 4932 and 4952, as they typically
perform best on smooth glossy surfaces and abrasion may reduce the bond strength.

*Note: These cleaner solutions contain greater than 250 g/l of volatile organic compounds (VOC). Please consult your
local Air Quality Regulations to be sure the cleaner is compliant. When using solvents, be sure to follow the manufacturer’s
precautions and directions for use when handling such materials.

Priming a surface can significantly improve initial and ultimate adhesion to many materials such as
plastics and paints because of their low surface energy or the additives they may contain. A primer
creates a new surface for VHB tape to adhere to and can also create a layer that may impede the
migration of additives that may be present in a material. It is important for the user to determine the
suitability of the VHB tape, the adhesion promoter and the application process.

Rough, porous or fibered materials such as wood, particleboard, cement, etc., have an open surface and
require sealing to provide a unified surface for tape bonding. Common sealing materials would include
paint, varnish or other hard surface coatings. Fast drying 3M™ Rubber and Vinyl Spray 80 can also be
used to unify the surface and improve the tape bond.

Glass, stone, ceramic or other siliceous materials are hydrophilic (water-loving) by nature. Normally, the
hydrophilic nature makes pressure sensitive adhesive bond durability susceptible to change under high
humidity or exposure to moisture. In basic terms, water vapor can undercut the tape bond and interfere
with the normal adhesion forces. Silane coupling agents, added to the IPA/water cleaning solution, can
help reduce the “water-loving” tendency of these surfaces and enhance the tape bond in high moisture
environments.

Copper, brass, and bronze are prone to oxidation even after the VHB tape is applied. To prevent a
weakening of the bond, a lacquer or varnish should be applied to these surfaces. Be sure to test the tape
bond to the sealer on a metal surface to verify good adhesion.

Flexible PVC (vinyl) contains plasticizers that can migrate into the tape and affect adhesion. There are
several VHB Tapes that are formulated to be resistant to plasticizer migration, or 3M™ Scotch-Grip™
Plastic Adhesive 2262, thinned, can serve as a barrier to migration. Rubber materials (e.g. EPDM,
neoprene) can have low surface energy and may also contain plasticizers and oils. These require the use
of an adhesion promoter for stable bond strength. Test for compatibility with flexible PVC and rubber
materials by aging bonded samples for a week at 150°F (66°C) and check for softening of the adhesive,
discoloration or reduction in bond strength.

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