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What is the contact angle?

TWI Frequently asked questions

by Richard Court

The contact angle, θ, is the angle that a droplet of liquid makes at the point which it makes contact with the surface upon which it is resting. The size of the angle provides information relating to the surface energy and therefore the wetting capacity of the surface. This is especially relevant to adhesive bonding and coating processes. The smaller the angle, the higher the surface energy and the easier it will be to wet the surface. For more information, please see FAQs relating to surface energy and wetting.

Further information

FAQ: What is meant by wetting and how can it be used?

FAQ: What is the 'surface energy' of a material, and how can it be determined?

FAQ: What are the typical values of surface energy for materials and adhesives?

FAQ: What treatments exist for altering the surface energy of a material?

For assistance with this technology please contact Adhesives, Composites and Sealants