Preparing your substrate for the best bond possible is crucial when applying a PSA because it helps to ensure the success of the bond. There are different processes to prepare a substrate for an application.
The process is dependent on:
- Adhesive type
- Substrate conditions
It’s important not to overlook the surface energy of the substrate. To create a higher surface energy, it’s important that the surface is clean, dry and rough.
- Clean: Start by cleaning the surface of any debris and contaminants. The standard way to prep the surface is to use a 50:50 mixture of isopropyl alcohol (IPA) and water. To remove heavier oils, use a degreaser or solvent-based cleaner.
- Dry: Working with a dry service is important because it helps to ensure a secure bond. Having moisture on the substrate will promote a poor bond.
- Abraded: Roughing up the surface with sand paper can create more surface energy and provide a slight grip for the adhesive to attach to. PSA can flow into a rough surface to maximize bond strength based on higher contact area.
If the substrate still has a low surface energy after following these steps, a primer may help. When picking a primer consult your supplier to find what primer would work the best. If a primer isn’t an option, a flame treatment, surface roughening or chemical etching could be alternatives that might work.
Bond Strength can be measured by a test method called the Peel Test (Pressure Sensitive Tape Council or ASTM)
- Peel Values indicate the bond strength of the PSA to a particular substrate
- Initial adhesion indicates how well a PSA has bonded to a substrate after a short period of time, usually seconds or minutes
- Ultimate adhesion refers to a PSA’s bond strength after 72 hours