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Good pre-treatment in 3 steps

Good adhesion is an important condition for a durable bond. On some substrates, good adhesion with adhesive or a sealant is not possible right away. In this blog, we give you some practical tips for pre-treatment.

How do you pre-treat a substrate?

A good, strong bond depends largely on the use of the right products. Naturally, proper application is a requirement for this. But what is the right pre-treatment method? Which products is it best to use for this? And how do you apply them well?
 
Obviously, the answers primarily have to do with the materials you want to bond together. Is this glass, for instance, plastic, fiber-reinforced plastic, coatings or metal? And have these materials already been treated, for example with a graffiti-resistant or scratch-resistant coating?
 
Sealing or bonding is often one of the last steps in the design process, but it is important to think about this at a much earlier stage: when choosing the materials that must be bonded together. Starting work well prepared can avoid many problems.

In this blog, we give you some practical tips for pre-treatment.

"Good pre-treatment is half the work. If you do this properly right away, you will benefit from an optimal bonding or sealing result. But what is the best way to pre-treat substrates? We are happy to give you some practical tips. Make the most of them!" Peter Wieskamp Application Specialist & European Adhesive Specialist (EAS)
Peter Wieskamp
A full pre-treatment consists of three steps:

Step 1: Etching, flame treatment, corona or plasma treatment


If you are using a material that is not easy to bond or seal well, such as a polyethylene (PE), you can etch or flame-treat the substrate, or apply a corona or plasma treatment. This modifies the substrate and makes it more receptive to adhesive and sealant, so that a better bond is created.
 

Step 2: Cleaning and, if necessary, roughening

Make sure the substrate is cleaned well; the substrate of parts to be bonded must be clean, smooth, dry, homogeneous and free of dust, rust and grease. So it must no longer have any ‘extra layer’ of grease or other solids or liquids.

You can clean it with a cleaner or remove contaminants mechanically by sanding or blasting in combination with cleaning. Remember to use your personal protective equipment (PPE) here. If necessary, you can also roughen the surface a little more for an even better result, before cleaning it again.

Is the substrate contaminated or does it need degreasing? For a substrate of glass, metal, plastic or polyester, use fluff-free paper for this with the right cleaner, which you rub several times in one direction. Do not rub back and forth; you will only spread the dirt back over the substrate again. Avoid touching the (clean) surfaces you want to bond, or wear powder-free gloves. Let the substrate dry before you continue with the next step (the open time and drying time depend on the cleaner that you use).

If you wish, SABA can advise you on making the right choice or subject your materials to a laboratory test. We use different test methods, such as the standardized climate test (accelerated aging test) and cataplasm testing (a test with different cycles with large temperature differences and a humid environment, also compliant with DVS 1618).
 

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Step 3: Applying primer or activator

If you do not expect an optimal bond, use a primer or activator, depending on the substrate. Ask our application specialists which products are best to use or see our pre-treatment configurator. Again, remember your PPE. The PPE you need is shown in the safety data sheet.

Take account of the open time (the time within which a product can be applied). It is advisable to pour the amount that you need into a small pot and close the can again immediately. On the can, write the date on which you first opened it. The next time it is needed, you can then check whether the product is still usable. Never use a brush to remove product from the can; this may contaminate the product and can lead to poorer quality. This also reduces its shelf life. Also take account of the minimum drying time before moving on to the next step. The drying time is shown in the product data sheet.

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