Chapter 2: The Cleaning – The Secret to Perfect Double-Sided Tape Adhesion
Last week we talked about the different substrates and how important it is to know them in order to define the most suitable adhesive. At this point, we should be sure that our double-sided tape works, right? WRONG. Knowing the surface to be bonded does not necessarily mean that everything will be fine. First of all, you will have to deal with many other adhesion antagonists—dirt being the main one.
1) Dusty Residues: A Simple Yet Insidious Obstacle
Dust is one of the simplest obstacles to overcome, but it is also one of the most insidious. If we are going to apply an adhesive, we must be sure that our substrate is free from dusty residues. Pay attention! We are not just talking about dust that accidentally deposits on a piece left too long in the office or warehouse.
For example, many industrial components are already “dirty” immediately after production. Compact rubbers or injection-molded plastics are often covered with talc to facilitate their removal from molds. Talc has a strong anti-adhesive power; therefore, for us, it is absolute evil.
How to Remove Dusty Residues
The solution is cleaning with a microfiber cloth. Is it okay to use a tissue? No. Is it okay to use a rag? No. Is it okay to use cotton wool? Absolutely not. This is because our purpose is to clean effectively. If the surface is full of fibers and fluff that were not there before, we have failed.
Moreover, don’t think of a smooth surface. Think of a slightly embossed or rough substrate, perhaps even a little opaque. Even if you just cleaned it from the most evident dirt, it may still be contaminated with smaller fragments.
If you clean the substrate with a cotton pad or a tissue, you are spreading millions of tiny fibers that will stick to your adhesive. If they stick to the adhesive, nothing else can be attached. The microfiber cloth is designed to capture the smallest dirt particles and remove them without contaminating the surface.
When a Cloth Is Not Enough: Using Isopropyl Alcohol (IPA)
You will not be pleased to hear that, especially when the surface is rough or not shiny, wiping with a microfiber cloth is often not enough. This is because dust tends to creep into the smallest cavities of the substrate. Is there a solution? Of course: Isopropyl Alcohol (IPA).
Is it okay to use nail polish remover? No. Is it okay to use ethyl alcohol? No. Is it okay to use universal degreasers? No. IPA is a “softer” industrial solvent with a high cleaning and degreasing power, capable of removing impurities without leaving oily residues.
If you don’t know how to clean a surface properly, ask your adhesive technician—they know best.
2) Grease, Oil, and Adhesive: A Sticky Problem
The title of this paragraph, besides being a homage to Sergio Leone, reminds us that even brand new pieces arriving from the factory may not be clean. Many surfaces are covered with oily substances, lubricants, release agents, or grease. Moreover, objects from previous bonding failures often have sticky residues that are hard to remove.
How to Remove Grease
Fortunately, many products are available, ranging from mild detergents to strong degreasers capable of dissolving the oldest, most stubborn grease. However, many of these products are oil-based and clean by affinity—that is, grease removes grease chemically and mechanically.
Removing Oily Residues
Once the most evident grease, glue, and oil are removed, it is essential to eliminate the oily detergent used in cleaning. Even if the piece looks perfectly clean, it may still have a thin oily film that can interfere with adhesion.
Why? Because oils can infiltrate the microscopic level of the substrate and emerge at an inconvenient time. The solution is, again, isopropyl alcohol and a microfiber cloth.
3) Oxide: The Hidden Enemy on Metal Surfaces
If the substrate is raw metal, check for oxidation. Oxide reduces the surface energy of the metal, significantly hindering adhesion. Be careful! Just because the metal isn’t covered with visible red or green rust doesn’t mean it isn’t oxidized.
How to Recognize and Remove Oxide
All metals in the early oxidation stages don’t show obvious signs until cleaned. Sometimes, wiping with a cloth turns it black—that black residue is oxide.
For delicate or treated metals, use specific products combining chemical cleaning and gentle abrasion. For raw metals, the simplest method is mechanical abrasion with abrasive papers or discs of gradually finer grain.
Cleaning After Abrasion
Never forget to clean the surface thoroughly after abrasion to remove dusty residues, or you risk compromising adhesion. Refer to the section about dust removal for advice.
Final Advice
If you don’t know where to start, ask your trusted technician. They will help you choose the right products and guide you on when and how to use them.
Now that your surface is perfectly clean, can you apply the adhesive? Maybe yes… or maybe no. Stay tuned for the next chapter of Bonding Failures: The Adhesion Promoter.
For more detailed information on surface cleaning techniques, visit 3M’s Adhesive Technical Guide.
Download the attached PDF file.
BMP Team