Preparing a surface for adhesive bonding is one of the most important things you can do to obtain a sturdy and strong bond. The adhesive needs to cover large areas of the two surfaces you are bonding together, and the task becomes easier when the two surfaces are clean and smooth. Continue reading to find out how to properly prepare your surfaces for adhesive bonding.
Pretreating the substrate surface before using the adhesive will assist in ensuring you get the most efficient and effective bond possible.
There are three methods of pretreatment: physical, mechanical or chemical:
- Physical methods require special The substrate surface is cleaned and then exposed to high-energy charges such as flame, plasma or corona discharge.
- Mechanical treatments include sandpaper, brushes or some other type of scraper to remove any contaminants like paint or rust. After sanding or abrading the surface clean, a solvent is used to remove the dust or leftover chemicals.
- Chemical pretreatments, like acid etching or dipping the substrate into some other type of chemical to clean the surface, are an effective method also.
You need to prepare the surface of the substrates to achieve optimal bonding. Preparation may require using a detergent or solvent to clean the materials as thoroughly as possible and remove the dust, grease, and oil.
Once it is clean, consider using a bonding primer. This will give you a faster set time for just the right type of bond.
Primers, also known as adhesion promoters, modify the surface energy. This will ensure a chemical reaction occurs between the adhesive and the surface, and it can also protect the surface from contamination after the post-treatment process. Primers come in many types and are designed for the type of adhesive it will come into contact with, such as this primer for water-based adhesives. Therefore, you must ensure the primer you are using fits the adhesive you want to use.
In addition to bonding primers, you can also use an accelerator to help promote adhesion. There are several types available. Some specifically designed for certain types of surfaces or glues, and others, like the Vibra Tite 623 General Purpose Accelerator, are manufactured to work on various brands and types of glue.
Types of Surfaces
Three of the most common substrates that are often bonded together using adhesives are metal, wood and plastic. Each surface has its own properties and should be prepped differently before applying adhesives.
Metals, in addition to a reputation for strength and durability, are often tough to work with and can be difficult to cut and mold into the desired shape. Usually, chemical cleaning using solvents or other methods work better for metal surface preparation than detergents or soaps.
Wood surfaces in woodworking shops and manufacturing facilities, where wood is one of the primary substrates, are often contaminated with bits of resin and wax. To prepare wood surfaces for adhesives, pretreatment is strongly recommended. You also need to dry the wood first prior to pretreatment.
Dust, dirt, oil and grease can easily contaminate plastic. These contaminants can also migrate around the surface due to the nature of the plastic material. To prepare plastic surfaces for adhesives, liquid solvents should be used along with abrasion and chemical surface modification.
Use a Super Glue primer like the Vibra Tite 625, made specifically to use with plastic substrate, to help accelerate the process.
Detergent and Solvents
The efficacy of a detergent or solvent depends on the substrate and the sorts of contaminants you want to remove.
Detergent works reasonably well on most types of dirt and oil. Some soaps or other detergent-based cleaning products may react with metals causing an unfavorable chemical reaction that can weaken the bond or the metal. If you use detergents, rinse the metal thoroughly and dry it well.
Certain solvents are better than others at removing specific classes of contaminants. For example, if you have a lot of wax, resins or lubricant buildups, use a hydrocarbon solvent. For cutting or protective oils, ketones are an excellent choice. Alcohols remove fingerprints very well.
You should always wipe your substrates with solvent prior to pretreating the surfaces. If you don’t, abrading the surface will only push some of the oil or grease into the wood or plastic, making the substrate more difficult to clean and resistant to the adhesive.
Always Be Prepared
Preparing your surface for adhesive bonding is an important part of ensuring a secure and strong bond. These surface treatment processes should be tailored to the surface you are working with as well as the adhesive you are using.