How to Properly Prepare Surfaces for Epoxy Adhesives
Any good two-part epoxy adhesive can bond virtually any two surfaces that are properly prepared. If you properly mix and apply the adhesive but it does not hold, odds are you either did not use the correct type of epoxy or did not properly prepare one or both surfaces to enable the strongest potential bond.
Epoxy can bond a variety of products with a very strong and lasting hold when you use the right adhesive with the correct and properly prepared materials. Some of the most commonly epoxy-bonded materials include:
- Metal, which requires significant preparation.
- Plastic, which might need cleaning and sanding.
- Wood, which often has a porous surface subject to contamination.
- Glass, which often needs a clear and fast-drying epoxy.
- Concrete, which requires a very high-strength epoxy.
No matter which type of material you intend to bond with epoxy, choosing the correct two part epoxy and ensuring the surfaces to be bonded are properly prepared will deliver the best results. That is why a great all-purpose epoxy like Infinity Bond non-sag epoxy can handle a wide range of bonding duties. The following tips also should help you to learn how to properly prepare surfaces for epoxy adhesives.
Wash Away All Contaminants
A clean surface is ideal for ensuring a solid bond and the best results with commonly used two part epoxy adhesives. No matter what type of material or surface you are bonding, you need to ensure it is clean of any contamination that could negatively affect the epoxy adhesive bond.
Anything containing grease, oil, wax or similar substances is especially problematic and must be removed with a thorough cleaning. You can use a variety of solvents and other compounds that remove all traces of oil, grease, wax and other compounds that form effective layers between the surfaces that you intend to bond and the epoxy adhesive.
A plain white paper towel is a great way to check for potential contaminants on the surface you are preparing to bond. Just take a clean piece of paper towel and rub it across the area upon which you are working. If the towel comes away clean, the surface is fine. If it picks up oils or other contaminants, you need to give the area a thorough cleaning to ensure you can get the best possible bond.
Make Metal Surfaces Shine
No matter what kinds of metals you might intend to join together with a two part epoxy adhesive, you need to make it shine to know the surface is clean. Steel, aluminum, copper, lead and virtually all other kinds of metal all produce a relatively bright shine when perfectly clean. A piece of 80-grit sandpaper or similar substance is perfect for sanding down the corroded surfaces of metal objects and exposing the good, clean metal that you want to bond.
A bit of preparation with acetone, mineral spirits or even rubbing alcohol can help to ensure there are no oils, grease, wax or other substances collecting on one or more pieces of metal. If you are unsure, you can use the paper towel test to find out. Once you are certain the surface is perfectly clean, you can sand it down to open up the more porous areas and enable the epoxy to provide the best bond.
Another option for bonding metals is Methacrylate (MMA) adhesives. These are two-part adhesives, similar to epoxy, but provide exceptional bonds to metals with little or no surface preparation.
Preparing Woods and Plastics
Wood has a naturally porous surface, and plastic is easy to open up with some mild sanding of the surface. Wood typically comes clean with some sanding, so if there are any contaminants on the surface, some light sanding usually will remove it.
Plastic can be trickier due to its tendency to reflect light and look shiny when oil of something similar might contaminate it. If you are unsure whether or not plastic is ready for bonding, you can apply a small amount of water with a squirt bottle and look for any beading. If the surface is contaminated, the water will bead up and run off. A porous plastic surface will allow water to sink in a bit, just like epoxy.
Preparing Glass, Ceramics and Other Materials
A good two part epoxy can bond glass, ceramic and other items that many adhesives cannot penetrate to provide the kind of bond needed. Glass and ceramic items can be difficult to bond due to the nonporous nature of their respective surfaces, which also might have a layer of oil or another substance that makes bonding virtually impossible. You can clean the surfaces and prep them with sandpaper to provide the strongest possible bond with the correct type of epoxy.
Need Advice on Epoxy for Your Application?
It can be difficult to choose an epoxy with the right combination of properties. That’s something we can help with. Contact one of our Application Specialists for advice on which epoxy is right for your application.