Epoxy glue is a two component adhesive with amazingly high bonding strength. Being a copolymer material, it forms cross linked molecular chains when the two parts making it up, resin and hardener, are mixed. Epoxy can be used to hold together many materials, including wood, aluminum, fiberglass, various types of plastic, stone, cement, and steel. After it hardens, it is waterproof, and will withstand heat better than any other adhesive type.
Epoxy glues are typically made in two types, fast setting, which hardens in around ten minutes, and slow setting, which takes up to 30 minutes to harden, and is used for larger applications where assembly takes more time and multiple clamping points are required.
There are also specialized epoxies which cure when exposed to ultraviolet light, like those used by your dentist or in the optoelectronics industry. No matter the setting type, you should only mix as much epoxy as you need to immediately use, since any extra in the batch will be rendered useless after a short time.
How to Mix 2 Part Epoxy Glue
Epoxy adhesive is supplied in two separate containers, resin and hardener, which are mixed before application to create a thermal reaction. The manufacturers recommendation should be followed for the proper ratio of epoxy resins to hardener; it is usually between 5:1 and 1:1.
Correct mixing is one of the most important factors in how successful your epoxy glue bond will be. Improperly mixed epoxy will fail to set up correctly and you can ruin your project, or at the least, you will have to painstakingly remove the failed epoxy residue from the surfaces completely before trying again.
You should never mix resins and hardeners from different types or brands of epoxies, as formulations are carefully matched to create the chemical bond.
Many epoxies come with measuring pumps for use with quart or gallon containers. If there is no measuring pump supplied, then a clean plastic measuring cup or uncoated paper cup can be used. You will also need a clean wooden or plastic mixing stick, and safety equipment (see below).
Mix the two components thoroughly for the recommended length of time. Stir the mixture vigorously, scraping the sides and bottom of the mixing container in the process as well. If you’ve mixed it well, the epoxy should be a whitish, opaque color and will begin to produce heat as the thermal reaction occurs.
Because the mixture of the resin and hardener does produce heat, sometimes enough to melt through it’s container and even combust, you should wait until it hardens before disposing of any leftover mixed epoxy glue. Once it hardens, you can safely put it into the trash.
Your surfaces to be bonded should be cleaned of dust, dirt, grime oils and any residues from sanding prior to mixing the epoxy. To ensure a clean surface, wipe it down with isopropyl alcohol, distilled water, or a citrus-based cleaning solvent. Follow the manufacturer’s instruction for application.
Generally, for joining two surfaces, both surfaces are coated with epoxy, using a disposable glue brush or roller. If the materials are permeable ones, such as wood, wait a minute or two for the adhesive to penetrate the material. Press the two surfaces together. For maximum bond strength, clamp the two pieces together, but do not apply so much pressure that you force the adhesive out from between the two surfaces.
The time needed for epoxy to cure will depend on the room temperature as well as the type of epoxy, and the humidity and how much epoxy is used also are factors. If you find the epoxy is setting too fast, try lowering the room temperature. Another trick to keep the epoxy mixture from hardening in the container is to pour it into a shallow container like a pie tin, since the deeper a container, the sooner the epoxy will tend to set.
Epoxies contain volatile organic compounds and phenols which can be hazardous to your health. These are seriously strong chemicals and should be treated with respect, as anyone who has had epoxy exposure for any length of time can tell you. Always follow the precautions and safety guidelines in the manufacturers instructions.
When working with epoxy glue, you should always disposable gloves and eye protection. All contact directly with skin is to be avoided, as epoxy, especially the hardener component, causes skin irritation and rashes. Breathing of vapors should be avoided, so a respiratory mask should also be worn.
Uncured epoxy on your skin should be cleaned off the skin immediately, using waterless soap. Do not ever clean epoxy from the skin with any kind of solvent. If any epoxy contacts your eyes, flush immediately with running water for 15 minutes; medical attention should be sought if discomfort continues.
Epoxy should only be worked with in areas having good ventilation. When sanding hardened epoxy joints, a dust mask is to be worn. If the epoxy has cured for less than a week, use a respirator.
Epoxy resin, hardener or mixture accidental spills should be cleaned up using a squeegee and paper towels. You can use sand or cat litter to soak up larger spills. Isopropyl alcohol or white vinegar can be used to clean any residue up. Don’t forget to wear protective gloves when cleaning up spills.
Do not dispose of resin or hardeners in liquid states; prior to disposing containers, puncture the corners of can and drain residue into clean containers for re-use. Follow relevant local and federal regulations for safe disposal.
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