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CHOOSING THE RIGHT GLUE CAN BE A STICKY MATTER
By Diane Newman of Beacon Adhesives
Having the right tool for any project is very important for its successful completion. Glue is a key tool used for creating many different types of craft projects. Using the wrong glue can result in a project that won’t stick together at all, falls apart later, or ruins the materials, causing frustration as well as wasting time and money.
However there are endless choices which can be very confusing. Should you use a white or tacky glue, water or solvent based, instant glue or glue gun, rubber cement or paste? Add to those choices acrylics and pressure-sensitive adhesives.
One of the first things to consider when choosing a glue is the types of surfaces that are being bonded together. Basically, there are three different types of surfaces to consider when selecting a glue.
Non-porous – This type of surface is generally slick and shiny and does not absorb moisture. Glass, metal, acrylic, plastic, varnished wood, polymer clay, and glossy paper are examples of non-porous surfaces.
Semi-porous – Certain treated woods, coated papers and fabrics, and fun foam are examples of semi-porous surfaces that do not absorb moisture evenly or quickly.
Porous – Most papers, fabrics, untreated woods, plaster, and some clays absorb moisture fast and evenly, making it relatively easy for glue to adhere.
TYPES OF GLUE
Glues have been used for thousands of years and originally were made from natural materials such as plant starches and fibers; from the hide, horns and bones of animals, and even from egg white and cheese! Over the centuries, glues have become much more high-tech and sophisticated and now are made from many synthetic as well as traditional materials.
Here is a list with a brief description of each of the more common glues available.
Mucilage is made from potato starch, gum Arabic or fish scales. It still is used mostly on paper and gives a weak, quick-drying bond that can become brittle and discolored over time. It is also sensitive to moisture and temperature. The bond it creates is not long-lasting.
Paste is what you use in school. It is made from plant starches or fibers ( corn, rice, and wheat) or from methyl cellulose. Paste has a high water content and is not very stable in temperature extremes. It can be used on most papers and for making papier mache and as a binder. It should only be applied to paper that can tolerate a high water content.
Rubber cement is made from latex harvested from the rubber tree. It is a medium strength glue that is solvent-based, highly flammable and very flexible. It will not wrinkle paper and is easy to remove. It cannot be used to bond wood or other structural materials.
White glue is a quite versatile and used extensively in arts and crafts. It was developed in the 1940s and is also known as polyvinyl acetate (PVA). White glue forms a medium bond and cannot hold heavy objects or anything intended for outdoor use. White glues vary in flexibility, but most have a high water content, dry clear and can be removed with water while still wet.
Clear glues include glue sticks, photo, and envelope glues and basting glues. They are water-based, non-toxic synthetics designed for porous surfaces. They do not discolor or become brittle during time, maintain good flexibility and are not as susceptible to humidity although they generally are water-reversible. If applied in a thin coat, they will not wrinkle or show through paper and frequently are used for bonding vellum and glossy photo papers.
Tacky glues are thicker, stronger, and stickier than white glues. They dry clear and are suitable to use on porous, semi-porous, and non-porous surfaces. They are not particularly good for outdoor use since sunlight, heat, and cold will weaken them. It is important to test tacky glues on paper before using them on a project because these glues vary in strength and viscosity. Tacky glues are used extensively in craft applications because of their versatility.
Acrylic-based glues contain acrylic polymers and remain flexible. They are not affected by heat or humidity. Many are resistant to ultraviolet rays, dry clear, and maintain an extended open time so that surfaces can be repositioned if necessary. They are water-resistant but not waterproof for outdoor use. Some acrylics may soak or show through papers, especially vellum and tissue.
Pressure-sensitive adhesives (PSA) offer many different types to choose from including tapes, film, dots, die-cuts, mounting corners, and stickers. They also are used in laminating machines. PSAs can be used for many applications with a wide variety of materials. PSAs often are acid-free, Ph neutral, and suitable for use with photos, albums, scrapbooks, and other memory crafts.
Glue guns work by melting a glue stick in an insulated heating element until the glue flows freely from the nozzle. Glue guns are available with many different temperature settings and can be either plug-in or cordless. Glue sticks are composed of polymer and resin and are non-toxic. Selecting the right temperature glue gun is very important because high temperatures can damage certain materials. Always use caution when handling glue guns to prevent burns. They should never be used by children.
Solvent-based glues usually are much stronger and more permanent than other adhesives. They set and dry quickly. Most of these powerful glues are flexible and many are waterproof. Solvent-based adhesives are difficult to remove once dried although dry cleaning sometimes will remove glue from clothing. They work well on hard-to-bond surfaces such as glass, metal, vinyl, plexiglass, etc. and often are used for filling gaps because of their strength and flexibility. Most are flammable, contain toxic substance, and should be kept away from children.
Instant glues, also know as cyanoacrylates, are super-fast bonding but have a very short open time. They are applied drop by drop on dry surfaces and have a very limited shelf life once opened. They must be used with caution because they are almost impossible to remove and even can bond to skin. Instant glues are quite strong but are not suitable for use on some plastics, foam, and fabrics. Avoid using where the glue will be exposed to moisture. They also have a tendency to lose strength over time.
Epoxies provide the strongest bond of any adhesive type. They are usually composed of two parts-a resin and an activator or hardener that must be mixed together in the correct ratio before applying. After curing epoxies can withstand even the heat of a dishwasher. They also can be painted, sanded, and drilled. Many are clear and colorless but have a tendency to yellow over a long time period.
TIPS FOR APPLYING GLUE
1. ALWAYS carefully read the manufacturers directions.
2. Test first. Use scrap materials to see if the glue will work well on the surface you will be bonding.
3. Work in a well-ventilated area, particularly when working with solvent-based or flammable glues.
4. Protect your skin when working with super-strong or solvent-based glues to prevent allergic reactions or gluing skin together. Rubber gloves work well.
5. Cover your work surface. Some glues can remove veneer and stains from furniture. Good work surface protectors are wax paper, coated freezer wrap, aluminum foil, plain paper (newsprint may smear), a plastic tablecloth or use an old shower curtain for a drop sheet.
6. Be sure the surface is clean, dry, and free of dust and oil before applying glue.
7. Use an appropriate applicator depending on either the type of adhesive being used or the surface properties. Tip pens, brushes, plastic spatulas, craft sticks, syringes, Yorker bottle tops, wood skewers, tweezers, toothpicks, and rubber brayers can be used.
8. Less is more for most glue applications. If too much glues is used, it will ooze when any pressure is applied, take much longer to dry, and actually not hold as well since it will over-saturate the surface and be unable to penetrate.
9. You may need to use more than one type of glue on a project if you are attempting to bond extremely different surfaces together. Many professional craft designers often will use two or three different glues then constructing a project.
10. Most glues have a limited shelf life—the period of time in which they will remain strong. If you use a glue that’s too old or has gotten thick or discolored your project may fall apart quickly.
11. Clean up while the glue is still wet. Keep paper towels or baby wipes on hand. Clean applicators before storing.
12. Allow glue enough time to dry. There is a difference between a glue’s “grab” and its dry time. Basically, grab is how well glue holds onto the surface right away, while dry time actually is how long it takes to bond the surfaces together permanently. Even though a glue may grab quickly, it may need many more hours to dry thoroughly. Slick surfaces are harder to hold and thy may need extra dry time. Washable glues should be given a t least a week to dry before washing.
13. Store glue out of temperature extremes and away from direct sunlight. Be sure glue is covered properly to prevent evaporation and discoloration.
Try these books to learn more about adhesives and how to use them:
The Complete Guide to Glues & Adhesives by Nancy Ward & Tammy Young and The Crafter’s Guide to Glue by Tammy Young. They also contain excellent tips and great projects. Information from the books is included in this article.