Wednesday, September 15, 2010

Tips & Tricks #12: Stick to it! (Part 2a) - Expoxy Moxie A.K.A Getting the Most of Out of Your Glue!

Sometimes you need to stick some things together and a piece of tape just won’t do the job. Let’s face it, tape is convenient and quick, but it’s never going to be a really permanent solution and most of the time it looks really tacky (pun intended). When you’re ready to get serious about adhesives, there’s only one place to turn – glue! To put it in very basic terms, glue is a liquid, or semi-liquid, substance with adhesive properties (meaning it’s sticky), that dries to a hard, non-adhesive film, allowing two surfaces to be stuck together while the glue is wet, with the bond becoming permanent when it dries. The variety of glues available in our modern, industrial society is mind-boggling, not to mention all the different brand names and sub-varieties that are out there, so we’ll confine our discussion to a few of the ones you’ll most likely encounter as an artist.

Natural Glues
Fortunately for all the horses, cows, pigs and other hoofed animals, Hoof Glue, which was one of the most widely used glues all over the world for thousands of years, has largely fallen out of favor except for a few specialty applications in cabinetry and furniture-making. Thankfully you are unlikely to encounter it, or any of the other types of glue made from animal products, in Binders or any other art store and tales of the retired race-horse being shipped off to the glue factory are far less common than they used to be! However, some plant-based glues are still in use every day and may often find their way into art projects for specific reasons.

Among the most commonly used plant glues is Rubber Cement, which is made from latex, a naturally occurring, sap-like fluid that is obtained from many plant species, combined with a solvent to keep it in liquid form until it evaporates. Rubber Cement remains popular because it is so easy and safe to use that even children can enjoy it, plus it tends to be easily removable without damaging the surfaces that it was adhered to, so it can be very useful in experimental projects where the artist needs to be able to make changes easily. Rubber Cement is not recommended for long-term permanence, however, since the bond is relatively weak and things are likely to fall apart at some point.

The other type of plant glue that you might come across is Methyl Cellulose, which is created from the basic chemical building blocks of plant fibers. Methyl Cellulose typically comes as a white powder which, when mixed with the right proportion of water, forms a not-very-strong adhesive that works best on porous surfaces like paper. The great advantage of Methyl Cellulose is its archival qualities, which makes it very desirable for bookbinders and artists working with very delicate materials like Japanese papers.

Polyvinyl Acetate (PVA Glue)
We’re all familiar with the glues made from rubbery synthetic polymers, whether we know it or not! They name sounds fancy, but PVA is actually the main ingredient in some of the most commonly used glues today. In particular, Elmer’s Glue, an all-purpose glue for arts and crafts projects, and Carpenter’s Glue, for gluing pieces of wood together, are a staple in our lives. Elmer’s Glue, much like Rubber Cement, is very easy to use and the variety known as School Glue is safe and simple enough for young children to use. The results are more permanent though, so don’t expect to be pulling things apart without ruining them!

Elmer’s Glue will bond to just about anything, but is stronger with porous surfaces. Carpenter’s Glue is a stronger, slower drying version of Elmer’s Glue that claims to create a bond stronger than the wood itself! The slow drying time of the glue allows the adhesive to penetrate the fibers of the wood, creating a very permanent solution that is not easily broken. PVA Glue is also non-acidic in nature, so the more chemically pure versions of it, such as the ones made by Lineco or Gamblin, are suitable for archival applications and can make a more durable alternative to Methyl Cellulose. Mod Podge is another PVA brand that is better quality than the Elmer’s, but at a lower price point than the truly archival ones. All PVA Glues require some degree of porosity to the surfaces that are being glued together, so they work best on paper, wood, cloth, etc.

Thermoplastic Glue
The Glue Gun! Most of us are familiar with it and have probably used a Glue Gun at least once. The idea is simple, when thermoplastic is heated it turns to a semi-liquid form with adhesive qualities which maintain a bond once the glue cools down and dries. The glue is neither strong, nor archival, but it is very easy to use (just don’t burn yourself!) and it sticks to just about anything! If you want to add pieces of metal, plastic or ceramic into your creations, a glue gun is the simple way to go!

Polyurethane Adhesive
In its bright orange display, the Gorilla Glue is hard to miss on BINDERS’ adhesive aisle! Gorilla Glue is another type of synthetic polymer glue, but utilizing polyurethane rather than polyvinyl. This stuff is really strong and, although is works best on smooth, non-porous surfaces, it will stick to just about anything! Gorilla Glue is vastly more permanent than thermoplastic, but requires more skill and patience to use.

Like Carpenter’s glue, Gorilla Glue requires as long as 24 hours to dry and the use of clamps is recommended to ensure a tight bond is achieved. The other, more tricky fact is that the glue expands as it dries, often resulting in the glue bubbling out from between the two surfaces. Gorilla Glue comes in a transparent variety, which is more visually appealing, but it can still ruin the appearance of the final product if not handled correctly. Experience is the only way to get a handle on it – try doing tests on scraps to get a feel for how much to put on before you add it to your artwork! Unless you are doing heavy sculpture work, this is the toughest glue you will be likely to need.

Stay tuned for part 2B of Epoxy Moxie, in which we’ll take a look at Spray Adhesives, Glue Sticks and, of course, Epoxy!

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