In our work, making stuff usually means cutting large things into successively smaller things, and then attaching those small parts to each other to create something completely new. The process can involve welding, mechanical fasteners and--especially--glue. Whether it's a rig for a MythBusters TV episode, a special-effects model for a film or a home project, glue is usually the soul of the build.
THE FUNDAMENTALS OF STICKUM SELECTION
ADAM: The first consideration is to match the glue to the properties of the materials you intend to join. Otherwise, you'll end up like my friends who try to repair their sneakers with wood glue. It never works: The properties of wood glue (stiff) don't match the properties of sneakers (flexible). Another consideration: the coefficient of expansion. All materials expand and contract at different rates in response to their environment. For our purposes, a glue's usefulness is based largely on how much its coefficient of expansion matches or exceeds that of the material it's bonded to.
JAMIE: The chemical reaction used to set glue is another point of differentiation in adhesives. One type used in optics and dentistry sets with ultraviolet light. A new version of this glue allows light to set one part of the glue, which then starts a reaction that permeates the join, so that places the light doesn't reach are catalyzed. The advantage is that you have plenty of time to position the materials; when you're all set, you aim the light and--bang!--you're done. A fan of our MythBusters show once sent me pre-impregnated fiberglass that uses UV light to cure. He said he wanted me to cover Adam in it and make him run outside to see how far he got before he froze up in the sun.
QUICKER KICKER
ADAM: My favorite glues are cyanoacrylates with accelerators (super glues-let's just call them CAs). I build 90 percent of my projects with this family of adhesives. They're fast and they come in different viscosities. With an accelerator, they set in under 10 seconds. (I'm not kidding.) In our workshop we usually call it Zip Kicker, which is the name of our favorite brand. But be forewarned: CA accelerators have a smell that puts some people off. If you've got CA glue that you want to set in a few seconds but don't want to have your nostrils reamed, here's a cheap off-the-shelf trick: baking soda. After you lay in a little CA, sprinkle on baking soda-and voila! It kicks instantly. And there's no smell. (There is, however, a rapid exothermic reaction--that is, it gets hot--so use caution.) Baking soda also adds mass to the glue, which means I can use it and the CA as a structural medium for strengthening joints.
JAMIE: Once, when we were on a MythBusters shoot, Adam broke his black horn-rims at the bridge. Even a CA is not real strong on small surfaces, so I made a sort of fiberglass. I took a piece of cotton cloth, wrapped it around the joint, and let the glue soak in and kick. I colored the cloth with a black Sharpie, and Adam was back at work in 5 minutes.
You can also use a CA as a varnish. Not only that, but you can take a softwood, like redwood, and make it feel like a polished hardwood. You can buy it in a larger quantity at a hobby shop--you can get 2 ounces or larger there--and squeegee it onto the surface with one of those credit cards that companies are always giving away. Try it first with a medium-viscosity glue. The porosity of the wood usually kicks the glue within a few minutes, although if you use the spray kicker very lightly and evenly, you can lock the glue right away.
One weird thing: The glue sets so quickly that you don't get "grain raise," which occurs when a varnish soaks into the wood and dries. The woodgrain swells somewhat unevenly, and you end up repeatedly sanding and revarnishing. Very tedious. Not so with a CA. Let it soak in and kick, then sand the surface and you instantly have something that is as smooth as glass and feels like the kind of old wood that is velvety smooth from having so many hands touching it for a long time. Note: CA is expensive compared to regular finishes. When you use CA, you trade cost for speed. I wouldn't finish my floors with it, but on small projects it's a reasonable thing to do and a little goes a long way.
In our work, making stuff usually means cutting large things into successively smaller things, and then attaching those small parts to each other to create something completely new. The process can involve welding, mechanical fasteners and--especially--glue. Whether it's a rig for a MythBusters TV episode, a special-effects model for a film or a home project, glue is usually the soul of the build.
THE FUNDAMENTALS OF STICKUM SELECTION
ADAM: The first consideration is to match the glue to the properties of the materials you intend to join. Otherwise, you'll end up like my friends who try to repair their sneakers with wood glue. It never works: The properties of wood glue (stiff) don't match the properties of sneakers (flexible). Another consideration: the coefficient of expansion. All materials expand and contract at different rates in response to their environment. For our purposes, a glue's usefulness is based largely on how much its coefficient of expansion matches or exceeds that of the material it's bonded to.
JAMIE: The chemical reaction used to set glue is another point of differentiation in adhesives. One type used in optics and dentistry sets with ultraviolet light. A new version of this glue allows light to set one part of the glue, which then starts a reaction that permeates the join, so that places the light doesn't reach are catalyzed. The advantage is that you have plenty of time to position the materials; when you're all set, you aim the light and--bang!--you're done. A fan of our MythBusters show once sent me pre-impregnated fiberglass that uses UV light to cure. He said he wanted me to cover Adam in it and make him run outside to see how far he got before he froze up in the sun.
QUICKER KICKER
ADAM: My favorite glues are cyanoacrylates with accelerators (super glues-let's just call them CAs). I build 90 percent of my projects with this family of adhesives. They're fast and they come in different viscosities. With an accelerator, they set in under 10 seconds. (I'm not kidding.) In our workshop we usually call it Zip Kicker, which is the name of our favorite brand. But be forewarned: CA accelerators have a smell that puts some people off. If you've got CA glue that you want to set in a few seconds but don't want to have your nostrils reamed, here's a cheap off-the-shelf trick: baking soda. After you lay in a little CA, sprinkle on baking soda-and voila! It kicks instantly. And there's no smell. (There is, however, a rapid exothermic reaction--that is, it gets hot--so use caution.) Baking soda also adds mass to the glue, which means I can use it and the CA as a structural medium for strengthening joints.
JAMIE: Once, when we were on a MythBusters shoot, Adam broke his black horn-rims at the bridge. Even a CA is not real strong on small surfaces, so I made a sort of fiberglass. I took a piece of cotton cloth, wrapped it around the joint, and let the glue soak in and kick. I colored the cloth with a black Sharpie, and Adam was back at work in 5 minutes.
You can also use a CA as a varnish. Not only that, but you can take a softwood, like redwood, and make it feel like a polished hardwood. You can buy it in a larger quantity at a hobby shop--you can get 2 ounces or larger there--and squeegee it onto the surface with one of those credit cards that companies are always giving away. Try it first with a medium-viscosity glue. The porosity of the wood usually kicks the glue within a few minutes, although if you use the spray kicker very lightly and evenly, you can lock the glue right away.
One weird thing: The glue sets so quickly that you don't get "grain raise," which occurs when a varnish soaks into the wood and dries. The woodgrain swells somewhat unevenly, and you end up repeatedly sanding and revarnishing. Very tedious. Not so with a CA. Let it soak in and kick, then sand the surface and you instantly have something that is as smooth as glass and feels like the kind of old wood that is velvety smooth from having so many hands touching it for a long time. Note: CA is expensive compared to regular finishes. When you use CA, you trade cost for speed. I wouldn't finish my floors with it, but on small projects it's a reasonable thing to do and a little goes a long way.
BREAKOUT CEMENT
JAMIE: For any truly difficult gluing job-metal to glass, fur to ceramic, foam rubber to metal-we rely on contact cement.
ADAM: My favorite brand is Barge glue; it's particularly tenacious. In the MythBusters episode "Escape From Alcatraz," we tried to verify whether three prisoners could have actually made a successful jail break from the Rock in 1962 in a raft made of stolen raincoats. We took large squares of latex material from 24 raincoats and assembled them into a 13 1/2-ft. triangular pontoon raft with a floor. Each seam got a coat of Barge glue, which we cured with a blow-dryer and then pounded together with a mallet for strength. The raft held air long enough for the 51-minute, 3-mile journey from Alcatraz to the Golden Gate Bridge, but the prisoners' fate remains unknown.
