Q–I recently visited a home center in search of some glue for a project. Once in the correct aisle, I was overwhelmed by the assortment of glues, adhesives, cements and epoxies. Is there a multi-purpose glue that will work for virtually all projects or do I have to buy some of each to successfully glue objects in my home? Are there some really good waterproof glues available for bonding wood together? Do they still use old horses to make glue?
A–I can appreciate your dilemma. There are many glues, adhesives, cements, and epoxies. Most, if not all, of these products are excellent when used correctly. Unfortunately, to the best of my knowledge, there is no one “wonder” glue that will work for all of your jobs. Different jobs and objects will require you to use different glues. However, there is one newer glue that is not only strong but also will successfully bond many, many things together. More on that in just a moment.
The ingredients of glues and adhesives can be simple or complex. Animal glues are still made today. These simple, yet effective, glues are often made from proteins found on the underside of animal hides. Bones, blood, and other animal byproducts such as milk can even be used. Most adhesive experts agree that these glues probably were discovered quite by accident, when early man saw how difficult it was to remove dried blood and skins from spears, knives and other objects.
Most modern glues and adhesives are synthetic. They create a bond either mechanically or chemically. Simple glues, such as the white school glue and yellow carpenter’s glue, bond mechanically to objects. The glue itself actually flows into the pores of the object.
On a microscopic level, this mechanical bond can be very effective. In fact, these inexpensive glues can achieve strengths near 4,000 pounds per square inch when used on high density woods such as hard maple. To achieve the best bond when using white or yellow glues, the objects being glued need to be very uniform, smooth, and dust free. If there are cracks or voids, the bond will be poor.
Excess yellow glue can seal surface pores adjacent to a glued wood joint, creating a nightmare for woodworkers. The sealed, visible wood pores will not accept wood stain.
On your woodworking projects, avoid wiping excess glue from a joint. Let it dry and then sand it off.
To minimize this problem, some manufacturers add small wood fibers to their yellow glues. These wood fibers readily accept the wood stains.
Other glues, including many epoxies, rely on specific adhesion bonding. These adhesives react chemically with the object they stick to. Epoxies are not only very strong but also very selective. Special formulations often are required to suit specific materials.
The newer urethane glues are quite interesting. They are actually activated by moisture. These glues can often be used on lumber that has up to a 25 percent moisture content.
These glues actually foam and expand as they cure. This expansion helps to fill small voids between the objects being glued.
The newer polyurethane glues mechanically bond to masonry, glass, wood, metal and many plastics. Once dry, the urethane glues are highly water resistant. These glues are probably the most versatile ones you will find.
Buy these glues in smaller bottles because they can actually set up within the bottle. As you use the glue, the bottle fills with air. Moisture in the air can react with the remaining glue and cause it to spoil.
Construction adhesives in a tube are formulated to bond poorly fitting materials. They are very water resistant and can easily bridge gaps. However, these glues are generally not as strong as the others. These adhesives are for rough work where clamping is often difficult.
To achieve the best results when using any glue, always read the directions on the label and follow them to the letter. It is always best to test a glues before using it. This will take you an extra day or so, but it will be worth it.
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Have questions about the remodeling process? Write to Tim Carter, c/o The Chicago Tribune, P.O. Box 36352, Cincinnati, Ohio 45236-0352. Questions will be answered only in the column.
For a list of adhesive and urethane glue manufacturers, a table of glue characteristics, and other tips on using glues effectively, send $2 and your name and address to Tim Carter at the above address.
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