Remember when all glues were practically the same and it didn't seem to matter which you used? Remember also how poorly most of those glues held and how difficult they often were to apply?
Times have changed. Nowadays, store shelves overflow with a variety of sticky stuff, making choices difficult. But the good news is that modern glues adhere better and generally are easier to apply than their predecessors.
Here is a guide to choosing the right glues and some hints on applying them:
For general household repairs and craft work involving china, glass, porcelain, wood, metal and plastic, white all-purpose glue remains a good choice. Technically, this type of glue is called polyvinyl acetate, or PVA glue.
Apply it by squeezing it from the container directly onto the work, or spread it with your finger or a brush. Pieces must fit closely together without gaps. Clamp them together while the glue sets. Setting takes one to eight hours, complete curing usually takes about 24 hours. Clean away excess glue with water before setting begins. PVA glue dries clear.
For repairs to wood, especially furniture, use aliphatic resin glue, better known as carpenter's glue. This adhesive looks and behaves virtually like white glue but generally is yellow in color, drying to a translucent white (a brown version is available for mending dark wood).
Clamp pieces within five minutes after applying glue. Setting takes about an hour, complete curing about 18 hours. The sign of a strong glue joint on wood is a uniform line of excess glue along the entire seam between glued pieces.
Although excess glue can be wiped away with a wet cloth or sponge, doing so can cause glue to enter any bare wood surrounding the joint, making finishing difficult. Experienced woodworkers usually let the excess glue harden and then carefully scrape it away with a knife or chisel.
Select epoxy when joining metal, china, glass and dissimilar materials and when a waterproof bond is needed on wood. Epoxy is a two-part adhesive consisting of a liquid resin and a hardener that solidifies it.
Epoxy is extremely strong, takes from five minutes to overnight to set depending on type and does not require clamping. In fact, it even fills gaps between ill-fitting pieces. However, epoxy must be mixed carefully to the proportions listed on the label and is difficult to remove after setting has begun (use acetone, found in some nail polish removers). Removing epoxy is virtually impossible after it's fully cured.
Traditional clear cellulose cement is still a good choice for mending many lightweight objects of wood, china and glass, and also for most fabrics and some plastics. For extra strength, apply a thin coat to each surface being joined, wait a few moments for the glue to become gummy, and then apply a second thin coat before joining the pieces and clamping them. Setting takes about two hours, full curing about two days. Use tape to clamp awkward objects such as dishes; for support, insert them partway in a bowl filled with sand.
Better than cellulose cement in most cases is cyanoacrylate, or super glue. Two kinds are available; use the gel variety for porous materials such as wood and fabric, the liquid for non-porous materials such as plastics, rubber and metal. Both kinds set in 10 to 30 seconds, forming an extra-strong bond that dries clear.
Because super glue hardens so quickly and is so strong, avoid getting glue on your skin. Do not point the container toward your face when opening it. Quick application of acetone may remove super glue, but once hard, super glue cannot be dissolved.