What do you know about adhesives? Here is a quiz that will test your stick-to-it-ness. Anyone scoring 19 or more correct is a super-dilly sticky person.

Questions:

  1. Basically, all glues are the same in that they all stick to wood in the same way. TRUE or FALSE
  2. Yellow PVA glues are stronger than white PVA glues. TRUE or FALSE
  3. The term "aliphatic" on the label indicates a better adhesive. TRUE or FALSE
  4. Most adhesives with formaldehyde catalyst are heat curing. TRUE or FALSE
  5. A thick glue-line is almost always better than a thin one, as it will fill gaps and voids. TRUE or FALSE
  6. Higher pressure is better, as it squeezes the glue deep into the wood. TRUE or FALSE
  7. Some glues will stain just as well as wood. TRUE or FALSE
  8. Dowels or biscuits greatly increase the strength of a well-made edge-to-edge joint. TRUE or FALSE
  9. Moisture content affects the rate that a PVA glue joint cures. TRUE or FALSE
  10. The temperature of the wood affects the rate that a PVA glue joint cures. TRUE or FALSE
  11. The temperature of the glue affects the rate that a PVA glue joint cures. TRUE or FALSE
  12. When edge-gluing, the pieces should be assembled ASAP (15 to 25 seconds) after spreading the glue for maximum strength. TRUE or FALSE
  13. After edge-gluing with PVA in a clamp-carrier, the panels can be machined as soon as they leave the clamps (about 60 minutes). TRUE or FALSE
  14. The term "water resistant" means that the adhesive is waterproof and is not affected by submersion in water. TRUE or FALSE
  15. A few adhesives have toxic chemicals and they should not be used. TRUE or FALSE
  16. Water-based glue that has been frozen should not be used. TRUE or FALSE
  17. Low humidity in the area around the gluing operation can likely cause open end joints if the wood is a little bit high in moisture. TRUE or FALSE
  18. When edge-gluing, if a warped piece can be pushed straight in the press or clamps, it is OK to use. TRUE or FALSE
  19. If unopened or tightly sealed, glues will last for decades. TRUE or FALSE
  20. Wood surfaces, once prepared properly for gluing, can be stored and used months later, and still be just as good. TRUE or FALSE
  21. PUR adhesives are only applied with a heat gun. TRUE or FALSE

Answers:

  1. FALSE. There are at least 100 different wood glues, some similar to each other and some quite a bit different in properties.
  2. FALSE. The color has no relationship to strength of the adhesive.
  3. FALSE. The term refers to the type of chemicals in the adhesive, but not necessarily the strength of a bond.
  4. TRUE. They can cold cure if given enough time, but this is not done as standard production.
  5. FALSE. Many adhesives lose their strength when they are too thick (over 0.006 inches).
  6. FALSE. Pressure spreads the adhesive, moves the two pieces of wood closer to each other, squeezing out any excess adhesive, and fills any small nooks and crannies, but does not squeeze glue into wood.
  7. FALSE. Wood adhesives do not absorb stain like wood.
  8. FALSE. Dowels or biscuits on edge joints are for positioning. At times they may provide a slight increase in joint strength. Sometimes they result in a slight decrease in the joint strength as they disrupt the continuity of an edge joint.
  9. TRUE. Wetter is slower.
  10. TRUE. The warmer the glue, the faster the cure.
  11. TRUE. See No. 10.
  12. FALSE. Some urgency is required, but not this fast.
  13. FALSE. The joint may take 24 hours to develop its ultimate strength. Early machining can result in sunken glue joints. In a few cases, machining early can be done, but certainly not in most cases.
  14. FALSE. The adhesive can tolerate intermittent wetting.
  15. FALSE. Probably all adhesives have some degree of toxicity, but all can be safely used if label directions are followed.
  16. TRUE.
  17. TRUE. This is perhaps the leading cause of poor joints.
  18. FALSE. The warped piece that was pushed flat or straight does have a memory and therefore will be trying to warp even after the glue has set. This will put stress on the joint, lowering the ultimate stress the joint can take until it breaks. Also, where the warped piece meets an adjacent piece, the pressure can be so high it will squeeze out much of the adhesive leading to a starved and weak joint.
  19. FALSE. Adhesives have a shelf life.
  20. FALSE. Time makes wood surfaces untrue and not as active for gluing (= weak joints).
  21. FALSE. Some PURs are liquid and do not need heat.

Have something to say? Share your thoughts with us in the comments below.