Friday, June 14, 2013

How Much Do You Know About GLUE?

Thank you to:

Woodworking Glue Quiz:
  1. All glues are the same; they all work on wood. - TRUE or FALSE
  2. There is not one great glue that will do it all. -TRUE or FALSE
  3. All white/yellow glues are the same. - TRUE or FALSE
  4. Yellow glue is strong-White glue is only used by schoolchildren. - TRUE or FALSE
  5. There is no glue like the old hide glue. - TRUE or FALSE
  6. Aliphatic glue is superior. - TRUE or FALSE
  7. Formaldehyde glues are waterbased. - TRUE or FALSE
  8. Water based glues are harmful because they will swell and twist wood. - TRUE or FALSE 
  9. Thick glue is better and fills gaps and voids. - TRUE or FALSE
  10. More glue is better. - TRUE or FALSE
  11. More pressure is better. - TRUE or FALSE
  12. More catalyst is better. - TRUE or FALSE
  13. No glues will take a stain. - TRUE or FALSE
  14. Mechanical help such as biscuits or dowels is needed for best edge gluing strength. - TRUE or FALSE
  15. Miters and other end grain can be glued with any thick glue. - TRUE or FALSE
  16. Moisture content is important; gluing air dried lumber is not a good idea. - TRUE or FALSE
  17. Pieces should be assembled as soon as possible after spreading the glue. - TRUE or FALSE
  18. There are glues that will set in 3-5 minutes allowing very fast edge gluing of hardwoods. - TRUE or FALSE
  19. It's OK to machine immediately from press/clamps. - TRUE or FALSE
  20. Heating the glue line will not speed the cure. - TRUE or FALSE
  21. "Water Resistant" on the label means the glue isn't affected by water. - TRUE or FALSE
  22. Glues with toxic chemicals in them shouldn't be used. - TRUE or FALSE
  23. Water based glues can be used as long as the temperature in the shop is above freezing. - TRUE or FALSE
  24. Shops don't need to be humidified in the winter. - TRUE or FALSE
  25. It's OK to glue bowed, bellied or twisted stock as long as it's pulled tight with clamps. - TRUE or FALSE
  26. Glue performance can be easily tested in the shop. - TRUE or FALSE
  27. Powdered glues that require water for mixing are more likely to bleed through veneers than PVAs. - TRUE or FALSE
  28. Glues last forever; there is no shelf life. - TRUE or FALSE


1. False There are hundreds of different adhesives formulated for thousands of different applications. Choosing the correct glue for your project could determine its eventual success or failure.

2. True Although many glues have multiple applications there isn't one that can "do it all."

3. False White and Yellow glues (Poly-Vinyl Acetates) are formulated with different viscosities, solids contents and chemical modifications, for different applications.

4. False Color has nothing to do with a glue's strength or quality.

5. False There are few, if any, applications in which synthetic glues, such as PVA, can't outperform, hide glues.

6. False "Aliphatic" simply describes a broad family of organic chemicals that includes PVAs.

7. True Formaldehyde glues, although they have different chemical components, are water based just like PVAs.

8. False Most commonly used wood glues are water based and will not harm wood if high solids glues are used, assembly times allowed, and spreads are controlled.

9. False Many applications require a glue that is not thick. Although there are adhesives available that have gap filling qualities, just because a glue is thick doesn't mean it is capable of filling gaps and voids.

10. False Actually, too much glue can result in a thick glue line and, hence, a weaker bond.

11. False Too much pressure could result in a starved glue joint and a weaker bond.

12. False Catalyst levels depend on the glue and specific catalyst formulations. Some catalysts speed cure as they are increased; others slow down the cure rate.

13. True Although some glues appear to take stains better than others, there is no glue that is stainable.

14. False Using mechanical fastening devices when edge gluing tends to weaken the glue joint by disrupting a smooth true edge joint that will provide maximum strength. Devices such as biscuits or dowels should only be used to maintain alignment or to add strength in miters and butt joints.

15. False Gluing end grain may require sizing before gluing and the use of a high solids glue.

16. True Ideal moisture content for gluing is 6.8%, therefore, higher air dry moisture should be avoided. Higher moisture levels also result in wood movement after gluing with accompanying checks and splits. Lower moisture content may interfere with the glue's ability to properly wet the surface.

17. False Often, it is better to allow the glue to set for a little while before applying pressure.

18. False Although there are glues available that will set quickly, strength is often sacrificed.

19. False Regardless of the glue used, it is a good idea to allow it to cure for 24 hours before machining.

20. True When using conventional PVA the cure rate is not affected by heating the glue line, in fact, bond development may be slowed.

21. False Only glues that are "Waterproof" such as Resorcinol Resin will provide absolute protection from moisture.

22. False Most glues are made with some chemicals that may be considered toxic. With normal precautions, most glues are completely safe to work with.

23. False Although many glues are "freeze/thaw stable" many do not perform well at low temperatures.

24. False Many shops become excessively dry during the winter causing numerous gluing problems because of resulting moisture loss from the stock.

25. False Often, gluing bowed or twisted stock results in undue stress on the glue joint and glue lines that are either too thick or starved of adhesive.

26. False Because of the myriad factors involved in gluing and testing, the only way to accurately measure glue performance is through a laboratory testing facility.

27. False Once reconstituted, powdered glues actually have a higher solids content than many PVAs, and therefore are less likely to bleed through veneers.

28. False All glues have a definite shelf life after which their performance deteriorates significantly.