Wood adhesives or glues for wood are used to achieve a firm and durable bond between two pieces of wood. There are many adhesives, based on products from different sources, both chemical and natural.
Types of wood glue
Traditional carpenter or reversible glue
This traditional glue was obtained from various parts of cattle (leather, hooves, horns, cartilage, jaws) that were boiled for hours or days uninterruptedly, until a very thick gelatin with an intense animal aroma was obtained. The gelatin was spread on a wire mesh and allowed to dry. These plates were ground and the powder soaked.
The mixture was boiled in a water bath and kept at a constant temperature for use. In order to use it, the parts to be joined should be cleaned, which should be free of dust, grease or any foreign element.
The pieces were assembled fairly, passing the hot glue, joining the pieces and pressing. They were left pressed until they cooled and were perfectly dry. The bond was firm and durable, although not as strong as other more current options, and deteriorates with moisture.
Comparatively, this weakness may seem like a handicap, but it need not be. Let’s think about restoring high quality furniture with fine woods or musical instruments that need to be repaired. In these cases, you cannot use wood adhesives that can damage the elements if it is necessary to dismantle a part.
It is similar to carpenter’s glue, but with less adherence and slower drying. It consists of a granulated powder that is glued with water, which can sediment and liquefy according to your convenience.
This glue has a light other color, is applied with a brush and pressed until dry and hard. It was used a lot to glue cardboard and paper. It has less grip than a carpenter’s, but is less brittle. It tends to mould over time, so preservatives are added.
A glue based on casein, a milk substance. By coagulation, the whey is separated from the milk and the dough (curds), without salt, is dehydrated (the result looks like a piece of dry cheese). It is ground and incorporated with borax, which facilitates its dissolution in water.
White wood vinyl glue
There is a wide variety of white glues, with different densities and drying characteristics.
These are made from water-soluble vinyl resin. When drying, the vinyl components tend to stick together. A very thin layer is used, but the pieces must fit perfectly. It dries very quickly, about an hour, and becomes transparent. It is not waterproof.
It is one of the most used glues to glue, perhaps not because it is the best glue for wood, but because it has an excellent quality / price ratio.
Glue or aliphatic resin glue
Also known as yellow carpenter’s glue. It is, together with vinyl glue, one of the most widely used wooden glues in the carpentry world today.
Dries in 15 minutes and is non-toxic. More resistant to water and heat than white adhesive.
Some brands offer versions of wood glue that are water resistant after drying, suitable for outdoor use and even for indirect contact with food. For this reason, they are most used in making toys and / or kitchen utensils, such as cutting boards.
Although this type of adhesive is used in a multitude of fields, in the case of wood it is mainly used to lay veneers or to join wood with other less porous materials.
These are mainly polyurethane-based adhesives. Drying times are usually between 30 and 45 minutes, although accelerators are available to reduce these times. They are water resistant.
Epoxy resin adhesives for wood
It is an effective but unusual solution, at least in traditional carpentry.
This type of adhesive is usually formulated based on two components, resin and hardener, to which pigments can be added. The resulting mixture is an adhesive with great resistance, both to abrasion and to water. The drying time varies widely depending on the manufacturer and type of product.
Nowadays they are widely used to fill and color wooden pieces to make tables and other types of furniture.
Silicones are not a good option for gluing wooden pieces.
Recommendations and frequently asked questions
What if the wood is very wet?
The first thing to consider is that excessively damp wood changes its volume, so it is preferable to wait until it reaches an equilibrium moisture level.
In addition, the effectiveness of some adhesives, especially those based on water, such as aliphatic or vinyl glues, will be reduced and drying times will be delayed. In these cases, it would be preferable to use polyurethane wood glue.
What if the clothes get stained?
It depends. Water-based adhesives can be washed if the quantity is not high and immediately cleaned with plenty of water.
With other adhesives, solvents or acetone should be used. But be careful, the solvent can further damage your clothes.
Is there any kind of professional wood glue suitable for toys and food?
In this case, there are aliphatic resin adhesives suitable for this type of use. Can be used to glue wood and make toys, cutting boards, turning (bowls), spoons, etc …
Tails can be colored
As already mentioned, epoxy adhesives can be colored with a wide range of specific pigments.
Water-based glues can also be colored with water-based paints and even food coloring. The proportion of pigment must not exceed 5% of the total. You should also consider that, once dry, there may be slight differences in tone, so it is always advisable to try beforehand.
Respect the manufacturer’s specifications
Preparation temperature, application and preservation, viscosity, drying times, etc. Otherwise, the result may not be what you expected.
Defects derived from poor application are much more common than those from a defective product.