Glues & Adhesives

According to historians and archaeologists, adhesives have been used for thousands of years, probably since Stone Age cave dwellers first applied bitumen to stick flint axe heads to the tops of their wooden hunting spears. In ancient times, people made their glues from whatever they found in the world around them, such things as sugar, fish skins, and animal products boiled in water. The Egyptians have been using hide glue since around 2000 BC. They have used hide glue mainly for furniture. There are also records that Romans used animal glues for wood.

We still use some of these natural adhesives today, though we’re much more likely to use artificial adhesives made with chemicals. It’s obvious modern glues are chemical products from the horrible names they have, polyvinyl acetate (PVA), phenol formaldehyde (PH), ethylene vinyl acetate (EVA), and cyanoacrylate (“super glue”) to name just four. Many modern adhesives are called synthetic resins for no other reason than resin; the gooey substance found in pine trees and other plants was one of the first widely used adhesives.

When PVA adhesives were discovered the use of hide glues plummeted. Hide glue is still used today, although it’s limited mostly to furniture and musical instruments. Hide glue cures at room temperature and creates a very strong bond. Since the adhesive sets by cooling to room temperature, high temperature will prolong the setting time and make it slower. Hide glue is known to be brittle and breaks fairly easily on stronger impact. It probably won’t resist high pressure. 

PVA glue (Polyvinyl Acetate), this was first discovered in 1912 by Doctor Fritz Klatte in Germany, so it has been around for quite some time and over the last century it has become very popular, as it is used in a wide variety of applications. Polyvinyl acetate can of course be used to make glue, but it has many other uses as well, such as in the automobile industry for one. However polyvinyl acetate as an adhesive was not used until the early 1950s.

PVA glue is most frequently used in woodworking today, sometimes referred to as white glue. PVA glues can easily be cleaned up with water, making it easy to clean off any excess adhesive from whatever you’re working on and is applicable to a wide range of projects. Aliphatic resin glues are another type of modified PVA glue derived from the polyvinyl acetate polymer. They’re often referred to as carpenter’s glues or yellow glues because of their wide use in woodworking and the fact that many varieties dry yellow. 

What is interesting to know about PVA wood glue and aliphatic resin wood glue is that they both work in more or less the same way. Remember that both of these types of glue are technically water based. Therefore they work by evaporation. In other words, once the liquid glues are dispensed from their tubes or containers, they cure by allowing the moisture to evaporate from them. As the moisture evaporates, it only leaves behind the other components, either the aliphatic resin or the polyvinyl acetate, which in essence forms a layer of rubbery plastic, or very similar to plastic anyway. Both of these types of wood glue will work on all types of wood. 

Something to keep in mind is that PVA wood glue and aliphatic resin glue both don’t dry and cure very quickly. It takes quite some time for them to dry, and it’s of course because water takes time to evaporate. When it comes to PVA glue and aliphatic resin glue, you’re going to want to clamp the pieces together for at least an hour or 18 hours under tension after having applied the glue. Depending on the environment, it can take up to 24 hours or even longer for the PVA glue to completely cure. Due to the long curing time of this glue material should not be touched before the curing is complete or else it may compromise the integrity of the bond.

In general, basic PVA wood glue has the ability to hold up about 300 pounds of weight per square inch, which is not too bad, although when compared to polyurethane glue that can hold upwards of 3,500 pounds per square inch, and two part epoxies that can hold upwards of 6,000 pounds per square inch, wood glue is decidedly weak. With that being said, aliphatic resin wood glue is a fair bit stronger than basic PVA wood glue. What is however very important to know is that wood glue does stay fairly flexible when it dries. This is of course very important because it means that there is a good deal of impact resistance present. PVA glue is not toxic but does not work well on non porous materials; it requires a bit of texture in order to form a solid bond.

Professor Dr. Otto Bayer invented polyurethane’s back in the 1930s. He was a scientist and doctor who worked with plastic, doing lots of research in terms of the properties and possible benefits of various plastic types. With that being said, in terms of being used as glue or adhesive, polyurethane did not become popular until the last 20 years or so.

Polyurethane glues are a type of moisture-activated glue that foams and hardens into an extremely resilient adhesive as it dries. One part polyurethane glue requires moisture and a little bit of heat in order to cure. Once the components are exposed to moisture, the curing process will begin and as the curing process happens, a little bit of heat is created, which also helps to spur on the process. In terms of the working time that you have at your disposal, you have about 15 minutes to work with this type of polyurethane glue.

The most important thing that you need to know about this kind of glue is the fact that it is super toxic and carcinogenic when it is in its liquid form. Under no circumstances should you get that stuff on your hands, and you definitely should not ingest it either. Even more interesting is the fact that although this stuff is super toxic when in its liquid form, when it is completely cured, it is 100% food contact safe. 

Another interesting thing to note here is that polyurethane glue is very flexible and therefore is ideal to use in applications that require impact resistance and a bit of movement capability. In terms of its applications due to its versatility and ability to stick to both porous and non-porous materials. Polyurethane glue is very strong in terms of strength when compared to other glues, it is definitely up there with the best of them, but one type of glue that polyurethane glue is not quite as strong as is epoxy, particularly two component epoxies.

Polyurethane glue has a very limited shelf life, when it is open, moisture can get in and cause the glue to set quickly, furthermore clamping under severe pressure can cause glue squeeze, resulting in all the glue being squeezed out of the joins, resulting in more glue on the floor rather than in the joins.

Epoxy or epoxy resin was first discovered and patented by Paul Schlack of Germany in 1934, epoxy uses epoxides and amines to form a solid bond. Another type of epoxy glue, Bisphenol A (BPA) was discovered by Pierre Castan of Switzerland in 1943. So this type of glue or adhesive has been around for a long time. The typical formulation of epoxy includes a hardener in addition to the resin that it is mixed with. When the components are combined, a chemical bond is formed. This bond, once it has hardened, is watertight and fills in any gaps. Even though some epoxies take a long time to cure, they are some of the most powerful wood glues on the market. 

Resin is a glue that is obtained as the final product after mixing raw epoxy resin, a solvent, catalyst and hardening agent. The odor of the resin glue is pleasant. It is available in the market as liquid and powder. The drawback of resin glue is its drying time. It takes about 8 to 10 hours to dry. However, the warmer the temperature the earlier it dries.

A single inch of epoxy, if you use the right stuff, can hold up 6000 pounds or deal with 6000 pounds of impact force. In terms of structural integrity, hardness, impact resistance, and weight bearing capabilities, two-part epoxy and one part epoxy are both up there with the best of them. Moreover, epoxy is actually also one of the best types of adhesives across the board, as it has extreme moisture resistance and is completely waterproof.

In order to cure resin glue the temperature must be above 21°C to 24°C. The air temperature needs to stay above this temperature for the entire drying time. As we live in Scotland the answer is to cure your resin in a warm oven. A 65°C toaster oven is excellent for helping resin to cure faster. The only downfall is in order to cure the glue draws any moisture from the timber and further time in the oven reduces the moisture content even further, resulting in very dry timber, the glue also dries very hard and rigid.

You can’t always trust the way products are marketed. Some wood glue is waterproof, while others are water-resistant. Waterproof means that water cannot penetrate the glue and cannot cause it to deteriorate over time if it is in constant contact with water or moisture. Water-resistant means repels water (or moisture) to a certain point. If the glue is exposed to water for a longer period, after some time, the water will slowly soak into the glue, causing it to weaken its bond. 

Wood glues generally have the following indicators added by the manufacturers that will indicate just how waterproof the glue is. These are the indicators to look for and what they mean.

ANSI/ HPVA Type 1. This indicator shows (Type 1) that the wood glue is pretty much waterproof under all circumstances

ANSI/ HPVA Type 2. Type 2 indicates that the wood glue is considered water-resistant in most cases 

Type 3. These should be used for indoor applications only 

From this you can be assured at Tanera Camans we have applied rigorous testing to find the best manufacturing techniques and best sourced material to ensure a quality product. You will see camans made from special formulated glue in play from Bute in the south to Caberfeidh in the north and from Lewis in the west to Aberdeen in the east. Maybe even this year they’ll have a big part in helping to win the Scottish Camanachd Cup.

Stick Care Section Shinty World

On July 12, 2019, DELO lifted a 3-axle truck in the air. The 220 t truck-mounted crane used for lifting extended its arm 40 meters into the air. Additional concrete slaps were used to increase the truck’s unladen weight of 13 tons to a total of 17.5 tons.

The name of the world’s strongest adhesive is DELO MONOPOX. This epoxy resin forms a very dense network during heat curing. A special filler was used among other things to modify the resin properties in order to achieve the extreme strength required for the world record. This made it possible to lift a weight of 17.5 tons with only 3 grams of adhesive.

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