How wood adhesives and glues are affected by cold winter temperatures

The drop in temperatures during the cold season affects both the wood and the materials used to glue or finish it. Materials are made to perform perfectly within a certain temperature range, and going outside the range influences the behaviour and decreases the qualities of the finished product. Wood is also influenced by low temperature, and its behaviour is different from that at 18-20°C, the recommended range for the workspace. We have talked about the behaviour of finishing materials in winter here. This time, wood adhesives and their behaviour in cold weather are the subject.

The nature of the adhesive and its limitations

A first classification of wood adhesives can be made according to the nature of the resin solvent and from this point of view they are divided into water-based or water-thinnable adhesives and organic solvent-based adhesives. According to their chemical nature, adhesives used in the wood industry can be polyvinyl, polyurethane, epoxy, cyanoacrylate, ureic, ureo-formaldehyde, melamine-formaldehyde, resorcinic, etc. The last 3 categories in this list are adhesives used in the production of chipboard, MDF, OSB and other wood-based panels. They are used on large capacity industrial plants where working parameters are strictly controlled, so their behaviour near 0°C is not of interest. The others, however, are frequently used for gluing wood in factories and workshops, where temperatures can sometimes reach freezing point.

Water-based adhesives are affected by temperature drop because water freezes at 0°C. For wood, the most commonly used water-based adhesives are polyvinyl, or aracite type. In the past urea adhesives (urelites) were used, but due to the low guarantee of ready-to-use adhesive or difficult preparation, they were gradually replaced by aracite, urelites remaining in the panel industry where preparation is automated and behaviour controlled. Araceites are aqueous dispersions of polyvinyl acetate. The reactive groups that cause bonding float in water, and when the water is removed, they react with each other. If the temperature is very low, the water gradually freezes, the groups come together and react with each other, with the adhesive still hardening in the can. That's why the storage and transport temperature, not just the temperature in the hall, must also be above min.5°C to make sure that the adhesive is not damaged.

There are also aracet adhesives that withstand repeated freeze-thaw cycles. One such adhesive is TISZABOND D3D 3010, distributed by the company Szolvegy from Tirgu Mures. The adhesive can withstand temperatures as low as -20°C and can be used after thawing. After such a cycle the viscosity of the adhesive is likely to increase. It is recommended to mix in the drum until it becomes fluid again. However, you should be aware that even adhesives with special properties cannot withstand more than 3-4 freeze-thaw cycles. If it does not become fluid again after mixing, the adhesive is totally compromised and can no longer be used.

Solvent-based adhesives such as polyurethane, are not directly affected by the drop in temperature, i.e. they do not freeze. Their behaviour when glued, however, is affected by the low temperature. The hardening of polyurethane, epoxy and similar adhesives occurs through a chemical reaction. It is well known that all chemical reactions are faster at higher temperatures, their speed decreasing with temperature. There are even specialists who say that the reaction rate can double if the temperature increases by 10-15°C, but I have not found any studies to prove this. It is accepted, however, that reactions work better at higher temperatures. Low temperature can lead to increased working time or incomplete reactions and poor quality solder.

At the time of gluing, the temperature of the glue, the wood and the environment should be similar

In the bonding process it is not only the temperature outside or in the working environment that is important. The temperature of the adhesive and the wood at the time of gluing are equally important. Wood that has come straight from the warehouse or that has been left overnight in an unheated workshop cannot be glued immediately. It must be allowed to acclimatise and reach the temperature recommended by the manufacturer for quality gluing, above 10°C. One phenomenon that occurs in cold winters is a drop in air humidity. As a result, some of the water in the wood will come out, lowering the moisture content of the wood. If not allowed to adapt to the environment, the wood will absorb the water-based adhesive inside, reducing the amount left in the contact area. This results in weak glues that yield easily.

Adhesives should also be allowed to come to room or workshop temperature before bonding. Even catalyzed or solvent-based adhesives, where it is believed that they can react even at low temperatures. A chemical reaction needs active energy. Below a certain temperature, this active energy decreases greatly and the reaction slows down and tends to stop. I know, there are adhesives that react anytime and stick anything, but we're talking about professional wood adhesives, the kind commonly used in factories and workshops, not for a DIY project.

Minimum film forming temperature

There are situations when the temperature in the hall or workshop cannot rise very much on cold winter days. There are counties in the country - Brasov, Harghita, Covasna, Suceava - where the outside temperature can reach -30°C. In these conditions it is difficult to ensure a decent temperature, especially in storage areas. If you don't have the conditions, it's best to avoid stockpiling in warehouses as much as possible and only order the amount of adhesive that can be safely kept in the warehouse. And make sure that adhesives are transported in climate-controlled vehicles.

When the temperature is very low, however, at least a minimum working temperature must be ensured to avoid sticking problems. In the case of peanuts this is minimum film forming temperature TMFP. It is around 5°C for most of them. But there are also variants, mainly used by those working in construction, for which the MFWR goes down to 0°C. Not infrequently, workers have to remove snow from wood in winter before gluing. Adhesive TISZABOND D3 WINTER is formulated to work in such conditions. It has improved wet adhesion, a 0°C TMFP and increased frost resistance, which ensures quality bonding in winter.

If need be, products that also work in extreme conditions can be found. It is good, however, that this way of working is not a constant, but only happens because of extreme outdoor conditions. Quality work is achieved when working conditions are good and the temperature in the hall is above 15°C in winter. This process also involves operators who work hard at temperatures below 10°C. To preserve the quality of your products, you also ensure good conditions in storage and transport, not just in the hall. In connection with TISZABOND products, Szolvegy provides transport with air-conditioned machines, so that the adhesive has 12 to 14°C on delivery.