Recent bouts of unseasonal weather got me thinking about the effect of atmospheric conditions on the use of adhesives. Over the past few years the UK has seen snow in April and a heatwave in October both of which would have an effect on adhesives that may have been unexpected.
The industry accepted temperature for epoxy adhesive use is above 10Â°C. At temperatures below this the reaction becomes slow or may not proceed at all. A general rule for many epoxies is that for every 8-10Â°C increase in temperature the cure rate is halved and for every 8-10Â°C decrease in temperature the cure rate is doubled. For example, if an adhesive has a pot life of 10 minutes and a cure time of an hour at 23Â°C, at 33Â°C the pot life would be just 5 minutes and the cure time 30 minutes. This could cause practical issues on site as a short pot-life may result in material going off before it can be used, resulting in waste. Equally low temperatures may also cause a practical issue. Taking the previous example, if the temperature was 13Â°C the pot-life would be 20 minutes and the cure time 2 hours, which would mean the bond would have to be left longer before it could be moved which would decrease productivity. Epoxy adhesives that cure at low temperatures are available and should be considered by those looking to use adhesives outdoors or in poorly heated warehouses.
Another climate factor that effects the use of adhesives (particularly epoxies) in the construction industry is rainfall. Generally, contamination of adhesives with water will have a detrimental effect on the cure rate and degree of cure. Therefore, most adhesives cannot be used outside whilst there is precipitation. Furthermore, some adhesives are intolerable of damp substrates, in these cases materials that are outside during wet weather must be left until completely dry before they can be bonded, which will hold up construction significantly. In extreme or prolonged cases of bad weather construction output overall decreases and this has a profound effect on the use of adhesives.