Winter temperatures are more critical than we think

Soudal Technical Manager, Steve Loveridge speaks about the very real effects of dropping temperatures.

As we hit the frost crunching days it is worth remembering that the teams building on our sites will start to see a significant change occur in terms of curing times for adhesives, sealants, membranes, and coatings. Quite simply many of these products will start to take longer to cure given the less-thanideal ambient temperatures that hit much of the country for large portions of the working day.

As a rule, the curing rates expressed in product technical data sheets are based on a “stable, consistent” temperature over a 24-hour period. This may be the case in Rarotonga, but it isn’t in Queenstown, Palmerston North, or Auckland. The reality for us is that as temperatures drop, curing rates also drop until we get down to 10°C at which point the curing process effectively hibernates and goes completely on hold. Understanding that a slow-down of the curing rate is logarithmic (not constant), as opposed to linear (constant) means careful thinking onsite is required when fixing various construction elements.

To this point, we have been discussing the ambient temperatures, but it is equally important to remember the physical substrate temperature and that the lowering of this can contribute to both slower curing and reduced bond strength of the adhesive/sealant to the surface – most particularly with damp/wet or frost bearing surfaces. There are solutions and mitigators in play in other parts of the world such as stabilised heating sources, but these are not commonplace in New Zealand.

Added to all of the above, construction teams have one final hurdle when using MS & PU (elastomeric) sealants as the physical gunning of the product becomes slower and more difficult without the direct use of “hot-boxes” or an alternative method to slowly warm up the cartridges/sausages – again not commonplace here in gods own. While none of the above issues are new – they are frequently forgotten in the collective haste to get projects and jobs pushed through as quickly as possible. An appreciation of the issue from both a specifier and contractor perspective will ensure jobs are done within a realistic timeframe and more importantly to a quality standard that understands and manages product risk appropriately.

Understanding that a slow-down of the curing rate is logarithmic (not constant), as opposed to linear (constant) means careful thinking on-site is required when fixing various construction elements.

For more information on curing rates or technical advice on sealants, foams and adhesives, please contact Steve Loveridge on 021 273 8894 or visit our website to see our comprehensive product range and technical data www.soudal.co.nz/ products/

This Tech Tip was supplied by NZCB National Partner Soudal. Soudal are a key supplier of sealants, foams and adhesives to tradies under our iconic Gorilla brand. For over 30 years Gorilla Grip, Foam, Glues and Silicones have proven their quality, reliability and technical performance in kiwi conditions. www.soudal.co.nz