Surviving the Cold Weather Caulking Blues!

by by Casey F. Robb, CSI, CCPR

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It’s that time of year, again, when “old-man-winter” has stretched his reach deep into the south!! If you live near Atlanta, we refer to this as, "from summer to winter" without even a fall!

As some of you may be aware there is a great potential to have problems with sealant installations around cold weather applications. During this time of the year neutral cure silicone sealants are preferred, as they are basically unaffected by the cold temperatures, even below freezing.

Typically cold weather presents several problems for organic sealants, such as polyurethane’s, due to their inherent nature to "stiffen" or become harder in cold weather. Most sealant installers have experience with many of these "application issues" which create additional cost and headaches. The following list will demonstrate some of the more common application issues heard:

  • As demonstrated by most organic sealants, stiffening will inhibit the sealant from "wetting-out" many building substrates. During the tooling process the installer assumes he is getting great adhesion. Yet cool surface temperatures will speed-up the stiffening process and create the potential for premature adhesion loss, down the road.
  • Many 2-part organic sealant manufacturers produce a "cold weather" or "winter" formula to speed up the mixing and curing process. This results in added confusion to an already complex 3 part mixing process, (base, catalyst, & color-pack). If the installer mixes too much, they don't have the pot life to use it, even the next day, and face the cost of disposal. If they mix it too little, that cost money too, because everyone will finish early that same day.
  • Many sealants, both organic and inorganic, require primers for adequate substrate adhesion. Most primers for organic sealants are film-forming coatings that are often difficult to install properly during cold weather.
  • In an attempt to use some organic sealants in cold temperatures, a common heating device known as a "hot box" is used before mixing or gunning. Hot boxes have to be maintained at a cost to the installer. Often, the process to heat the material will create excess moisture upon contact to the cooler substrate. This excess moisture can cause adhesion problems a few days or perhaps months later.
  • A generator is sometimes needed to power the equipment used to mix and heat organic sealants. Fuel to power the generator is expensive these days and adds to the cost of the product. If the contractor does not have a generator, or power at the site, they have to mix in the shop what they need for the day.

Many sealant contractors employ various methodologies to try and remedy this situation. Many will wait until the spring to install the organic sealants or switch to silicone. For the daily cold weather caulking application, silicone sealants are the basic "no brainer". This is one of the main reasons that neutral cure silicone sealants were chosen to be installed on the Alaska Pipeline, and many other cold weather environments in extreme climatic conditions.  Of course, we always hear, “Atlanta is mild during the winter”. Maybe it was last year!

There are some basic points to remember when using neutral cure silicone sealants during cold weather applications. When temperatures get near or below the dew point, frost point, or 40 degrees F and lower, all surfaces to be contacted must be clean, dry, and frost free. Avoid the use of open flame, torches, heaters, or blow dryers as this may cause problems with hydrocarbon build-up or moisture condensation on substrates, once they cool. All surfaces can be cleaned with solvents that are soluble in water such as IPA or MEK. These two solvents are more appropriate to use during cooler temperatures as they help remove condensation and frost and will help “dry-out” the substrate.

No sealant should be installed immediately following or in anticipation of snow or rainfall. If unexpected snow or rain occurs, document this area so that field adhesion testing can be completed on the potentially affected areas in about 2 weeks later. Typically, neutral cure silicone sealants are not water-based products and can be used in cold temperatures, even if below 32 degrees F, without excessive thickening. In colder temperatures, the cure rate of silicones may be slower because lower humidity levels that can accompany extreme cold. This will affect the cure rate, as most silicone sealants require moisture in the atmosphere to cure. Silicone sealants that are installed in colder temperatures will ultimately cure to the same physical properties as they do when applied in warmer temperatures and higher humidity. By combining technical resources with the good judgment of a qualified installer, it is permissible to caulk in cold weather. We just hope it warms up again soon and we get rid of those cold weather caulking blues!

Casey Robb is a Territory Sales Manager for Dow Corning Corporation. Although the climate where he lives is not as severe as in other areas, his concerns are shared by all.

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