Scott Yellig wrote:More than anything I would like to find a way to work when the weather is cold. Here and now on April 3rd it is 35 Deg F (2 Deg C). None of the adhesives or epoxy I have can be used. Pumping and mixing epoxy would be great if it worked in the cold.
The Gougeon Bros say: "Use WEST SYSTEM 205 Fast Hardener. 205 Hardener has been designed with a polyamine system that cures well at temperatures as low as 35°F. Keep in mind the extended cure time required before removing clamps or sanding.
"1. Warm the epoxy resin and hardener with heat lamps or keep it in a warm area until you are ready to use it. You can build a small portable hot box out of rigid sheets of foil-backed insulation, with a regular light bulb or an electric heating pad inside to maintain a temperature of 70°F–90°F. This method allows you to keep the warm resin and hardener close to your work and allows less time to cool off between dispensing and application.
"2. Warm epoxy resin and hardener before using. As mentioned, the warmer the resin and hardener, the lower the viscosity. Thinner resin and hardener will flow through pumps better, cling less to containers and mixing equipment, and mix more thoroughly. The initial chemical reaction will get off to a better start and result in more cross-linking even if the mixture cools after it is applied to a cooler surface. The thinner mixture will initially flow out smoother and wet-out porous surfaces better. Warm the epoxy resin and hardener with heat lamps.
"3. Dispense epoxy resin and hardener in the proper mixing ratio only. Altering the amount of hardener will seriously compromise the epoxy’s ultimate strength. WEST SYSTEM Mini Pumps are designed and calibrated to dispense the correct ratio—one full pump stroke of hardener for every one full pump stroke of resin. If you are not able to warm the resin and hardener, do not use excessive force when dispensing. Keep steady pressure on each pump and allow each pump head to make a full stroke down and a full stroke up. Remember, the resin and hardener become thicker and more difficult to pump when they are cold.
"4. Stir the epoxy resin and hardener thoroughly. Mix the resin and hardener longer than normal (two minutes minimum) and scrape the sides and bottom of the mixing container. Use a mixing stick shaped to reach the corners of the pot. For a given volume of resin and hardener, a smaller diameter mixing pot will improve the chemical activity because the limited surface area will not dissipate heat produced by the chemical reaction.
"If you are unable to warm the resin and hardener, allow the mixture to stand in the pot for several minutes before using. This induction period will help get the epoxy’s chemical reaction started.
"5. Warm the epoxy bonding surface as much as possible. The epoxy will thin out as it is applied to a warm surface. It will flow out much smoother and penetrate better, resulting in a stronger bond. Warming can be done by constructing tents around small areas and heating with portable heaters, warming the area with hot air guns, hair dryers or heat lamps. Small components or materials (such as fiberglass cloth) can be warmed before use in a hot box as described in above. Avoid unvented open-flame heaters that burn kerosene or fuel oil. Unburned hydrocarbons have been known to contaminate bonding surfaces, and elevated moisture and CO2 levels may inhibit epoxy’s cure. Catalytic heaters do not appear to pose a problem unless they’re used in a confined space such as a curing tent or box.
"Another temperature-related problem occurs throughout the year, even in warm climates, when overnight temperatures drop well below daytime temperatures. The daily variation in temperature may cause moisture contamination problems if epoxy is applied to an exposed structure or surface too early in the day. A hull, for example, that has cooled overnight may remain colder than the surrounding air until the afternoon. Water vapor can condense on the cooler surface and affect the adhesion and cure of epoxy applied over it. If the bonding area cannot be heated, allow the surface and the surrounding area to come up to air temperature before applying epoxy.
"6. Prepare surfaces carefully between epoxy applications. When coating at cold temperatures, the slower cure can result in the formation of an amine blush on the surface. The blush feels like a waxy film on the surface of the cured epoxy. Just before applying subsequent coatings, wash the surface with warm water using a 3-M Scotchbrite™ pad. Before the water evaporates, dry the surface with plain white paper towels and sand any remaining glossy areas with medium grit sandpaper.
"7. Allow the epoxy additional cure time before removing clamps or stressing joints. As a general rule, double the cure time for every 18°F drop in temperature. Allow extra time for pre-stressed joints and joints that will be subject to high loads.
"8. Post-cure the epoxy if possible. Post-curing can help to complete the epoxy mixture’s cross-linking and boost the epoxy’s physical properties even after a week or two of cold temperatures. Post-curing simply is the process of applying heat to complete or speed the cure after the epoxy has reached a partial cure at ambient temperature. Elevate the temperature of the epoxy and substrate gradually to avoid thermal shock. Although any temperature elevation will improve cross-linking, try to boost the temperature to room temperature (72°F) or warmer. The time required depends on the hardener used, the post-cure temperature and how much further the cure has to go. Generally, higher post-cure temperatures require shorter post-cure times. Do not exceed 140°F and do not remove clamps or load the joint until after the final cure. CAUTION!—Heating a porous material may cause air within the material to expand and “out-gas.” If an epoxy coating applied over the material has not gelled enough before starting the post-cure, bubbles from the out-gassing material may show up in the cured coating. Allow the epoxy to reach a partial cure before post-curing.
"A variety of post-cure techniques can be used. In some cases, your shop will naturally warm itself enough to complete the cure during the day, following a cold night. Outdoors, building a plastic tent to trap solar heat can easily boost the temperature enough for post-cure even during cool weather. Turning up the thermostat, using radiant heaters, electric heaters or electric blankets are the most common way to control the post-cure temperature in a shop. It is not necessary to heat the entire structure if you are working on only a small area. Tents of plastic or insulated board are very helpful for confining heat to specific areas and provide greater mobility with a limited heat source, both indoors and outdoors."
I used epoxy in the winter in Nova Scotia, on an unheated boat, when the Bras d'Or Lakes were frozen to a depth of several inches. I came to the conclusion that I muc preferred it over Cold Cure. Drilling a 1mm dia hole in the handle of the containers holding the resin and hardener, is worth while. This allows the container easily to replace the air taken out when you pump out liquid. Check the tap on the hardener to ensure that there is no build up in the nozzle. Did you know that WEST system hardener is water soluble? This makes the pumps very easy to clean and it is worth doing this every few weeks. (Generally, it is the hardener pumpt that clogs up, rather than the one in the resin.)
Good luck!