Cold weather epoxy use - wood

Expectations in using “fast” systems where heat will be a challenge to properly cure material? Are overnight sub-40/50 degree temps too low to expect and overnight cure? Bonding joints, glass laminate (couple layers of 10oz), etc....

Are there systems out there capable?

 

Welcome to the forum.

There are some fast hardeners that will cure in those temperatures, but at the low end of the scale, 24 hours may be a little tough. All of the usual marine "room temperature cure" epoxies will suffer from this. It will cure, just not very quickly, unless you can raise the temperature. In cases like these, it's usually best to locally raise the temperature, with non-flame heaters and a tarp or two. You'd be surprised how much you can raise the temperature, with a spaced off the work tarp covering the area. Get a good seal around the edges and against the floor to improve its effectiveness. I don't generally suffer this issue, but in the winter I sometimes need to tarp something. I have several $20 oil filled electric heaters (WalMart) that can make temperatures under the tarp over 70 degrees in freezing over night temperatures. The last time I needed this was last winter and I was doing a new transom. The boat had to stay outside, so I tarped the whole boat, put a few 2x4's around the perimeter to seal it to the ground and placed a heater just behind the transom on the ground. A thermometer showed mid 70's in the coldest portion of the night and the goo had kicked off the next day. These heaters are typically about 1,500 watts each on full heat, so you'll need separate 120 VAC electrical circuits or they pop breakers if using more than one, on the same branch circuit.

 

Great response and thank you. There’s always a concern in never gets out of that second stage though and will be brittle though, right?

 

Brittleness is a function of (mostly) hardener additives and resin formulation, so no, it wouldn't get brittle. In fact, it may be pretty pliable, until a full cure (enough heat and time) have come and passed. I know many northern builders that just "plow along" knowing their goo's haven't fully cured, but have gone tack free, with enough grip to keep things mostly were they need to live, until the spring, where they wheel them outside and get a complete thaw and cure. A black tarp in bright sun helps a lot too. I can't wait this long, so I force the issue with heaters.

 

I have folks (professionals) building a 72 foot commercial schooner using our basic no blush epoxy with fast winter cure. They are using it outdoors in temps down to 30 degrees. They have used well over 100 gallons (of slow, fast and regular curing agent). - All epoxies take a week or more for full cure but fast cure epoxies in low temps are probably ready to sand the next day. - I have built a number of kayaks with with epoxy in my unheated garage in mid winter in New Hampshire. - see epoxyproducts.com/noblush.html

 

I have done small areas with epoxy in those temperatures using hair dryers. Pretty boring, but on a small area; you can get work done outside. Make sure and bring a music box and a friend to laugh at you while you stand there. Beer helps, too, but then only one hair dryer. Stick with faster epoxies.

For larger areas; talk with Paul or heat the area.

 

Paul is correct, at least a week for full cure, though possibly longer, depending on formulation. This is true of all room temperature cure epoxies. Now, this said, if you have reasonable temperatures, you'll get 90%+ cure within 24 hours, while the remaining 10% or so take another several days to fully setup. Hair driers sounds like making a career out of curing epoxy. I've used heat guns on occasion, particularly using the hot on hot method, but sweet God a hair drier. My arm would fall off no where near the time necessary to get a cure. That takes a lot more dedication than I have. In the end its the heat you need, for sufficient enough time. I glad I don't have to go through this anymore, but I have the opposite, needing it to be cool enough.