I am currently in the intrieum phase of building another canoe. I unfortunately (or fortunately?)
made the mistake of reading the instructions. It said
not to use the epoxy unles the temp was going to be over 70 degress for 24 hours! I had always been under the impression that all colder temps did was give you longer working and cure times. Should I worry?
Probably Not - For a While, at Least///
– Last Updated: Feb-11-12 10:48 PM EST –
If the mix ratio is right, and then temp isn't extremely low, it should cure eventually. It obviously depends on just how cold it is - I'd go for it in the 60's, but not in the 40's. It's a good idea to get a non-flame source of heat on it - I've tented plastic sheets over saw horses in a chilly basement, and used a small electric heater or or a heat lamp to speed up a cure on the kayak I was working on.
that’s been my experience …
– Last Updated: Feb-11-12 11:11 PM EST –
...... colder temps. make it take longer to acheive initial set , and full cure takes longer as well .
Recently used a 1:1 - 5 min. epoxy to glue a small piece of Ipe to the back of the nephews Jon boat so we could screw the transfucer onto it .
We did this in the dark at night , the temp. was about 40F. and so was the aluminum hull . Took about 20 mins. before the small piece of wood could not easily be moved by hand pressure (although it stayed right where we put it w/o sliding off immediately - a vertical application) . Got down to about high 20's over night . It was solid as a rock by 5am. when we headed out fishing ... it's still stuck on very strongly , no problems .
But if I were building a canoe and epoxy was a major component , I would do the epoxy work in temps. as near 72F. as possible .
It would probably work just fine in colder temps. , but I wouldn't want to find out otherwise the hard way . If mfg. says a certain temp. range is required for best results , then I wouldn't deviate from that on an important project .
I know epoxies are formulated in quite a variety of ways and perhaps the brand you are speaking of just won't perform well at lower temps. regardless how long of a set time is allowed (??) . It may set up and cure in the colder temps. , and take the expected longer time to do that ... but the strength may be severely weakened due to the colder than recomended temps.
The notion that ambient temp has to be
over 70 degrees for at least 24 hours seems like someone’s obsessive-compulsive way of driving boat builders crazy. I’m sure I’ve violated that rule, and I’ve never suffered any consequences. In my opinion, it is important to have the ambient temperature at least at 72 degrees for the first hour, but by that time the epoxy (at least the West 105/205 I use) will have set substantially and amine blush evolved to the surface. After an hour or two, if the ambient temperature drops below 70, it is no big deal.
I have used an infrared lamp to help certain jobs along, but one must be careful about outgassing. I prefer to warm the wood before the glass and epoxy goes on, and let it cool slowly.
Your epoxy may not mix properly
At lower temps the mixing is just as fussy as the cure. Keep a light on your epoxy/curing agent while working to warm it.
I would also suggest contacting the manufacturer and see if a low temp curing agent is available. Some can extend your temperature window to the 40°s.
BTW, it takes a long time for a light bulb to bring the temp of epoxy up. If you can, bring it in the house while not using it.
don’t worry, read more
is that 24hrs before you can handle a glued piece of wood? There’s a range of epoxies with different rates of cure. If it’s too cold some joints won’t be strong enough for handling in 24 hrs or hard enough for sanding in 24hrs. If it’s too cold the epoxy is viscous and doesn’t make for efficient, neat glassing. Some slow epoxies won’t have a hard cure for 4days at 60degrees. It all depends on what you need to do in the time allotted. If you want to move things along quickly then having a steady temp above 65degrees with medium cure hardener will suffice.
If you’re working at 55degrees you might as well use fast hardener for joints but don’t bother doing laminating/coating until it’s warmer.
use the right hardener
There are different hardeners for different temps. At least with West System, I know that if you are well below the temp range the epoxy will not kick for a very long time. I once filled some holes in a sailboat when it was in the 40s or so, figuring that I was in no hurry, and it would go eventually, but it took many days! And it sagged in the meantime. That was with the -05 series epoxy.
Boat builders are very particular about temps, and will tell you that the right temperature affects the ultimate strength of the layup. The guys who did the repairs on the MIT sailing team race boats would heat the shop up to 85 or 90 degrees when working with epoxy, because they wanted it to cure as fast as was practical, for the best strength.
Also some Epoxy boats are cured in an oven after being layed up to get the best, most complete cure.
BP … Call me anytime on this stuff.