> Hi, I just finished joining a set of scarfs with East Systems epoxy
> hardened with fist cold weather hardener. The joints are clamped and
> curing now. The total cure time is 7 days according to the label. Do I
> have to keep them clamped for that whole time or can I take the clamps off
> before that time. What is the earliest that they can come off. I am in
> Toronto and the temperature is 10celcius (I think it's 40 farenheit)

> Thanks,

> Paul

10 degrees Celsius is 50 degrees Fahrenheit.

Usually the epoxy sets up (hardens) in a few hours, but develops more strength as it is allowed to cure. With time and heat the molecules of the liquid resin link together (polymerize) into a strong solid plastic.

I'm not sure of the particulars on this particular epoxy, but if it has not yet set up, I think that if you can raise the temperature to 20 to 25 degrees Celsius ( that would be 68 to 77 degrees Fahrenheit -- roughly `room temperature') then after a few hours you can take the clamps off and the cure will continue on its own, strengthening over time.

To do this I's get a couple of 100 or 150 watt light bulbs and put them in fixtures that I could place close to the joint. I'd like them about 0.5 m or 18 inches above the joint. If, after 20 minutes, that doesn't warm the area sufficiently, move them closer. You are not going to warm the winter's chill with something like this, but it should be enough to give those few added degrees.

A cheap fixture for this is made from a lamp socket (You can usually find these in hardware stores for around a dollar) at the end of a length of electric cord. An aluminum foil pie plate, with a hole punched in the center, fits loosely over this. When you screw the light bulb into the socket the pie plate should rest loosly on the bulging areas of the light bulb, directing more heat and light down on your work area. Money saving tip: I have bought electric cord and plugs for making these devices, and frequently find the cost of the plug and wire adds up to more than the cost of an inexpensive 6 foot extension cord (which has a plug already molded onto one end) -- so I get the cheap extension cord, cut off the end with the socket(s) and replace that with a lamp socket. If you can get a 9 or 12 foot extension cord at a reasonable cost you can put one lamp socket at the end, and another about a meter (3 feet) away, and make a two-light device for little more than a single light one.

Hang your lights from a 2x4 supported above the area you want to warm. you can use sawhorses or rungs on a step ladder to achieve the desired height. Some string or duct tape will hold the wire in place, and the bulbs can dangle beneath this.

By the way, besides being nice for spot warming, you can use these things -- with or without the pie plate reflectors -- to add some light to dark areas of the shop, or, replace the bulbs with something weaker (40 watt to 25 watt) and you can lower the string of lights into the dark recesses of the bow or stern of your boat when you want to inspect things (leaks or repairs), or need some added light while you attach miscellaneous hardware (hatch brackets, foot brackets, tie-down pads for floatbags, etc.)

Hope this helps.

Paul Jacobson