Apply heat safely to epoxy?

[neilm]

What's the best way (cheapest and safest) to add a little heat to an epoxy glue-up? I have a heated garage but it's really cold out and I don't want the heater to run non-stop so I was thinking of getting some heatlamps. Are these safe? How well does the electric blanket trick work? I'm scarfing right now but I now I will need portable heat for the stitch and glue part.

Neil

[JimD]

Halogens of this sort kick out a lot of heat:

http://www.justoffbase.co.uk/core/media/media.nl?id=2786&c=317638&h=ad74030d25951769d9a5

Or other heat lamp or standard incandescent bulb. Just follow the usual saftey rules such as don't let it get too close to anything flamable.

[Thorne]

Electric blanket is said to work very well by some folks who live in very cold climates -- just use a thermometer. Use a junk blanket, probably safer than heat lamps.

[Electra]

Infrared heat lamps work just fine and can be left unattended. I've also used a 28,000 BTU portable propane heater (www.mcmaster.com Stock No. 1719K3) to cure large areas of epoxy, although you would need to move the heater frequently so as not to overheat any one particular area. I would never leave a propane heater unattended.

[John Meachen]

If you only need a little heat,a small polythene tent over the job and a light bulb beneath it may do the job.

[boylesboats]

I have uses overhead quartz heaters..
They do cover large areas with penetrating heat..
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200326086_200326086

[LeeG]

how big is the scarf? I did some gluing on 4mm ply scarfs for a kayak by putting a piece of plastic tape covered 4mm over the scarf then weighting it with a two red bricks, on top of the bricks was an iron. That heated up the bricks to 100degrees or so.

[AstoriaDave]

Neil, for laminating and gluing joints, a heat lamp at a distance such that the wood is warm to the touch, after several minutes, but cool enough that you can keep your hand there -- that's about right. For larger areas, in glueup, an electric blanket is a very good, thermostated heat source. So is a small thermostated space heater, directed at the work.

Avoid:

1. Spot heat sources which concentrate the heat in one place. You can scorch wood that way. I'm sure you can figure out how I know this.

2. Laying fill coats of resin on the surface when the work is in "warm up mode" because this will bring out trapped gases, generating bubbles or (worse) pinholes in the fill coat.

If you plan to use heat during cure, then you must preheat for an hour or so to a temp slightly above that to be maintained during cure. This causes the wood to finish outgassing before the resin goes on, and as it cools during cure, the resin is actually sucked into the pores of the wood, achieving good saturation, and eliminating the chance of any pinholes forming. This may sound tricky, but all you have to do is turn the electric blanket down a notch or two, or back the heat lamps (etc) off a foot or so from the preheat condition.

[JimConlin]

Heat lamps are fine. I would not use an unvented propane or kerosene heater because their combustion products (CO2 and water vapor if all's well) might contaminate the work or not support human respiration.

[barbaree]

I use lamps on the TBird when doing scarfs and glass work all the time because we do the work outside in the water in cold months. When its warm outside we're sailing. We'll use lamps or a heater inside to get the boat warm and we use them outside to get the surface warm to fire off the epoxy. We use tents made out of garbage bags, battens and tape if we have to. Set the lamps so the surface is warm, not hot, and use slow catylist. I use West system, but System Three works the same. warm good, hot bad.

[Tylerdurden]

I used four 100 watt bulbs under a 8' dinghy with plastic laid on top of semi hard epoxy and a blanket on that. worked fine with nighttime temps below freezing.

[denp]

http://hpim0328

[neilm]

I bought an electric blanket and it's working very well for the scarfing. Under the blanket I got the thermometer up to 105 deg F. It heats up the 9mm plywood nicely.

I want to get some heatlamps too but when I went to the store the heatlamps were rated at 250 Watt max and the only heatlamp bulbs they had were 250 Watt. That is to close for comfort so I will look around some more.

Thanks for the tips everyone! I like your ideas. It's been well below Zero out lately and my garage door leaks heat so this should really help with the utility bills.