glassing in Cool/Cold Weather

[ShipBear]

I'm patching some holes in a friends hunting boat..
Weather been up to low 60's in the day time..
Having trouble with my glass setting up.. Seems like it takes 2 to 3 days to cure.. Doing it with no heat lamps, and outside..
How cold is " To Cold " to fiberglass..?? My glass stayed sticky for 3 days, I thought I messed up Big Time, but seems OK now..
Any one got any Info..?? I guess useing a Heat Lamp would speed it up..??

Thanks, Larry

[Reese]

I'll assume it's polyester resin...

You could always use more MEK which speeds up the cure or like you said use a heat lamp.

I use those yellow flood lamps that you can get at home depot. They are very adjustable so you can point them in just about any angle. It only takes about 5-10 minutes per area to cure the resin.

[action17]

is your resin old? if not add more mekp and and stir well!! heat lamps help also!

[Scott]

Far from me to butt in but....with out a property of materials curve I would be careful playing with a forced cure via heat or additional MEK. I would take the chance on a cup holder but nothing mission critical. The chemical reaction and ratios are tested to provide the maximum strength/adhesion. It can end up being hard but brittle. Then again I'm no expert!

[Reese]

You should measure the MEK and use common sense with a heat lamp.

It shouldn't be that big a deal for small repair areas. Maximum suggested amount of MEK to resin is 2%, I have use slightly more on occasion on smaller areas with no problems.

Here is a chart of ratios:


MEKP Catalyst Ratios
PeroxideConcentration

1QT 1GAL 5GAL

1.0% 10 cc 38 cc 188 cc
0.4 oz 1.5 oz 7.4 oz

1.25% 12 cc 47 cc 235 cc
0.5 oz 1.8 oz 9.2 oz

1.5% 14 cc 56 cc 282 cc
0.6 oz 2.2 oz 11 oz

2.0% 19 cc 75 cc 376 cc
0.7 oz 2.9 oz 14.7 oz
cc=cubic centimeter
oz=ounces (weight not volume)

These calculations are based on 9.2
pounds per gallon resin and 1.11 grams
per cubic centimeter MEKP

[Reese]

The chart didn't print very well...

A 2% solution for a quart of resin is 19cc or 0.7 oz of MEK.

[Techno]

Something getting confused here is hardened or pot life and cured. It takes sometime to cure even after it gets hard. Forgot how long on poly but it's still longer than when it's hard to the touch. Heat lamp or even a light bulb to keep the local area above the temp needed.

[ShipBear]

Thanks for all the Info... I hooked up a heat lamp.. Made a
BIG Difference..!!!! Set-Up NICE.....
Like i said it's a work boat, Hunting.. Just patching it..
I would be ALOT more careful working on a Hi-Po Hull..

Thanks Again, Larry

[Superdave]

Mix my resin and lay the glass. Take regular drop light with a 60 watt bulb and hang close to the spot and watch carefully. Whan the area gets warm turn off the lamp and cover the area with wax paper. It seals the air from the resin and helps it harden. Similar to using styrene in the last coat of clear gel.
Dave

[Backfire]

It helps to be a little more precise when dealing with resin. With no stated product names or numbers is hard to be precise. Say Ashland modified polyester 9252 used by a great number of boat builders. This and most resins generally use a 1% minimum mekp (methel-ethel-ketone-peroxide) catalylist to achieve a full cure. Recommended 1 1/2-2 %, 3% and much above is over kill and and retards a full cure ever, as bad as not enough. The fact that the resin "gets hard" is no test as to it's real strenght. The fact that each product has a "gel time", or the time the catalyist is throughly mixed with the resin to the time it starts to "gel", as in get thick like jello. Maybe a minute to the point from gel, to it has formed a lump that is rapidly getting hot. A test is helpful to see what you have "cooked" up. Take a 3 oz paper cup (not a 4oz coffee cup), like a bathroom drink cup that comes in a dispenser.
Pour some of your mix in that and set aside and record how many minutes and seconds it takes to "gel". Without knowing the mfg. info, it's a guess at general standards. Many resins use something similar to this. The lab standard temperature for any info regarding performance is 77 deg. So they say gel time is 20 minutes at 2% mekp. Ok, unsaid is that it is 20 minutes at 77 deg. As any of you know that have "glassed" in the summer, at 87 deg. you half the time (-+) that you have at 77 deg. At 97 deg you have half again, or give or take- 5 minutes! Things get out of hand if you do it in the sunlight in summer- or I should say you can't get it out of your hand before that one quart waxed paper cup runs up to 350-400 deg or more and starts making noise and some vile smoke. See your auto paint store for the neat plastic paint cups. But it ain't summer now. The resin is not going to cure at 45 or 55 degs. The answer is not more catalyist, it is more heat. If you can't heat the garage or shop into the 70's, make what you are working on warm. Do note that resin gives off fumes and that styrene, the main component (nothing to do with wax) is easy to catch FIRE, as in static electricity, heat guns, heat lamps, open flames, a drop light bulb that gets broken, and worse than that is acetone. If your garage or shop doesn't have a fire extingusher so big you can hardly lift it, you need to think about what life is like in the Motel 8. A hair dryer (poor man's heat gun) works great for small jobs and patch work. Duct tape to a chair, gallon jug full of water, just to get the area warm, not hot!, to the touch then apply your whatever and keep warm for another hour or two, or maybe a light bulb over night, as some resins or gelcoats (resin with color) takes 24 hours or more for full cure. The key is TEMPERATURE AND TIME and proper catalyization. A farm store/co-op is a good place to get several syringes that measure cc's for catalyist. My favorite is 60 grit to knock the glaze off the cured layer and the little hairs to let the next layer lay down flat. I would rather use PVA, Polyvinylalcohol to seal a gelcoat patch to promote a cure rather than wax. Just wash it off with water. Check out this site for all you need minicraft.com A Big shop vac keeps the dust down and fumes if you rig up a hose long enough to keep it outside and the hose in the boat. I run out of paper, Y'all have fun.
Backfire ;)