gel-coat curing

[idkfa]

I've catalysed some tooling gel at 0.5%, normally use 1% in this temperature but was using a larger quantity in a pressure pot. Its been a week, I've wiped with mek and it is still like toffee. A sample left out in the sun is not any better. Will a heat- gun help? or is it temp for time (weeks?) and not short high temp, also will high temp do damage instead of forcing a cure. tks

[The Loftsman]

Try some ice cubes, or failling that can you get the little boat into a fridge.

[War Whoop]

Why would you go at .5% !!! Dude you do not have the cat/mass to do anything, we typically spray in 90+F Degree at 1.75-2% Hot Pot and do not have a problem.

[gonzo]

1.5% is th minimum recommended for a proper cure. You can spray gelcoat with 2% catalyser and it should make it cure. It should have a wax adittive like MW at a 1:1 ratio too.

[tunnels]

Originally Posted by idkfa

I've catalysed some tooling gel at 0.5%, normally use 1% in this temperature but was using a larger quantity in a pressure pot. Its been a week, I've wiped with mek and it is still like toffee. A sample left out in the sun is not any better. Will a heat- gun help? or is it temp for time (weeks?) and not short high temp, also will high temp do damage instead of forcing a cure. tks

When all else fails read the instructions !!!
Gel coat is minimum 1.5 % for first coat and 2% if you have to second coat !! this is standard through out the world in any country .
.5 % is nothing !!!! Mix smaller quantities to spray . dont be in a hurry !! Do it properly and do it once !!! READ THE INSTRUCTIONS !!
The company that makes the stuff has printed this info for a reason !!!

[rmouton]

you should have done a test piece first when not sure of how to correctly mix . temp; humid;quantity, mix ratio's all play a part.

[tunnels]

If you want to get it off paint a hot brew over the top with a brush and press it hard to work the new coat or resin or gel into the stuff that hasnt gone off !!
Could need to do it a could of times to get all the crap off but its works !!
Never under catalyze gel coat !!! you are achieving nothing !!!

[Herman]

Ask you supplier for a retarder for polyester, and mix that in. Oh, and don't forget to read instructions on that as well.

Much used is 4-tert-Butyl-1,2-dihydroxy benzene, 10% solution in 2,2,4-trimethyl-1,3-pentanediol diisobutanoate which is produced by Akzo, they call it NLC-10. In general, a 0,1% of this material adds 10 minutes to the geltime. Do not add more than 0,4%, and add the same amount of MEKP extra, as this is being "eaten" by the NLC-10.

[War Whoop]

Herman in the states I use Hydroquinone which I mix with a solvent for Polyester Gelcoat if I need long Pot life.

[ondarvr]

For HQ (hydruoinone) use about 1 gram in a 5 gallon pail for a one minute change in gel time. Every product will be slightly different, but this will be close, don't over do it though, or you may kill the cure.

[Delane]

Had a bad experience Gelcoating my deck. The first time, not enough hardener. The second time, forgot to add the wax into the last batch. Didn't fully cure for some time and sucked up dirt and grim like a sponge. Some time later a Russian friend stopped in for detour while delivering a boat and reported that in Russia if they didn't add the wax they simply painted on a water based wood glue to seal out the o2 and then wash it off a couple of days later after it cured.

[War Whoop]

Originally Posted by Delane

Had a bad experience Gelcoating my deck. The first time, not enough hardener. The second time, forgot to add the wax into the last batch. Didn't fully cure for some time and sucked up dirt and grim like a sponge. Some time later a Russian friend stopped in for detour while delivering a boat and reported that in Russia if they didn't add the wax they simply painted on a water based wood glue to seal out the o2 and then wash it off a couple of days later after it cured.

You can do the same with PVA also you make a second coat with the wax added.