Epoxy resin question

[jaxflg8r]

I am doing some re-building on my 19 foot caravelle, including a stringer replacement, and new deck.

I am using the West Systems Epoxy with the Slow hardener. Weather here is fluctuating. with daytime highs at 78 on Saturday/Sunday and close to freezing nighttime lows. The slow hardner says must be above 60 degrees.

I am working outside in driveway.

Question: Is there any harm to putting down the mat/resin when it is below 60 in evening and letting it cure next day when temperature goes above 60?

Also found out the hard way that you do not leave mixed epoxy resin (in mixing cup) in the direct Florida sunlight....Started smoking.....

 

[oops!]

Re: Epoxy resin question

as far as the smoking cup....you mixed in too much hardner....

hit it with flood lamps after you glass it..

 

[erikgreen]

Re: Epoxy resin question

Potentially... the chemical reaction between epoxy and hardener has to occur in a certain temperature range. It's possible to get an incomplete cure if you keep it too cold.

I'd consider just getting a faster hardener for those cold nights and use the slower one during the day. The faster hardener will heat up more and quicker and compensate for temperature issues.

Erik

 

[erikgreen]

Re: Epoxy resin question

as far as the smoking cup....you mixed in too much hardner....

hit it with flood lamps after you glass it..

Actually with epoxy you get the same results as long as it's within 5% of the amount you want.... more or less and it just won't cure properly. This is different from poly resin where adding heat will cure it, and you adjust the cure time by changing the amount of hardener.

The smoking bit happens when you leave the epoxy in a cup in heat... the limited surface area of the cup vs. the volume of epoxy and heat generated starts a vicious cycle... the heat can't get out, speeds the cure, which generates more heat.... I've melted cups that way.

You can counter it to a point by keeping your epoxy in a painter's tray instead of the cup, or some other wide shallow container.

You can also limit the amount you mix at a given time.

 

[Coors]

Re: Epoxy resin question

Go the the Boathouse, and try the MAS they have. I think you will like it better (and cheaper).

 

[jonesg]

Re: Epoxy resin question

Actually with epoxy you get the same results as long as it's within 5% of the amount you want.... more or less and it just won't cure properly. This is different from poly resin where adding heat will cure it, and you adjust the cure time by changing the amount of hardener.

The smoking bit happens when you leave the epoxy in a cup in heat... the limited surface area of the cup vs. the volume of epoxy and heat generated starts a vicious cycle... the heat can't get out, speeds the cure, which generates more heat.... I've melted cups that way.

You can counter it to a point by keeping your epoxy in a painter's tray instead of the cup, or some other wide shallow container.

You can also limit the amount you mix at a given time.

True, it can burst into flames if theres enough of it in the container too long, I find the best solution is to get it on the work or mix in smaller batches to suit the pace of work as you said.

 

[jcsercsa]

Re: Epoxy resin question

Hi there , us composites has 5 gallons for 230 , hope that helps John

 

[stefcia]

Re: Epoxy resin question

Hi. us composites has 5 gal resin + 1.5 hardener(medium) = 6.5 gal for $ 230.

 

[External Combustion]

Re: Epoxy resin question

Putting down resin below temperature and waiting for the ambient temps to rise will allow some sags and runs that you may not expect. Otherwise it will work. If you have any questions the boys at West Systems are quite helpful.

Personall I prefer West Systems over MAS. Obviously some differ.