Polyester resin cure temp?

[klos]

I work on my fiberglass prodjects in a pole barn that is not insulated. I turn the heat up to about 60 deg. while I'm working. Then after all the fiberglass lay-up I try to get the heat up to 70 deg. for 30-45 min. just enough to start the cure. After that I turn the heat off to about 40 deg. I am wondering if that will affect the strength after completely cured. Thanks.

 

[Chief101]

Re: Polyester resin cure temp?

You should be fine, the resin will make it's own heat when catalized above about 60*. Make sure the resin and the work is heated and like I said once the resin starts to kick off it will make it's own heat.

 

[ondarvr]

Re: Polyester resin cure temp?

Yes, it is recommended to not drop below 60* when it is curing, the resin needs heat to complete the cure process and finish cross linking. The colder it is the less cured it is, it can be heated later and will cure more but not as well as if it was cured correctly the first time. Plus as it gets heated later it will start to move and shrink again, this does not always cause problems, but you can see the effect on boats that were made in the winter, then exposed to the sun later, you will see glass patterns or other defects in the surface profile. But, many people do it every day and get away with it, it's just not the best way.

 

[klos]

Re: Polyester resin cure temp?

What I'm realy worried about is in the jan. & feb. months it gets down to the single digits. For best results how long should the heat be left on?

 

[BillP]

Re: Polyester resin cure temp?

Remember this. Polyester continues to cure after it "kicks" (gets hard to the touch). The initial kick is most critical and the final cure not as critical. It's like concrete. It gets most of the hardness immediately and gets harder with time. Last time I check polyesters they needed to kick within a few hours and final cure was approx 30 days. If the initial kick is too long the resin never reaches it max potential barcol hardness. Use heat, extra hardner or a "hot" coat to help it along in low temps. I've pushed the limits down the the mid 40F range and did ok. It is almost impossible to over catalyze polyester and damage strength. Catalyist make the required heat when no other sources are available.