Why is a hot car different from post-curing?

Don’t exactly know, but my guess would be that the temp can get too high in a car standing in the midday sun.

I postcured my first (blue foam) XPS/epoxy board on a shelf sitting over a fireplace, lots of hot dry air with temps around 35-40 degrees celsius.

Haven’t had a ding yet in my board after using it for almost a year, not even a dent in the deck.

And so far no delamination/outgassing problems either.

My board was glassed with 6+4 on the deck and 6 oz bottom using SPsystems SP115 epoxy. Hotcoated with 2 part Pu

laquer SP ultravar 2000.

I’ve never measured, but my guess is it’s too hot. No circulation doesn’t help either.

In the hot car, if the used board has any mosture under the skin…

Don’t leave pets or pet surfboards in cars, temps can reach 160 F or 70 celsius if left in the sun.

Suppose we’re talking about a freshly made board. If I’m wrong please correct me but I seem to remember Greg L. or somebody mentioning the benefits of post-curing around ten to twenty degrees higher than the temps the board will see in regular use. So let’s say you stick your board in the car early in the morning and make sure it’s well supported. As the sun comes up, the temperature in the car rises fairly slowly to an early afternoon peak of what, 120 F, maybe 140 F. So you leave the board there until it cools down in the evening, effectively letting the cure temp ramp up and down at a gentle pace.

Of course this is all theory. Tomorrow I’m gonna stick a digital thermometer in my car to see how hot it gets.

Anyway, I was just wondering.

Later,

Andrew

you can use a hot car for post curing, but it must be done within a certain time frame. once epoxy is fully cured a temp range is established for the epoxy. there is a word for it but i can’t think of it right now, any how if you go around 40 degrees above the cured temp the expoxy will soften… so say you let you board cure at room temp, 70 degrees, at 110 the epoxy will soften… a car can easily get over 110 inside… now say you postcure your board in the 120degree car (big problem is it is usally not hot for long enough) now your baord can easily withstand the hot car for the rest of it’s life… there is are a few threads about this in the archives, greg and bert often talk about this subject… i rember bert talking about the dangeres of postcuring too early as well, one of the reasons why he does his post curing under vac…

No control, that’s why. We put a thermometer inside a car once and it hit 180+. In the window I think you could have boiled water. Also as stated above, no circulation. Yes, I’ve actually done it with the heater on in the sun and then moved to the shade to cool down. But you have to carefully moniter what your doing. I’ve seen the results of not doing it right … not pretty.

Hey all,

Excellent responses. That’s all I wanted to know. Thanks for all the feedback.