Temperature considerations for poly

[mckevin]

It's the time of year that the question must be asked...
How cold is too cold to poly? The project is coming along, but I am quickly running out of indian summer.

I saw this question addressed below re: epoxy and gluv it, but can't find anything about poly, and search doesn't seem to be my friend...

 

[andy6374]

Re: Temperature considerations for poly

Once it starts getting cold add about 20cc of MEKP per quart of resin. This should surely cure with the aid of a heat lamp.

 

[neat]

Re: Temperature considerations for poly

I will say that under 55 will be too cold to do laminating work with Poly.

 

[klos]

Re: Temperature considerations for poly

I don't like it to get under 60 in my shop. and keep everything the same temp. during layup.

 

[ondarvr]

Re: Temperature considerations for poly

60* is the reccomended minimum temp for poly, but it can be used at lower temperatures and still work OK, not great though. In production post cure is the biggest problem at cooler temps, post cure is when the part is taken out of the mold and is not completely cured. As the part continues to cure out of the mold the surface can distort and become uneven, this is most evident when the part is a dark color and then it's put in the sun. When used as a reinforcement or repair the under cured laminate will not be as strong as one cured at a higher temperature.

 

[andy6374]

Re: Temperature considerations for poly

In production post cure is the biggest problem at cooler temps, post cure is when the part is taken out of the mold and is not completely cured. As the part continues to cure out of the mold the surface can distort and become uneven, this is most evident when the part is a dark color and then it's put in the sun.

This is even a problem for boats that had a full cure in optimal temperature environments. Awlgrip flag blue can reach temps as high as 212 F in the sun (info per awlgrip rep. ) and this can cause post curing on a 25 year old boat. Print thru is pretty much unavoidable for dark colored hulls that are constantly in the sun