Will Polyester resin eventually cure fully if applied below 60 degrees?

[sbklf]

The instruction sheet I picked up from my resin supplier says that "applying resin below 60* may cause resin not to thoroughly cure". I applied some yesterday in 50* weather and it seemed to harden OK but is gumming up the sand disc today.

Is this a partial cure I am seeing due to the temp? If so will it harden up in time?

If it does not harden enough to sand properly should I re-do it?

I am use to working with epoxy not affected by temp. One more question about poly, How long can I wait between layers and still get a chemical bond with polyester resin?

 

[ondarvr]

Re: Will Polyester resin eventually cure fully if applied below 60 degrees?

The reason for the 60* recommendation is because polyester needs heat to cure well, if there's not enough heat it will be under cured, you may never notice it though.

What type of resin are you using, some have wax added, this will allow the surface to cure well and be sandable in a few hours.
Without wax it may take a very long time (if ever) before you can sand it without gumming the paper. Don't go over the recommended Catalyst % and if needed use some kind of heat, heat lamps work, but need to be kept at a safe distance, they can easily over heat the laminate if they're too close.
You should be able to brush some fresh resin with wax added over what you've already done and be able to sand it, remember the need for heat.

As long as the surface is sticky you should be safe to put another layer down without any other prep work. If you have waxed resin you need to put the next layer down before it becomes tack free and depending on the temperature that may be less than an hour. If it does cure completaly, then it needs to be sanded and cleaned before the next layer is applied.

 

[sbklf]

Re: Will Polyester resin eventually cure fully if applied below 60 degrees?

I am using boatyard resin without wax. I was sanding to feather an edge for another layer of glass. Thank you for the tip, I will use wax in the resin I mix to fill the weave.

 

[drewmitch44]

Re: Will Polyester resin eventually cure fully if applied below 60 degrees?

I know this isnt helpful to you, but i use the resin from wallyworld. Its the bondo brand. I know its got a bad rap but i just work slow and it works ok for me. And ive been using it at 40 degrees and its cures. Just some info i dont know if its healpful at all. Im not good with others i learned with the bondo and i stuck with it. Maybee it takes more time cause of small applications but i glassed my whole floor with it and made a splashwell for my friends boat and it went well. His splashwell you can stand on and it is solid as steel. Sometimes i use the Elmers brand from lowes. Its the same as the bondo. Maybee i spend more on that stuff but i dont know where else to get it or what type to buy.

 

[sbklf]

Re: Will Polyester resin eventually cure fully if applied below 60 degrees?

After three days now it is still has an ever so slight tack on the top. It is not structurally important enough to re-do so I will leave it, sand it best I can and go over it. In the meantime I am installing heat in my garage. One step foreward and two back like always. Thank you for the replies.

 

[ondarvr]

Re: Will Polyester resin eventually cure fully if applied below 60 degrees?

At three days with low temps and a tacky surface you're still safe for a very good bong without sanding. If you do try to sand it, use a very course grit like 36 or 24 on a grinder, anything less and you're wasting your time.

Some of the answers you got in the other forum are a bit strange.