Gelcoat didn't quite cure

I need a little help. I was repairing my center console- the console part. I filled holes with epoxy, rolled on a Duratec vinylester surfacer/primer, then a layer of polyester gelcoat that I waxed so it would cure. All that was fine, but the color match wasn't satisfactory. So I sanded the gelcoat with 60 grit, I wiped the dust off, then I sprayed some CRC brake parts cleaner on a cotton rag and wiped it off. The data sheet says it is methanol, acetone and tolulene and helptane. It was a warm, sunny dry day out- maybe 85F/20-25C and low humidity.

The next gel coat batch I made up I tinted with gelcoat tint, waxed, and added the supplied MEKP per the schedule, maybe 10-20% hot- according to the label. 1/4 ounce per pint (16 ounce), so a bit under 2%. But I saw zero bubbling when I mixed it. I suspect the MEKP was old...

It rolled out fine, but 24 hours later it hasn't yet fully cured, despite some sunlight. It has a hard (ish) skin, and did so after an hour, but it hasn't become fully hard. I figure I have a 15-20 mil/ .35-.5mm coat. Other than lettign it bake in the sun all week, is there anything I can do to help it along? Purchase some more MEKP or MPO and wipe it on the top? I really don't wan to sand this off- the color match was spot on. Can I roll on another hot layer with fresh MEKP? Should I just wait and see what a week in the sun does?

 

If it hasn't cured by now it won't and coating it with another layer or wiping something over it isn't going to help, you will still have a poorly cured layer of gel coat.

Removing what's on there and doing it again is the only good solution.

 

You can give it some heat, not more than about 70C (whatever that is in F's?) If it doesn't harden in 10min it won't ever..

 

After 1 week, I smeared it with cream BPO. That seemed to work on one area. But I had a limited amount of BPO. Smearing it later on other sections provided negligible benefit. I will continue my love affair with the random orbit sander...

 

Another one !!

just have a look at all the differant products you used with that job !!theres hardly one really thats compatable with another .
brake parts cleaner!! for God sake !! who know what sort of residue it leaves on the surface after its dry !!
Measuring catalyst is 15 ml minimum for each 1 kilogram of gelcoat . and mixed well !!.
if the coat you put on is not hard in 2 hours its never going to harden in a month of sundays .
How old is your gelcoat ??
always write dates in tins of bottles !! its real important !!
time has a habit of simply passing by completely unnotices !!
if the catalyst is old get rid of it and get some fresh stuff !!, write the date on the bottle and keep the bottle in a cool dark place then it will last for 6 months or so ,sunlight kills it ! any older than 6 months throw it out . always use fresh . its faulse ecconomy keeping chemicals ,just in case !!

 

Normal gel coats aren't formulated to cure with BPO (although they can be formulated to), so it shouldn't really help much. Removal is the only option.