I don’t know why but I’ve been having issues with my tooling gelcoat. I’ve always had the issue of “aligatoring” no matter what I do. From what I gather its a problem with not completely cured gel coat, but I give it extra time beyond what the manufacturer says. I’ve tried to slightly over catalyze with MEKP, but then it will lift in concave areas. It just seems like even doing exactly what the manufacturer says I will have an issue one way or the other. I just want to be able to pop a mold off with out any extra post work. So is there really a difference between tooling gelcoat systems? Like is the more expensive stuff worth it? Right now I use US Composites 404 tooling gel and resin system. I’ve made a bunch of molds with it but would like something a little more user friendly. Any input would be appreciated.
Likely because you are spraying the gelcoat on too thin. Are you using a mil gauge to check wet mil thickness when spraying? When you laminate, the resin bites in to the gel coat if too thin. Other than that, could be you start laminating too soon. You shouldn’t start until you can touch your finger to the gelcoat without it sticking to your finger
I am not using a mil gauge. Maybe I should. I’ll do a fairly heavy pass with my gelcoat cup gun. Its tough cause sometimes I’ll do a mold in the summer when my shop is in the 90’s F, and like now my mold room is in the mid 60’s F. I know temperature has something to do with it but I can never nail down the correct ratios and times.
Ask your supplier if they know what the promotion levels of the gelcoat are. I used to use a tooling gelcoat a few years ago, which like you, I always suffered from alligatoring. I always thought it was something I was doing wrong and eventually changed to the vinyl ester tooling gelcoat that I use today. I found out a couple of years later that my supplier had dropped the product because they were getting loads of complaints about it not curing properly and alligatoring. When they investigated, it turned out the manufacturer was consistently under-promoting the product which meant it just never cured properly no matter what you did.
It would be odd if it turned out to be the same issue for you, but it is something that can happen.
You may have already checked these but make sure you are mixing resin and catalyst thoroughly, make sure temperature is consistent as possible between spraying and laminating, make sure multiple gelcoat layers are the same thickness and catalysed to the same extent and make sure you’re spraying at the correct time if doing multiple coats / subsequent laminations.
Thanks guys. Being winter in my area, my layup room is a bit cold but I keep it around 66F, but the mold surface might be a little colder. I started a spreadsheet to document room temp, mold surface temp, keep track of times, mix ratios, even the humidity of the room. If a company made a tooling gelcoat that was much more user friendly I would buy it in a heartbeat.
If you can get hold of Reichold tooling gelcoat, give it a go. It’s the most user friendly stuff I’ve come across, I’ve never had it alligator once no matter what user errors I throw at it.
Thin gel is far and away the most likely problem. You should be putting down 22-24 mils wet as a minimum. Some tooling gel mfg’s suggest up to 40 mils laid down in two sessions but I’ve never done that. If you get below about 12-15 mils, gators are a distinct possibility.
Get a mil gauge. I’d be dollars to donuts, you’ll find your problem.