So I’ve only been making surfboards for a couple years now and I make a lot of mistakes. I usually console myself with the fact that most are somewhat fixable. Today I may have found one that is not?
I glass with epoxy and use a scale to measure by weight. I usually put my scale in a box lid to keep glue off my workbench. Well, my box lid disappeared after the wife cleaned up (this is how I blame her for the whole thing). I got a new box lid but didn’t notice that it wasn’t flat. So my scale wasn’t on a hard surface and not working correctly. It did seem like I was putting a lot of hardener in the cup but I consoled myself that I was using a scale. Anyway, I think I used about 25% too much hardener. I really don’t know. I got the board laminated but it was gelling pretty fast. So what will the final effect be? Is it like putting in too much catalyst in poly resin. It will be more likely to crack? Thanks for any info…
Yeah. It’s different than poly. More hardener does not necessarily mean your cured resin will be harder or more brittle. In fact, with many epoxies you can have the opposite effect. Some of the old school polyamide based epoxies actually take advantage of this and recommend different ratios depending on the desired hardness. (More “hardener” actually would yield a more flexible cured product.)
Like rooster said, if it’s sandable without totally gumming up your sandpaper, you’re probably fine.
Even though I don’t use epoxy for surfboards anymore I always have West System or something similar around for boat projects and such. I use pumps to dispense the epoxy. You can get 2:1, 3:1 and 5:1 ratio pumps depending on which resin system you are using. Its foolproof and its easy. I know people like to debate measuring by weight vs volume but generally that’s a bunch of bla bla bla. Its a simple ratio regardless of how you get there and the bigger epoxy shops even use a larch single stroke pump or motorized system that works on the same principal to properly dispense the resin at the proper ratio.
The real issue isn’t weight vs volume it is a problem of accurately measuring in small batches. The smaller your batch the more critical your measurements become and the harder it is when people use mixing cups to try and measure. When measuring liquids it is terribly inaccurate to measure in a wide cup. To get it right you really need to measure in a narrow graduated cylinder. Science class 101. https://www.msnucleus.org/membership/html/k-6/as/scimath/3/assm3_5a.html If you do need to do small batches use syringes to measure your ratios in CCs or MLs. Its foolproof too…just don’t mix up your syringes.
If you ever find yourself stuck with too much hardener in a batch, split the stuff into smaller batches, or dump it into a larger, wider container. The resin creates heat as part of the chemical reaction. Smaller, thinner batches generate less heat. Heat accelerates the ‘kick’ time. Cooler batches go off slower. This will extend your working time so you don’t have to panic.
thanks everyone. It sanded fine and I fill coated the deck today. disaster averted! For some reason the wife was not taking responsibility for this mishap.