Been learning to fix dings the last few months. Super fun, except for dealing with the caps on my resin tins. Always wrestling to get them off; I have to use pliers. Eventually the caps get too dented, and I can’t use them anymore.
Anybody know any tricks to prevent this? I’ve tried wiping down the threads and the inside of the cap with acetone, but it doesn’t seem to work.
Better yet, maybe I should just transfer everything to a different container? Any air-tight and UV-preventing plastic would be good, right?
Try smearing a little cold water wax on the threads of the can/container, work the cap on and off a couple times. That should leave a wax film on the threads of the can and the cap that the resin won’t stick to. Clean off any resin dribbles before reclosing. Repeat the wax as needed or just because you feel like it.
Many hardware or paint stores sell empty pint, quart and gallon metal paint cans . You never know what was in some random plastic container. And there’s no threads on a paint can to trouble you down the line. Store in a cool, dark place.
Something to think about- if it’s doing that, your resin might be getting towards the end of its shelf life. That gets ugly.
Wow, this is great stuff guys. Thanks! I’ll implement ASAP.
So Doc, how long does resin typically last? Currently I’m using what I have for practice, so it probably doesn’t matter that much. Found an old, beat up board that I whack with various objects and then try to fix.
When I start working on actual good stuff, I’d like my resin to be on-point.
As my old Ethics professor used to say; that depends.
In this case, it depends on how you treated it, how hot or cold it’s gotten during its life, how big a can it is (and how much air is in the can), how long since it’s been opened, how long you’ve had it, unopened, how long it sat on a shelf in your local shop before you bought it, how long it sat in a warehouse before that… and more. You should be able to rely on it for six months to a year if you treat it well.I have gotten longer, but sometimes that bit me too.
Right? Should is the operative word. The best you can do is treat it well yourself. Place I worked at was seasonal, and no, we didn’t pitch last year’s ding repair kits every spring. Some of it went bad. We eventually stopped selling repair kits because of that.
The moral of that story is buy small quantities unless you are in the repair biz and using a lot.Yeah, it might be $10 for a pint of resin ( I’m just using arbitrary numbers) versus $20 for a quart or $40 for a gallon, but if all you use is a pint before it goes bad it’s not that economical to buy larger quantities.
Also, catalyst (Methyl Ethyl Ketone Peroxide or MEKP) is a relatively fragile molecule, heat and sunlight break it down faster than resin. The good news is that while it varies in strength, it’s the same stuff whether you get it from a surf shop, hobby shop or boat place if yours goes south on you.
Resin will solidify over a period of time. Depends how long it sat on a shelf before you bought it, but typically it will solidify sometime in the second year. If you pick up the can, shake it etc. It lasts longer. I have heard all sorts of stories and speculation about MEK, but I found a 16 oz.bottle a couple of years ago that had been in storage for ten years. I decided to use it just to see if it still was any good. It was. So I used it up.
My stuff isn’t even a year old, so I think I’m pretty good. I keep everything in a styrofoam cooler in an attempt to buffer temperature swings. Not sure if it makes a difference, but my workshop is in an attic that gets hot in the summer.
Ummm- I would keep the cooler in the cellar. Not the attic. It’s not the speed of temperature change that’s the issue.
Chemical reaction speed (like resin breakdown) typically varies with temperature and it’s not linear, more like exponential. As well, polyester resin goes off by (pretty much) breaking the ends off molecules which join up to make longer molecules, Catalyst accomplishes that but so does heat, UV and oxygen ( air). The 40°F or more difference between ambient temp in a cellar and ambient temp in an attic in summer will make a difference.There’s also other things in resin (styrene monomer thinner, for instance) that will tend to evaporate/cook out, not to your benefit.