Hi members! I’ve read the (very) informative epoxy archives and learned quite a bit. (for example, this forum provided the approach i’m going to take when i glass.)
but i have some specific questions i’m hoping you can guide me through. thanks very much for your help.
i took a shaping class and shaped a couple of boards successfully, but they were glassed for me – this time i decided to do the entire thing myself, including glassing, finbox, etc.
yesterday i routed out my finboxes (FCS II, with template) and installed the boxes using RR CE epoxy mixed with slow hardener to avoid the exotherm problems i have read about.
I think i did okay, but:
first, when i was routing out the back fin box hold, the stringer exploded and fired shrapnel into the surrounding foam. i “patched” it up a little bit, and the finbox is in, but as you can see there are some gaps there where foam was blown away:
is there anything i need to be doing to correct those slight gaps around the edges? or when i add my “football” patch before glassing the bottom do you think the epoxy will just fill in those gap spaces and make everything magically all right?
when i DO use the FAST hardener for my glassing schedule, will i see any exotherm problems when the fast pools in those gaps? (or don’t worry about it?)
i have a second finbox that settled a bit during the cure – the front side is higher than the other. should i just shrug and go ahead and not worry about this? i’m hoping i can just sand it down and the fin angle will be slightly different than its companion across the board.
for the LIFE of me, i cannot find answer to this question – okay. say you are using the fast hardener. you dump all out on the board. there is too much epoxy and you end up with a full inch (or more) left in your bucket. everything i read says this will “go nuclear” and get freaky hot, etc. my question is, what do you do if you have an inch or two in your bucket? is it dangerous to have that, like will it heat up and begin to smoke? if so, is there any way to stop that? just set it outside on the grass for safety? **i’m assuming there is no safe place to “put” the epoxy, but rather you are committed and have to leave it in the bucket. **thanks for any guidance.
last night i have about a half inch of the slow-cure in the bucket after i was done. i left it (see above) because i didn’t think it was safe to put in trash, so now it is in there hard as a rock with the brush in it. do i essentially have to throw that bucket out now and start over, or is there another way to save that bucket? if so, doesn’t this mean every bucket you use becomes trash as the leftover epoxy hardens (see above)? or do you dump out your epoxy before it hardens? – but if so, how do you do that safely when it’s going to get freaky hot?
otherwise, it actually went okay for my very first time, and i am looking forward to bringing this baby full circle:
Don’t sweat it. The epoxy should fill those in. You could keep a toothpick handy to massage out any bubbles if you want but honestly, I wouldn’t worry about them.
You won’t see exothermic problems there. Again, don’t worry about it.
Maybe you could feather the high side of that finbox to make it flush with the bottom of the board before you put glass over it? The main thing is that you want glass over your boxes. If you have a high side of the box, when you go to sand your board later, you might end up sanding through glass in order to level everything out. That would be bad.
Yes, it will get hot and smoke and melt your bucket a little. You could just set it on a rock or brick or something… Really though, you should not be ending up with that much extra resin. Measure close to what you need. If you come up short, you can always mix up another small batch. You should NEVER end up with a full inch of epoxy in your bucket.
You should have pulled the brush out of it. You might be able to separate the resin from the bucket and use the brush to pull the whole thing out but, if not, just trash it… If you had taken the brush out, you cold be reusing the bucket. This is assuming that you are using a digital scale to measure your resin.
I think you are overestimating this “freaky hot” thing. You can pour the excess resin out if you want. I usually just set the bucket down and let it kick and then, I can reuse the bucket later. If there is too much resin and I am worried that it might melt the bucket, I might pour some out in top of the trash in my trashcan or whatever. It’s really not that big of a deal. The exothermic thing only gets dangerous when you have a large volume of resin.
Where are you glassing? What is your location? How hot is it in your glassing room? Do you have a thermometer?
I glass with poly so take with a grain of salt BUT it can get crazy hot and smoke aswell. I keep a five gallon bucket filled 3/4 with water and dump all my extra resin in that. It goes to the bottom and kick, kills the smell and doesn’t get hot.
Bonus - after a couple dozen boards you got a nice chunk of resin to make art/tailblocks out of.
I’m just a backyarder, no pro here, but this is what I do.
When routing the wood stringer I tend to do the work in progressive shallow cuts, not one full depth cut, because that’s when you get blow outs. Or else use a forstner bit to take out the stringer wood first, before routing, i.e. if I’m drilling for the leash plug with a forstner bit then I might go ahead and use it on the stringer at the fin plug too.
For mixing small amounts, as when setting fin boxes, I use small plastic cups that I keep from yogurt or restaurant salsa. I clean them first obviously. So there is no way I’m gonna have “an inch” of resin left over. More like an inch of resin is how much I mix up in the little cup.
I use thickening agent like cabosil or q cell when I set fin boxes. I don’t mix it peanut butter thick, because I also use fiberglass between the box and the foam, for strength, and to ensure the box doesn’t move around - it’s jammed in with fiberglass around it, not super tight, but enough to hold it in place.
A lot of times I’ll set the fin plugs in two steps, first step with about half the resin needed. Then when I do the final step they are already set in place, and bubbles are far less of an issue. I hate it when I set fin plugs and then when I’m done I find bubbles.
If I did have a cup with enough resin to exotherm and I was concerned about it, I would fill it with a bit of water on top and set it aside, somewhere it couldn’t start a fire, like on a brick or something, but not in my cardboard trash box.
just wanted to say THANKS to all of you for your helpful advice. yesterday i was able to successfully do my first lam with RR epoxy and it went wonderfully. following the “bucket of water” helped me avoid exotherm and otherwise nothing crazy.
now i just have to fix my damn burn-throughs i got sanding this morning…i’ve read that the best fix for this is just to do TWO hotcoat layers. so, some questions:
do i do 2 layers with the recommended amount of epoxy both times, or is the second one a thinner layer with less epoxy?
do FULL sanding workup between each layer? or can i just hit the first layer with 80-grit?
With the brush/epoxy in the bucket, you can absolutely re-use it. When it’s fully cured just squeeze the bucket around the perimeter and it will pop loose the epoxy in one big puck. Push on the bottom of the bucket too to help release the base of the puck. You can even use the brush handle to pull out the puck. On all the other stuff, just go with it. I wouldn’t bother trying to sand level the fin box because it’s likely you’ll hit foam and do more damage. Live and learn…
On your other questions. Go ahead with a second hot coat if you have a bunch of burn-throughs. You don’t need as much resin since you are not filling in weave anymore. Probably 30% less. You should sand the first hot-coat to 80-100 and that’s enough. Get it nice and flat, and take care not to burn through the cloth to the foam. Once the second hot-coat cures, you don’t need to start with 80 or 100 since it’s a thinner, flatter coat. Just start with 150 or even 220 if it’s really clean.
One of the pro shapers in the boardshow competition did what he called a reinforced hotcoat, where he glassed a sacrificial layer of 4 oz. in the hotcoat, then you can hit weave all you want no problem, and it all cleans up on your final coat.
