I’ve been having a lot of trouble with bubbles on the rails of skimboards I’ve been making. The decks and bottoms are fine, but the rails bubble a lot. It does not happen right away. Everything looks great for quite a long time, then as it cures the bubbles show up. They are just on the rails. I have tried wiping down the boards with denatured alcohol between coats. This got rid of the fish eye, but not the bubbles. Does anyone have a solution to this? Does using pigment or sanding the boards have any impact?
Bubbles are air, watch the temperature, don’t glass as it’s getting hotter, you want the board to be breathing in not out, glass as the temp drops, I think that’s what it could be.
I don’t think pigment would be a factor as long as it’s not over pigmented. - I’m guessing that the resin would stay rubbery or something and never harden all the way.
Another reason for you problem could be that the fiberglass cloth doesn’t like making sharp corners. It eventually tries to round off a hard edge by lifting up right by the edge. If that makes any sense. The lighter weight the cloth is the tighter it will wrap - like on rail edges and thin nose and tail ends, and in your case, a thin skimboard rail. I don’t know of an easy work-around if this is the case, outside of vacum bagging? Just sand your laps down to expose the bubbles then come back and drop a little resin on each bubble spot, then finish sanding the laps. Hopefully it’s the temperature issue Hicksy is talking about.
You could also try using a longer lap so there is more lap area to help hold the cloth down tighter.
I’ll try working with the temperature, but most of the time I’ve been doing this during the evening when the temp is constant or dropping. However, it has been very hot in my garage – ah, shaping/glassing bay:) – about 90 to 100+ degrees. Will that effect it? Regarding the laps, oddly enough the hard edge corners are good. I’m getting the bubbles in the rounder/softer sections of the rail.
I’ll try to post some picks after I get back from vacation.
Thanks again for all your help and advise.
BTW just glassed another skimboard last night and tried to get the laps wetter. I’m going to fill coat it tonight and I’ll let you know if that helps.
I know what you’re talking about! I just lammed a board recently with epoxy in the sun then I decided to take it indoors to where it was cooler. Then the next day I saw that it had developed big bubbles in the stringer area and where I had done some posca art. I asked Greg Loehr in Cerritos about this because I was quite sure it wasn’t due to gassing because I took it from warmer to cooler temps. He said that it might be from the bubbles in the resin that I had not been able to get rid of. They seem to pool together and create one big bubble. I think he was right because I wasn’t quite experienced with working with epoxy and in retrospect, I did over mix it and had alot of bubbles. I saw him lam that board in cerritos and man was he pulling of resin really hard. I didn’t pull as hard as he did. I think I should pull harder next time and mix slower.
Rio
edit: I see you’re in sunnyvale. I moved back to my parents’ place in los altos so we’re a stone’s throw away from each other. If you wanna shape together sometime just gimme a PM I’ve got some left over cloth and RR resin.
If your pre-glass job has been sitting in this “shaping bay” ;D all day and you glass it as the day’s cooling off it should be at it’s peak temperature. That means it’ll be cooling off as it gets glassed. So the foam/wood will be “breathing in” – so it should “inhale” some resin, rather than breathing air bubbles into the resin. Hope you don’t have a big-ass heater running that’ll warm it up more Are your rails wood? Wood breathes faster than foam!
You know, I had some bubbles in my hotcoat using RR & appropriate additive “F” too. I think I have figured out what happened. My first try (the one with all the bubbles) was done in my basement in falling temps (heated up my work room & the blank to eliminate eps outgassing). The resin/hardener was sitting in approx. 75 degree temps & seemed “thick” when I was stirring it. I stirred the crap out of it and, in addition to completely mixing the resin & hardener, must have “whipped” in a lot of air…
Second side: same stuff BUT it was mixed more gently, in my garage in 90+ degree heat → came out great.
So, in my case… operator error & not paying more attention to the posts that mentioned warming up the resin in cooler temps.
heh I am pretty sure that epoxy being whipped like cream, while it’s thickening, will hold air bubbles We used to do it on purpose to each other in high-school tech classes
I just finished my first skim board and here is how I treated the edges.
I hope this line drawing works. Its a bit simplistic. I don’t have pictures of this process.
I wrap the edges with a product called Dynel that I cut into strips the thinkness of the board. Then wet out the each strip a attach it to the edge building up layers. 8 on this board.
Thats about 3/16 of the inch. I do this to the finished shape before I glass.
I use clear packing tape as a poor man vacum bag to hold the stuff in place. It works the air out nicely. Do ~half the board at a time.
Its really rough at this point. After it cures I grind it flush with the bottom and shape the top.
Then glass the board out over the dynel. At that point I don’t have to wrap the edge. Its already sealed and very tough. Dynel soaks up a bunch of resin and is very abrassion resistant when it is cured. I use it for edging on kayak paddles. It stands up to abuse from the river rock very well, and makes a nice way to seal a sharp edge without having to try and wrap it with glass.
This should hold up to anything you could put it through.
Are your rails wood? Wood breathes faster than foam!
We used to do it on purpose to each other in high-school tech classes 