I’m a backyard (more like garage) shaper and have built a handful of boards. Just recenlty, I ventured out from making boards for just myself and built one for a buddy. Basically charging them cost + some booze. I figure it’s a good learning experience and my buddies know what to expect. I just fininshed another board for my second “customer.” I used epoxy resin on a US poly blank. I painted the blank grey and blue. Took my time glassing, hot coat, sanding, all the steps. Met my buddy down at San Onofre this weekend to deliver the board. Surfed for about an hour and half then took a break on the beach. He put the board in the back of his truck and threw a board sock over it to keep the sun off. I took off (plans with the family). The last week + has been very warm (probably low 80s on the beach) and lots of sun. My buddy took the board out for another session and noticed some bubbles on the bottom of the board (the side facing up towards the sun) on the grey part of the board. Didn’t realize epoxy was this sensitive to heat. So frustrated. I understand (or hope) that this is just the nature of epoxy but can’t stop thinking…maybe I messed something up during the board build. Even though these are my friends, I don’t want them to think poor quality / craftmanship. Maybe its’ more frustrating since they are friends. Anything I can do to prevent this in the future, other than warning the customer about epoxy and heat?
Dark colors plus sun equals a delam. Pretty simple.
It is not caused by using epoxy, but by a bad lam job.
The board probably already had bubbles under the lam, they just expanded by the heat.
You should watch some videos on how to laminate using epoxy, there are some differences with laminating polyester.
Get the lam on tight. You want to hear the weave of the glass when you squeegee the excess epoxy off. Like all boards, when not in the water, try to keep it out of the sun.
Also, your paint could be a possible culprit. I let a friend of mine build a board in my shop since he helped me move to a new location and gives me a hand from time to time cutting blanks. Anyway, the guy was way more concerned with the paint job he was going to put on the board than the actual shape or construction of the board. I personally use heavy glass and apply it in a vac bag ensuring a tight bond between foam, resin, and cloth. Well, my friend’s purple and neon paint job would have become blurry under thick glass, so he insisted on using several layers of thinner glass. we took the board to Acapulco this winter and he left it out on the beach for hours at a time and amazingly enough, there didn’t seem to be any issues. When we got back, he proceeded to leave the board in a black Chevy Blazer and the whole deck delaminated, one giant bubble, that shrinks when it cools down. I’ve hand laid boards with the same cloth he used and never had an issue, but I do all my color work with pigments and not paint. So I’m guessing the epoxy wasn’t able to penetrate the foam and create the mechanical bond needed to deal with the high temps caused by the darker colors. I love to help friends out and to see more board builders, but this thing is so damn ugly that i was embarassed that it came outta my shop and I want it to disappear. Of course we could inject some resin and throw it in the vac bag to pull it down, but with a board this heinous, I told him it would be best to retire it and bury it deep in a closet or even better, underground…
Paint on a poly blank + epoxy can cause many issues if the paint isn’t dried, applied too heavy (seems dry but isn’t), or just the wrong paint type; same guidelines as glassing poly over paint. Another possibility is a soft blank (or over shaped deck) that would’ve done the same even with poly resin. This is a mechanical bond problem and the delam happens just like on a poly resin board when the glass separates from the foam and the air underneath and expands when heated. Lighter deck glass didn’t help either. It didn’t happen right away since successive deck compression was needed to get the failure started. If it’s hot enough, a very small separated area can expand to very big one in no time. Air expands at a tremendous rate, and when the peeling process on bond gets started, the expansion is exponential if heating is constant. No point in fixing it, it’s either the paint or the blank and will happen again. But tear off the deck and look for major dents so you’ll know if it was a soft blank or the paint. Best to learn at least something from all of that.
Seconding what Hof said, epoxy and dark colours are a bad mix without an elevated temperature post cure. The temperature at which the laminate wont react mechanical loads properly is called the Thermal Glass Transition Temperature (Tg for short). For a room temperature cured epoxy this is probably somewhere in thre region of 60 degrees C. Coloured white in direct sun, the board should never get there, but dark colours will.
We had 2 things leave the paint shop without the tech office knowing what colour they were. One was a hovercraft engine cover that proceeded to warp in the Yorkshire sun and the other was an aircraft wing, that we quickly got back inside and re-painted! Thats the reason virtually all composite aircraft are white. There are two exceptions: 1) they are using medium cure temp pre-pregs or 2) have a death wish.
I just did a full carbon board and I’m thinking of adding a breather plug. Thankfully there is a decent sandbar in front of my house because if I even take the time to do a quick stretch before surfing, the wax starts to melt… I also made a few carbon handplanes from some leftover material. I accidentally left one in the window of my RV and the thing formed a smaller delam spot, but it was cooking. I used 2lb eps foam and vac bagged the carbon on. On the plus side, I guess I’m finally getting water tight laminations!
I’ve seen Surftechs bubble when left in the Sun too long. Not all were dark colored, either.
I had this happen with an epoxy board.
But it was a hws, painted…over a bad layer of uncured poly resin sealer, then left in the hot sun…with the vent plug in - I guess you could say I was asking for it, LOL