Besides being told I will burn in hell for all eternity if I build an epoxy board, many people say you have to keep them out of the sun or they will bubble. I have seen such bubbles – not pretty. What causes this and must epoxy boards always be kept out of the sun? Thanks Shine
This has been discussed quite a bit here. The boards you are refering to are built with extruded polystyrene foam (XPS). Epoxy boards built with expanded polystyrene (EPS) or with Clark or Walker urethane foam don’t do this.
Wrong…I have been involved in surfboard repairs for 25 years all surfboards will bubble(inflate with heat) the question here is at what temperature that particular board will bubble or delaminate. Misconception #1 SUN=HEAT No, not always. A hot sunny day at the beach can get up to 120+ degrees F. a sunny day at a different beach can only get up to 60 F. What really damages a board is heat, all surfboards get damage between 145 F. to 180 F. (aprox.) The epoxies will be in the lower scale of that range, and the clark foam (poluirethane foam)boards will be on the upper side of that range. Also it depends if your surfboard has black or dark logos or color airbrush. It’s a matter of habit if you buy a Ferrari you will never park it in the wrong neighborhood. If you own an Epoxy with extruded foam you will not leave the board where it can get too hot, If you can’t do this you will probably never own a Ferari. Remember Sun is not the problem. Avoid boardbags(dark colors),the wrong parking spot,etc. I know some people can’t own this, I mean the Ferrari.
Thanks Greg – that’s what I suspected, the blank was the issue.
Javier…Im not trying say what you are saying is totally wrong but sun is a factor. If there is one tree on the beach where are you going to put your board…Under that tree. Yes a hot car is bad but what is the difference from the sun heating up the air inside of a car as opossed to the sun heating up the air inside of a surfboard. Later http://www.kleinboarddesigns.com
How hot is hot? Clear plastic generally generates 150 BTUs per sq foot of solar heat gain when in direct sunlight (a glass window is about 184 BTUs). So, a typical longboard deck is 14 sq foot. 14 sq’ x 150 BTUs = 2100 BTUs inside your board!! If your board was a house – an approximate recommendation would be 30 BTUs of heat capacity per sq foot. That’s about 420 BTUs to keep the gremlins inside your board warm on a cold winters day. But, a square foot of floor space is also 8’ to 10 foot thick since it goes to your ceiling. Your board is only ~3" thick. Granted, this is an apples and oranges comparison – the sun puts an incredible heatgain inside a board – clearly more heat energy than your home heater creates. So, if you figure your home heater can keep the tempeture in your house as much as 50 degrees warmer then the ambient temperature, the inside of your board could easily have a temperature about 140+ degrees in the sun. That would be hot. Now, which one of your maniacs is going to glass a thermometer into a board to findout for sure. I’m am looking forward to the results on that one. 
Shine
I’m not sure about all these formulas and Ferrari analogies – sorry, but that was pretty bad. Though I do agree, sun does not equal heat – angle of attack from the sun and how much atmosphere the rays have to pass through, cloud strata, all affect how much infrared, ultimately photons, actually hit your board – if your going to bring in formulas then I’m going quantum. This would all affect the absorbed radiation, but let’s not forget our friend convection. Now we need emissivity factors and convective/conductive constants – to sum up my point, this type of analysis is ludicrous. All boards will absorb heat, the darker the more heat. I don’t care if you make your board out of urethane, EPS, or balsa wood – anybody who loves their board will try to keep it out of direct sunlight. Avoid boardbags?… I would rather have a blue board in a blue boardbag than directly absorbing the heat, you will get dissipation and now convection/conduction will be your primary forms of heat transfer. Of course if I had my choice, I’d take a white/foil bag. To end with our bad analogy… would you leave your Ferrari on the curb without a car-cover
Havier is right. All boards can bubble. I’m not trying to make this an issue of this here, but XPS does have more problems with this than EPS or urethane. That is why Havier uses the new method he does to reduce the insidence of the problem. I don’t personally know if this works but I do know that the boards built without this proceedure do have more delam issues. As far as the beach getting to 120, that’s in California. The east coast is significantly higher. The inside of an automobile in Florida in the summer can reach 220 degrees in a matter of minutes. It is actually a crime to leave a dog in your car in Florida. Shine, there is a thermometer on every board. It’s called wax. No matter what kind of board you own, if the wax is melting, it too hot! We have NEVER seen ANY board delaminated from heat that didn’t have melted wax. By the way, great explination on heat relative to surfboards.
Every epoxy board I have ever had eventually bubbled, some sooner than others. And was very aware of the sensitivity to heat. Short of keeping them in a cool meat locker they always bubbled, mostly in the center.
Some people have never surfed with an XTR (Extruded foam core)Surfboard or never drove a ferrari, If you have you will understand. Speed is an addiction and you will do anything to keep that addiction.
The Sun at the beach will get up to 120’F direct Sun Light, inside a Car is like a greenhouse effect it will build heat fast like Greg L. is saying in Florida will get really hot inside a car, over 180’F. easy. If somebody is going to spend more time at the beach in the sand than in the water something is wrong here, now if you don’t have any other options use a white or reflective board bag and leave the bag open. I personally taken boards with Extruded to Ecuador, Cabo San Lucas
Try any of this brands,Dick Brewer,Linden,Blair, Stu Kenson, Midget Smith,Pulse, Al Merrick, Lost, Velzy,etc. By Epoxy Pro they all have the new technology of “Thermovents”, no more bubbles in the middle.
I laminate urethane foam blanks with an epoxy that requires post-curing (baking) at 210-220 degrees F. and routinely do so and have not had any problem with the blanks.The problem with EPS or XPS in my experience is that it becomes softer at higher temp. because it is THERMOPLASTIC - it can be formed by heat.Urethane is a THERMOSET polymer with less dimensional sensitivity to temperature. As epoxy approaches it’s Glass Transition Temperature it becomes softer.Any heavy object or tight rope wrapped around a board glassed with epoxy and left in a hot car, then allowed to cool ,could dent or leave an impression in the board for good !
So, what about these vents that are common in epoxy sailboards? Is that a solution?.. I have one and I rarely release the pressure – albeit, we rarely windsurf in Florida when its really hot. Shine
what are these thermovents? some type of one way valve to release gasses? like a sphincter? where is the valve located?
Again, watch your wax. If it’s melted then you are pushing the envelope no matter what the core is. I’ve seen plenty of urethane boards do the same thing.
The “Thermovents” (Pat. Pending), came after 10 years of nightmares, reason why many people give up the extruded foam alternative. We can install the thermovents anywhere is needed. After you have used your board for a good amount of time (4 months to 3+ years,depends how is the board glassed and how hard you are on boards)the closed cells of the extruded foam will release gas and will be willing to expand with heat, the micro vents will let the gas out when hot and will not allow the water in, a simple solution for a very big prolem for many people. We can’t go in details, we just spend a big amount of time and money in tests with top surfers and it’s really working,it’s great if you like a surfboard that is light and super responsive, and will not suck water. It’s in the water where it matters.