Submitted by Terminal on Tue, 07/14/2020 - 03:36
Anyone know the max temperature that is safe for both epoxy and pu boards? Min temps not really an issue unless you're Torren Martyn I suppose. Seems hard to find any real guidelines anywhere...
Thanks in advance
Maybe it's already been discussed on here, so link to the thread would be great too. Thanks!
Good question. In summer, my shed gets a roast on and it has me wondering too.
I think someone made a video on EPS vs PU in a hot car.
Anyway, keep EPS out of the heat and dark painted/tinted boards also.
I used to leave some of mine in Indo every 2 months until it started to ruin them, the cases I stored them in went mouldy!
I keep boards over in Indo one year i took over a few almost new very white EPS/Epoxy boards, next year i went over and opened my board bags and they were like 20 year old yellow boards, was pretty depressing. (im talking true yellow not a little yellowed)
Also had one PU/PE in their to from memory its still went yellow but nothing like the EPS/Epoxys.
Apart from the yellowing otherwise boards seem fine.
Funny thing is for years earlier id had EPS/epoxy and PU/PE boards there and they had barely yellowed.
They were all stored in the rafters but must have been stored in a different area or something where the heat was really radiating...who knows...anyway they are yellow now. (although i brought one home and gave it a full re spray)
Hi ID, your experience with random yellowing is, I find worthy of further investigation as it is a really common and major issue for so many surfers.
There would appear that there is some scientific/materials based issues at work.
As a fan of Dr Karl his approach to such conundrums usually involve fact finding in an effort to build a foundation that may identify a cause toward possible solution.
Can you tell us if the boards were from different manufacturers (avoid naming brands..keep it scientific) and from the range of ages.
My understanding is that boards are basically petro chemical based plastics and most plastics suffer damage from heat and UV.
The very fact that resins require a catalyst that usually generates various degrees of heat to cure provides a link when one considers what happens when too much catalyst is used results in a hot mix that goes yellow/brown and shrinks and cracks.
So could the boards that yellow more readily been subject to different concentrations of catalyst when glassed?
@indo, yeah same thing for me with the yellowing epoxy. It was manufactured in 2014 and yellowed rapidly last year after going into a storage shed for 3 mths while wife and I were os. I had 7 boards in storage and the pu's yellowed too, but only slightly. No idea what sort of max temps were reached but one board was waxed with orange/yellow label sexwax, it was clear it had softened substantially but never actually liquefied and ran.
As per lj, the epoxy is a reputable brand and made in Aus.
As an aside I have a late 70s Hot Roc single that has barely yellowed at all relative to my modern boards.
Hey terminal I also have many 20, 30 and a few 40 year old boards from several different manufacturers, a few of which made in USA.
None are badly yellowed as ID described. Some as clear as they where, and they are also in perfect condition without dings, compression of crazing.
So one theory I submit is that they were made by guys I know were really known for premium quality relative to blanks, shaping, glassing sanding and finishing.
The glassing and sanding was done by craftsmen and boards left to cure for a week or more before surfing them. Pretty sure careful consideration to temp and humidity on day the resin was mixed and boards glassed. Boosting catalyst for quick production was considered a no no.
Also back in the day we fixed dings immediately to prevent water ingress into blank.
Blanks are they other side of the equation adding to the variables that opens up pandoras box.
So, is it the resin or blank or combo that is yellowing.
I believe that many resin suppliers tinted their resins slightly blue (even colouring the drums light blue) in an attempt to thwart concerns about the natural slight brown colour of resin.
In regard to yellowing PU/PE boards and EPS boards are two totally different things.
PU/PE boards although the resin might yellow a bit i believe it's more the foam that mostly yellows, if they are kept out of sunlight or the foam sprayed white they will stay pretty white, i saw a board that maybe had never been ridden from late 80s the other day and it was still close to new in colour.
While with epoxy boards its the actual epoxy resin that yellows over time my epoxy boards even in Australia yellow over time, i always thought it was from exposure to UV light. (where the wax is normally stays white)
However what happened to these boards was next level like they almost looked like sprayed yellow boards and bottom and top were affected and they were in thick board bags all sealed up, so i expect it was heat and not UV that made them yellow.
But we aren't just talking one day of heat, we are talking almost a year of possible crazy heat, but the interesting thing is id left the same brand boards in a similar area other years didnt yellow noticeably from season to season.
I don't think it matters in naming brands, two were Firewires and another was an older Chilli Fiberflex, both just as bad as each other but the Chilli was already a bit yellow.
Only epoxy boards that i know of that wont yellow are those crappy surf tech ones but they must put something in the resin as the resin itself is like it's white.
There is suppose to be non yellowing clear epoxy resins but from what read they still yellow over time if exposed to UV light, you get the same issue in other applications of clear epoxy resins like concrete floors, you ca often see a yellowing around exposed windows/doors while darker areas of rooms floors stay clear.
Interesting stuff ID that the yellowing appearance of boards most likely is the result of the materials we use with universal to change how we use them.
Many industries use epoxy in manufacture. Boats for instance don't have the yellowing issues because they must use white based or colour added pigments.
I assume that is what Surf Tech and others also use yet we tend to frown upon that as for some traditional reason we want to see the foam/blank/stringer otherwise it is not "a real surfboard".
You yourself said.... Only epoxy boards that i know of that wont yellow are those crappy surf tech ones but they must put something in the resin as the resin itself is like it's white.
Time to pull our head out of the sand?
Reminds me of a joke that came to me the other day... A guy orders a new board from his local shaper. The shaper excitedly informs him that they are now using a new hi-tech non-yellowing resin. “What colour would you like your board anyway?” “Yellow.”
My wife threatened to divorce me when I sprung that one on her. Anyway, It is well known that polyester/PU surfboards gradually yellow with exposure to UV sunlight. It’s news to me though that epoxy/EPS boards can go yellow with heat. Mine seem entirely unaffected. Mind you I live somewhere that doesn’t get very hot and I’m always careful to store my boards somewhere cool in the shade. I get the feeling that your boards were really baking I.D. Or perhaps there is another unknown factor at play. It would be interesting to hear from someone with some expertise in this topic.
Same goes for oil based paints, polyurethane varnish and timber floor coatings, will all yellow over time, acrylics (water based) and epoxy dont (or do so much less anyhow) and will stay clear longer are a bit more flexible but they are not as tough / hard a finish as the oils
Oil based paint's are even weirder you would expect they go yellow because of UV light but its actually the opposite, they go yellow from lack of exposure to light, for instance if you have oil based skirting boards or doors etc in a white colour go have a look in your cupboard the paint in there will be more yellow than the exposed side of the door and general room.
You can see the effect even more if you have something screwed over oil based white paint and you take it off it will be really yellow underneath.
And it gets crazier you can actually reverse the yellowing effect to an extent by exposing the oil based painted areas to light, say you have a holiday home and always close all the curtains up when not there, if you leave them open instead after a few weeks or months the paint will whiten up a little...weird stuff.
If you think I'm spinning BS google it.
Now that you mention it I think you’re right on this one. No need to google. The amazing world of material science never fails to surprise.
Interesting obs from all. Agree with spuddups, expert opinion would be great. It's really interesting that there's not really any guidelines anyone has come across, particularly given the financial and emotional investment some of us place in our boards. My best board will be buried with me, if it makes the trip...
A lot of the LFT Firewires I have seen begin to yellow in the shop. Surely they are a big enough company that they can prevent this?
My JS Hyfi is still bright white at 4 months old. Heavy use but always bagged when not in use. Do they spray the blank white? Wonder how long the bright white will last?
I think some of the new blanks actually have a blue tint which somehow “brightens” the white.
it's the epoxy resin which yellows though.
I didn’t even realise this is a problem till this topic popped up. I’ve been making EPS/Epoxy boards for a few years now. I just use standard white polystyrene and epoxy resin. I don’t seal the blanks with anything, just glass straight on. My boards are all still white as. My PU/Polyester boards look brown as compared to them. My only thought for why an Epoxy/EPS board would go yellow is that they might be adding something to the resin to speed up the cure. Or maybe it’s the shit they’re sealing the blanks with. Once again, it’d be good to hear from someone who knows the score. Reckon I’ll put a topic up on Swaylocks and see what they have to say. Will report back.
I have a second hand sci fi and it is yellow compared to a brand newy still goes well but.
Thanks spuddups, maybe someone over there might know something about it. I suppose the cosmetic factor is secondary to actual damage to the board (delams, potential degradation of the resin, blank damage etc.). In terms of the yellowing, is that indicative of the integrity of the resin deteriorating? Etc.
Hey felluhs, I posted a topic up on Swaylocks. A couple of enlightening posts by knowledgeable people followed. I’ll copy and paste them for you below. Also here’s the link for the actual topic. https://www.swaylocks.com/node/109098
Last seen: 3 days 4 hours ago
Any board spray finished with an automotive clear coat will yellow. So that would be Surftech, Boardworks, NSP etc. More noticeable on white or clear boards. Less so on colored or boards painted various colors. To see an example, just take a look at any white Boardworks or Bonga Perkins model that is more than a year or two old. If you sand off the clear coat; the bright white paint will be revealed.
Last seen: 1 week 1 day ago
It is just due to the resins that are used.
Surfboard epoxy resin has typically been UV stabilized because it's almost never coated with an opaque paint.
The factories in thailand typically use non-stabilized resins because they have been painting them for ages, if they now suddenly stop doing that and keep using the same resins, you get a lot of yellowing.
In the past I had quite some yellowing too, because my composites store did not sell stabilized resin. But now with the epoxy river table hype, they caught up and have quite nice and stable resins, also for laminating. Since then, never had any yellowing anymore (a UV blocking varnish also helps).
It's just a resin formulation thing, standard epoxy resins typically yellow very fast.
You'd think Firewire would have used UV stabilised resin. They seem to yellow really quickly.
Hmm some of the comments don't make sense to me.
All the surf tech boards i have seen have stayed real white, I don't recall seeing a yellow one.
I know FW have swapped the resins they have used over the years too from standard type expoxy's to plant based resins to get all those eco ticks.
But in all honesty in my experience all the FW's ive had they all seem to yellow but some worse than others the older ones maybe more so though.
If you were making boards with an epoxy that doesnt yellow, you would want to stick with it though, ive seen a few test where they compare different ones and how they yellow and even a lot of the ones that are suppose to have UV blockers still yellow
Website link to test (obviously used for art purposes but still same deal)https://polymerclayjourney.com/2019/01/16/resin-yellowing-test/
Plus another test with video
BTW. was reading more about it, and apparently yellowing is caused by two things UV but also excessive heat like what must have happened to mine i had in Indo, mine still seem fine but what i read is also breaks down the resin or something. (it didn't sound good what i read)
I agree, all the ST's I've seen have stayed white.
and the NSP"s and BIC;'s.
BTW. was just looking on FW website seems they use one of the brands tested that actually done pretty good in that video test the "Entropy super sap" but FW website list it as "Entropy bio resin" not sure if exactly the same or just same brand.
well done ID but it raises ben more questions..
it seems "resins ain't resins, Sol" so could the best performer used mainly for casting be used to glass a board?
Interesting to know the differential in cost, shelf life and I suspect every mixture was done using scales for mixing and taking temperature and humidity into account in an controlled environment for an accuracy, something that I wonder how many in our game do?