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…hello man, seems that you and others misunderstood my previous comment;
dry or not dry will be not fully cured until 12 hours.
Cure times are one thing a bit different than tackiness.
I put an example: if you do a gloss coat with MKEP the coat will be hard, seems ok to sand, etc but the reality is that is not fully cured for several days; depends on the weather, etc.
Im not guessing here
What Reverb is saying is that resin is liquid plastic that CURES not dries. Whether you use catalyst, UV resin, or a combo of both, the resin still needs time to reach a FULL cure.
It’s easy to figure it must be totally cured i you can flip it and go to the next stage, or even sand it.
Not so.
The manufacturer of the UV resin can give you that information if you request it. They do tests to determine maximum cure under specific condiitons.
Your individual cure time will vary with the previously stated choice of how to apply it as well as the method you might prescribe to suggested by others that have posted here.
Then, on top of that, you have the amount of UV rays on that particular day, humidty, and temperature. And beyond that you could even take into consideration how heavy a concentration (how wet) your laminate is with whatever weight ounce cloth; 2, 4, 6, 8, 10?
Don’t you think the UV rays would penetrate a 2 oz layer easier and quicker than 10 oz volan? Or multiple layers?
A lot of experienced laminators choose to add .5% or other small amount of catalyst to their laminates and/or hotcoats. Some guys don’t believe you can obtain a 100% cure using UV resin without any catalyst. Others believe sanding a hotcoat that catalyst has been added is more toxic than without. Don’t forget the catalyst comes in different strengths as well.
Lotsa variables abound!
It would be great if a U.V. resin manufacturer would clarify some of the misconceptions about curing of this incredibly convenient product.
Reverb may well be right about the 12 hours needed, but I’m not sure how he arrived upon his curing schedule?
In my case it doesn’t help me much, as (frequently) the clear boards I do are done in 6 hours start to finish anyway… and there are plenty of them that got surfed immediately and are still in great condition.
Hey reverb & deadshaper - thanks for explaining that there’s a difference between “it feels cured” and “it’s really cured.”
One question: what is the practical difference between the two? In my experience, it has been fine to grind laps, sand hotcoat, etc., when it “feels cured.” Should I change my process to give more time between stages to ensure that it’s “really cured”?
Or would you recommend just glassing/sanding the board quickly as usual but then making sure that it isn’t surfed for a few weeks to ensure that it’s sufficiently strong?
Thanks a million - really appreciate all your thoughts and advice here.
Full cure is what you want for riding a board. You don't have to wait for full cure to ride 'em, but it seems to help. I've ridden plenty of boards "too soon" and they've held up well. . I don't think you need two weeks before riding, more like a day as Reverb said.
Sounds like you've got it figured on grinding laps and such. As for when it's best to sand, it's pretty easy to figure out. Typically, on a sunny day, leave the board (once the wax has risen) in the sun for about 5-8 minutes and it'll be ready to sand. When it's kicked, the board will feel slippery and the surface hard. To make sure, take a piece of sand paper and scuff it, if the resin grabs and the paper gums up, give it a bit more time. When I sand, I'll take the board inside and let it sit a little while, maybe 15-20 minutes, then sand it. One thing about it, if you do it sooner, it's been my experience that it sands like butter. If you let it sit around a few days, they get rock hard and can be a bit tougher to sand.
To answer you directly, sufficient cure time for handling might vary from 10 minutes to half an hour or more IF you are glassing toward the end of the day or with a lot of cloud cover. UV that is cured in the sun, as a general rule, you should at least be able to see shadows for quicker curing.
That doesn’t mean you can’t kick the resin off. I tried a test once but applying it on a repair, then put wax paper over that, and put it out in the rain on a rack… it still kicked fine after 15 minutes!
If you ever mix your own UV powder into resins, you can customize the sensitivity to light that it will kick. This is tricky though and if you add too much it can get super hot when curing, and even end up yellowish. The powder in the resin looks like little reflecting mirrors like a hologram or something. Maybe that is the original concept that makes it work, by reflecting the sun’s rays thoroughly thru the resin thereby causing heat in place of the chemical catalyst. Whatever it is, it’s damn good science.
I always stir my UV resin even if I am not adding any catalyst. If those ‘little mirrors’ are actually what makes UV resin work, I’d rather be sure the ‘colloidal solution’ is suspended thoroughly, and that there hasn’t been any settling or some other unforseen factor that might affect the job.
As far as the comment about getting a drier job by using a box w/o oxygen or whatever… who the hell wants to deal with crap like that? There’s not enough profit to warrant such projects, and I don’t use a light box because I would rather kick the resin quickly without excessive fumes and boiling off into the atmosphere. I actually have a door adjacent to the glassing rack that I can adjust the amount of UV entering so my laps will start to stiffen a little bit (like properly time catalyst glassing) right before I lap the rails.
Above all else, have fun, wear gloves/mask. Use a good barrier cream and a minimum of acetone to clean tools.
Like I said, I never tried it. I was just repeating what my vendor told me. He was actually talking about how to get the most out of a vinylester, too; not a polyester. Bone dry sandable finish with no surfacing agent or thinner.
I could see starving the resin of oxygen by vacuum bagging a wet lam (transparent bag) but I’m sure you’d need a great filter in line with your vaccum pump or it would fry itself in no time flat.
Question for you guys who have mixed the uv powder into your resign. This I tried, when I glass the board, and then took it out to cure, I left it in the sun for 5 minutes or so. I used no catalyst at all, it wasnt overcast... The board was sorta tacky but hard, I brought it back in and sanded the laps then did the other side, again the board was a bit tacky but hard as well, cant really explain it well.
All I know is im keen to buy the premixed stuff (im not sold on mixing it with powder), stir it and let it sit for a while before using. Could anyone explain who has used the powder why I may of got this tackiness, I thought it was meant to set hard without and tack. Cant explain myself well but hopefully someone knows out there.
Howzit di99er, I am just now reading this thread so haven't read what has been written before but it sounds like you may not be using enough powder or not mixing it good enough. When I used to mix my 5 gal tubs I would roll them around the yard for at least 10 minutes and then shake it for another 5 mins and never even noticed any difference than the premixed stuff from F.H. That's about all I can tell you. Aloha,Kokua
OTIS. Depending on what area you are in You can try Bashams in San Clemente or ProGlass in Costa Mesa. Pro-Glass is on Placentia and 18th right by crystaliner. IMO the only thing crystaliner is good for is tints, they have a great supply, everything else they are on the high end pricewise. Pro Glass is much better price wise and Pure Glass is the best. Im in HB and I hit bashams like once a week. Pro-Glass in between if I need something fast
Thanks RogueS,
PureGlass is the name, you use Pro-Glass alot probably a misspelling.
Interested on your opinons on this>
Speaking to an old mate who backyards his own rides about glassing etc, he tells me a tip from a pro doing 4 ounce top and bottom on shorties for himself is to leave the board in the LAM stage ( top and bottom ) wrap in plastic or whatever so it does not get crap in it and store for about a week before hot/filler coat …
Think im going to give it a go (mekp + UV ), makes sense to let the lam ’ gas off ’ before sealing it , guess i want to loose wrap the board so it can breathe while curing …
thoughts?
Sounds unnecessary to me.
Completly unecessary and a waste of time.
Hello,
Over the years I have held on to the theory that letting a board set/sit for a few days after lam stage resulted in a lighter and stronger board.
However, I never put it into the production line.
The reason behind me believing in this is about 8 years ago I used to sponsor the WQS surfer Jock Barnes, Once I left a few of his boards in lam stage (purely due to the fact that his schedule had changed and I just went on to other work until he picked them up). It turned out (he says) that they were more lively and responsive and also lighter then previous boards (could have been coincidence). Jock insisted that we do this with all his boards, we tried to with most but as time went on and over a hundred boards later a few went through with the normal glassing schedule. He swears he noticed the difference. But there are so many variables that make up a board that this to could have been superstition??
I too have surfed many boards left in the lam stage for a few days (even up to a year ha ha, you know new project comes to mind before previous is finished) and I do feel the difference… I think! ?
It does make a bit of sense, to me.
How much styrene evaporates out of resin? I herd %30 (but that seems very excessive) I don’t believe this to be true, But maybe?
only a few comments? … it sure can’t make the glass job weaker by waiting a little in lam stage …
the reason i posted other than what the ol mate in the water told me was >
a board i recently finished with a heavy ( 6 oz biaxial + 4oz deck , 6 bottom- resin gloss finish glass schedule ), put my weight about 400 grams heavier than what ive been finishing boards of same dims … and rode it 2 days after lam (pigment(lam) +mekp+uv), pulling it out of board cover (after 2nd surf - only in cover on way 2 and from surf ) and could smell that poly still gassing !!!
maybe im wrong but the hot/filler coat would surely only lock in unfinished reactions in the lam if too early…
from the spraying of auto primers/2k base coat /clear finishes ive toyed with >>>>when it smells it’s still alive!! …
ie you lock down a basecoat with clear too early and problems will pop up later
figured the same with poly
anyway ill give it a go…
interested in hearing the result mate, my boys board has been sitting in stands now for about 2 months it feels like waiting on hotcoat, will wash board down before I do it.
just a mental excercise:
probably one of three things happening here.
-
gas offshoots , I think unlikely
-
unfinished reactions, I think unlikely
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hot coat not bonding as well to the lam at a microscopic level, seems like a good explanation, as this will allow for more flex.
Perhaps a bit of dust, grime and time will get you more flex.
The same goes with Blanks. the older they get the lighter they become stronger they get the truer they are and the easier they are to shape.
I know this as fact.
It makes sense to me to let a board sit after each process.
Oh and No its go nothing to do with bloody dust dirt grime dog shit or and other crap you might have in your work space.
To say a board doesn’t keep letting off gasses is complete shit…If you ask me! so why would glassing it quickly NOT lock some of those liquid-gasses in.
I’ve done a lot of boards this year in UV and they are heavier then those left to sit done with only MEKP, even if it were for 48 hours.
hmmm, lets look at some facts:
http://www.physlink.com/education/askexperts/ae650.cfm
1 cubic foot of air at standard temperature and pressure assuming average composition weighs approximately 0.0807 lbs.
A typical shortboard 6’ something" is bounded by about 1.5 cu ft of volume.
If you were to crush a 6er foam blank down to nothing and throw out the powder, the weight of 1.5 cu ft of air would be
1.5 * (.0807) *(16oz/1lb) = 1.9368 oz.
The toxic fumes escaping both the foam and resin are probably lighter than air,an assumption, else their ultimate escape from a laminate bonding would have to be masterfully planned. So it would seem that indeed if a maximum amt. of gas were to escape both the laminate and foam then indeed a board could be something on the order of 2 oz. lighter.
If indeed you are getting more flexible boards after letting a laminated board sit, which I do not doubt, I still think its due to # 3 above still, due to less bonding between the laminate and sanding coats etc. Whether that is due to time, dust or grime or a less bondable surface(offgassing, curing and time may explain), I would still lean towards weaker bonds between layers as a good way of thinking about it and/or a further method of achieving flex.