Just had a thought as I went to the garage to think about glassing the board. Seeing as I’ve boarded up the window, and sealed around the door, and flourescent tubes give off small amounts of UV light, how the hell am I supposed to see what I’m doing in the morning when I start glassing?
No, just kidding, but really, is there a preferable lighting type for glassing when you’re using UV cat in the resin? Not sure that candles are the way to go with the big FLAMABLE label on the resin can.
Will ordinary filament bulbs be OK, or am I safe with the flourescent tube light?
I glass UV in a tiny room under the same fluorescent lights that I shape & sand with, no problem. I just slide my glassing rack right onto the posts for the shaping rack.
I always add a small amount of cat to my batches to keep drops/spills that miss the drip tray from staying sticky on the floor.
I have no experience with UV catalyzed resin, so I don’t know the answer.
However, since the energy of electromagnetic radiation (i.e. light) decreases with decreasing frequency, I would expect that the reaction rate will slow down with decreasing frequency of the illumination light (indeed, the reaction might not even occur if the wavelength is long enough). If the rate at which the resin kicks-off decreases more rapidly than the intensity of the illumination that you can observe (i.e. in the visible range), then there is the possibility that by lowering the frequency of the radiation you may be able to slow down the reaction to yield the working time you desire before you completely lose the ability to see what you’re doing.
If this hypothesis is correct, then one would expect the times of exposure required to kick-off the resin to increase in the following order (i.e. from quickest to slowest kick-off) while still being able to see adequately:
(white) fluorescent > “warm” fluorescent > incandescent > “extended life” incandescent > “extended life” incandescent operated at a reduced voltage > red-filtered incandescent (e.g. as used in a photographic darkroom)
So Bud, the flourescent lights set the resin, or you're saying you work under them and then take it out to sunlight?
yeah, I carry the board into the sunlight to cure. Sorry I should have said that the fluorescent lights don’t seem to have any effect in the time that I’m working with the resin. I watch the clock even though it’s UV, I’m still slow but getting better/faster. I think I’m around 15 minutes to lam a shortboard bottom
Not sure if at some point it would start to gel because of the lights, but I don;t think you want resin sitting around on the foam for very long anyway.
obviously I’m just a backyarder so take my input for what it’s worth
I’m not sure if anyone has tried one of those energy saving bulbs, (the ones that look like a corkscrew) but I had one and it set of my resin within about two minutes. There was no MEKP in there either.
Interesting guess, but I think you are off the mark. The reaction is driven by chemical potential, not the energy of the photons hitting the resin and heating it up. The UV catalyst is sensitive to a relatively narrow frequency band in the UV band. When hit with UV it cracks and starts cross-linking the polymer. There is some sensitivity to the time/intensity required because all of the photo-initiators need to get activated and there is some randomness involved
There is certainly some change in sensitivity to the frequency of UV, but on a scale not controllable in most surfboard factories. In the semiconductor fabrication world, there are lots of such materials utilized and photo-lithography often uses very narrow frequency ranges to improve repeatability. I doubt there is a i-line stepper used to cure boards, but if there is, I would love to see it.
On a related note, the semi-conductor world has some great UV-epoxies. Unfortunately they are prohibitively expensive for board building.
Interesting guess, but I think you are off the mark. The reaction is driven by chemical potential, not the energy of the photons hitting the resin and heating it up. The UV catalyst is sensitive to a relatively narrow frequency band in the UV band. When hit with UV it cracks and starts cross-linking the polymer. There is some sensitivity to the time/intensity required because all of the photo-initiators need to get activated and there is some randomness involved
There is certainly some change in sensitivity to the frequency of UV, but on a scale not controllable in most surfboard factories. In the semiconductor fabrication world, there are lots of such materials utilized and photo-lithography often uses very narrow frequency ranges to improve repeatability. I doubt there is a i-line stepper used to cure boards, but if there is, I would love to see it.
On a related note, the semi-conductor world has some great UV-epoxies. Unfortunately they are prohibitively expensive for board building.
Thanks for the information. Please note that my hypothesis was not based on the heat developed–otherwise the order of the various illumination sources would have been reversed (for equal power consumed by each light source)–but rather by the activation energy required to trigger the catalytic reaction. If the catalyst is sensitive to a narrow band of frequencies, that is the result of the UV frequency being resonant with some vibrational state of the catalyst (the inverse of the generation of the yellow spectral line generated by heating sodium) rather than simply providing enough energy to excite some state (like the photoelectric effect).
I would imagine that in photo-lithography an extremely narrow band of frequencies is desirable as it avoids the distortion associated with changes in the index of refraction (of the lens system) due to the range of frequency present in the source.
A related question: Does the UV resin method stink up your garage? One of the reasons I’ve never tried to glass (except small dings) is that I’ve heard you can never get the PE resin smell out of your garage, or even your house (my garage is attached). But I thought I read where it is the hardener that really smells and with UV you don’t get that. I sure would like to try my hand at glassing and not pay for a shop to do it, even though they do a beautiful job.
i have always glassed using UV resin under florecent lights and had no problem with the resin gelling, i can take all the time i want.
when i first started glassing it was in my garage which the rest of my 100 year old house is built on. with the lack of sub-flooring, the whole house would smell after i glassed but if i opened all the windows and turned on fans then it would be ok after a few hours- well, more like 6 hrs. but the smell will go away.
I buy UV catalyst from Mitch’s Surf shop in Solana Beach Ca. I mix that with lam resin that I also buy from Mitch’s. (poly)
In my garage with several florescent lights and with the door open aprox 14 inches I have never had the resin go off…I can do a lam coat in less than 20 min but in the past I’ve taken over 40 min without the resin going off.
Still worried? With repairs jobs up to 12 inches by 12 inches I keep the garage door open. Never had a problem. Take it out side into the sun an everything kicks off fine…
Poly smells…the quicker it cures the quicker the smell goes away…I still do my hot coats with MEKP…
Here’s a little hint for the garage builders.
After I lay up a coat of resin and after I’ve decided that everything is going good I take the boad to the sideyard and put it under the little shack I built off of the fence. Not a perfect place but gets the smell out of the work shop…
Oh yeah…I mark my cans of resin with the date and large letters UV CURE.
Ray, I wish you’d been here about an hour back. I just did the lam on the bottom, went well, loads of time to work dead relaxed.
When pouring the resin from the can, I was a bit nervous about light getting to the can and sending the whole lot so I had a brilliant idea…I’ll do it in the dark and guess it…Haha ha ha! Half a pint of resin over my shoes.
Just done the bottom lam, way more relaxed than with MEKP, its all set up lovely within two mins of being outside, Jeeeeez mate I aint never going back. This stuff rocks!
The smell has little to do with the catalyst/hardner. The stench is evaporating styrene in which the polyester molecules are suspended. Whether you use UV catalyst, MEKP or homer simpsons socks, the styrene emission will remain the same.
