Spaclke still seems to give me blow-thru bubbles when laminating even with a thin epoxy coat over the lam. Using the 2nd method, what ratio of epoxy resin to microballoons? Going to try this method.
I use half microballoons and half resin/hardener mix by volume. This seems to give a good consistency for "spackling" EPS.
However, you will still get outgassing even when sealing with epoxy/microballoon mix.[b] You have to control the temperature very carefully no matter which sealer you use. I like gently falling temps until the resin has set enough to handle.
Tried gentle falling temps many times - doesn't work for me. Still have the blow-thru prob.
Are you using expanded or extruded foam?
The only way I know of that expanded foam (as opposed to extruded foam) outgasses is because the blank is warming. If you're in Hawaii, I'm not sure what will solve your problem. "Fill coating" definately won't, unless you really gob it on and use little filler (microbubbles). But that's just not practical. I would say try using the epoxy/micro filler, do two coats, sanding lightly between, and make sure the blank itself, not just the ambient air, is cooling. Cooling foam will suck resin. That's pretty much a physical given. You can also try using slow hardener to reduce exotherm, but I'm pretty sure that whatever heat the kicking resin contributes once it's spread out thinly is negligable.
Good luck, brother.
Load up the epoxy with Cab O Sil M5 (preferably) or 3M K20 hollow glass microspheres (what they use in Spackle) to a point where your viscosity is equivalent to that of "Spackle". One mistake I see people making is not filling the epoxy enough and subsequently ending up with less than complete fill of the chunks/holes in the EPS blank. Cab O Sil has a weak molecular attraction so that when you apply shear (hard squeegey) the bonds between the particles break down and the viscosity reduces thus allowing you to spread a relatively highly filled thixotropic system comparatively easily. The end result is that you will put "filler" where it needs to be (in the depressions) and squeegey off all of it on the high spots.
Please let's all agree from this point forward to call the process of filling the cavities in a EPS blank "the fill coat" NOT "the Spackle coat". Spackler is a water based weak filler with little to no bond strength desinged for use as a non load carrying filler on gypsum wall board (dry wall). As such, it is a horrible adhesive link between the epoxy lamination and the blank itself and in my opinion should never be used. The laminate is only as strong as the adhesion that it has to the core - similar to the relationship between the resin matrix and the fiber size - improper fiber size results in poor wet out and adhesion of the matrix to the reinforcement thus a reduction of properties and reduced performance.
Here's an idea for all of you to try....sneak the clothes iron out to the garage and find the perfect temp that melts the EPS, but doesn't burn it and then "iron" the shaped EPS blank surface to a smooth finish (take a look at the surface finish of the hot wire cut blank before you shape it - note HOT wire = melting of EPS).
Yeah, what he said. =)
I use a mixture consistency (epoxy/microballons) roughly equal to peanut butter or possibly just a bit thicker.
I'll dab a little extra (after I'm done squeegee-ing) on any deeper-than-normal depressions/chunked areas because a little bit of the epoxy will soak into the foam anyway. After it cures, those spots can be sanded down flush to a uniform surface very easily.
The clothes iron seems like a reasonable way to smooth the shaped EPS surface assuming it could fit well with the contours of the board, but has anyone else considered that it could also help alleviate outgassing? If you were to apply some degree of heat to the shaped EPS before laminating, couldn't you in effect draw out some of the blowing gasses at a time when it wouldn't complicate your glass job?
Maybe I don't understand the nature of the problem that well or don't understand the chemistry of making foam but it seems like there is a finite amount of blowing gas in any volume of EPS foam. So applying any amount of heat can only reduce the potential for outgassing later on.
I prefer 'sealer coat', as in Aus the 'filler coat' is the same as the US 'hot coat'. Sorry, don't want to get too pedantic, but in the process you are sealing the blank, rather than filling it.
As far as mixes go, SS2 is right on the money as far as I'm concerned. After doing countless boards and other items this way, the cabosil/microballoon/resin mix is definitely the way to go. Controlled temperature is definitely a big factor, especially with eps and epoxy.
Also, if the sealer coat is done well, there should be no need to sand. Many times I applied fabric to the gelled surface, and used a squeegee push it on firmly, definitely no need to sand. It actually adheres the fabric to the foam as well, and done with some skill and care can include doing the rail laps. You can even let it cure a bit longer before applying the laminating resin and the fabric won't move around.
Makes it real easy to do multi layer boards. If you flip to do the other side laminate before the resin is cured, using the same technique, you can avoid rail lap sanding, and the cloth can be pulled tight around the rails.
This is not only a factor in getting good strength to weight ratios, but also keeps the laminate in closer tollerance with the original shape, something slack glassing and sanding can change very easily. Only better step is vacuuming.
i like your style
Wildy has some good points, after all, the whole idea by using epoxy besides the improved mechanical performance and 0 VOC is processing and we need to make the process as simple as possible. That means reduction in "steps". So far I've seen too many people hung up on "steps". A lot of the problem has to do with a combination of old poly habits and hesitation/caution when using the epoxy. Epoxy should be (and is) considered a more forgiving matrix compared to poly and its full attributes should be optimized. That not only includes maximizing the extended pot life of the resin to do a better lamination, but reducing and skipping steps (because now you can) rather than adding more.
Yes, it make a lot of sense to go straight to lam after you sweep in and then sweep OFF the fill coat and before it drys. Why wait? I don't. Fundamentally, you have only added a micro level of filled resin to the blank (only where the bead depressions are) - I don't try to "seal" the blank on fill in the holes and this is only for cosmetic purposes. Then go straight to lamination. After you get the lam tight, put down a release film on the rack that the epoxy won't adhere too (wax paper even works) and flip the board and proceed direct to the other side. Laminating both sides at once takes some skill, but it can be learned and should be. The big rap on epoxy is flip time and time in general. I consider the extended ot life and resultant cure time as a benefit not a obstacle. People have to go beyond trying to plug a new resin matrix into the same process. Adjust and optimize the porcess to suite the features of the resin.
Here's another step saving idea besides eliminating the rail grind and wait time to flip. Minimize/eliminate the sanding step. Produce a "net finish" surface by laying down a boardy, but flexible 0.30"+ film like released lexan (polycarbonate), Kapton or teflon coated fiberglass directly on top of the hot coat once your done spreading out the resin. Use a sqeegey to spread lay down the film to assure 100% contact and no air entrapment. The boardy film won't wrinkle. Wait for the resin to cure and rip the film off. Valah, you get a direct transfer of the film surface, i.e. if you use a glossy film you get mirror gloss finish surface, if you use a matt surface you get a matt surface. Basic, but these are the things peopl need to open their eyes up to in order to both take advantage of all the value/benefits that epoxy has over poly and in order for epoxy to make true and lasting inroads into production laminating. The industry needs to make a switch for the simple VOC issue alone! Think if you either eliminate all the sanding, or at least 75% of it. Talk about dust reduction! You combine that with no styrene and you might actually end up with a production environment that most people wouldn't be repulsed by.
So, everybody go out there and iron the blank smooth - no need for fill coat now, lam the bottom, let the resin kick for 30 minutes and then flip and lam the deck w/o the lap grind necessary or the wait time. Let cure o/n. Hot coat the deck and use "surface control film" - let cure o/n. Leave film on deck, flip and hot coat bottom and use a surface control film - cure o/n. Next day, rip films off of both sides, sand small parting line on rails where the film meets and ride/sell the board. Doing so eliminates at least four steps and you can synergistically add in the fin plugs/boxes in there when doing the bottom hot coat. this may be somewhat over simplified, but it is achievable! More importantly, it demonstrates some of the possibilities of how to optimize the particular matrix you chosse to use with your process. Different matrix? Think different/modified process! Now for polyurethane....
One last thought on outgassing. I'm not aware of a significant EPS outgass problem, but then not all EPS is created the same. If there is a problem all you need to do is "season" the foam before laminating. Seasoning is the process of exposing the foam to temperatures that exceed the peak exotherm temp of the resin that the foam will see. In other words, you give the foam a heat history where you have taking it to a temp above what it will see and thus drove off whatever volitiles is is going to outgass at that given temp. If you exceed the seasoning temp during lamination, expect additional outgassing. This has been a (big) issue with vacuum bag oven cured epoxy prepreg boat construction where the foam outgasses and blows the lam off the core. It hurts a little bit more when your carbon fiber 75' America's hull has disbonds all over from outgassing then when your new fish has some pin air!
Is your post strictly "theoretical" in nature or have you really built a good number of (or any) surfboards utilizing these new techniques?
Your post sounds great, and I'm curious if you have actually made this all work in a production or hobby setting....