I’ve been doing some searching on sealing EPS. A lot of the posts are a year or two old and for the really light EPS. I’ve read some say they don’t seal EPS that’s 2 lbs. or heavier.
Now that denser and harder EPS has been around a while, what is everyone doing with it? Are you still sealing, sealing only with tints, not sealing at all, what?
I’ve got a 2.5 lb. blank to shape so I’ve got to figure out what I’m going to do.
Thanks for the help.
Anything over 2 lb you only need to seal it for the cosmetic appearance. If your doing color, paint or tint, seal it.
You need to seal 2 lb though.
-Jay
That’s a great time to do an epoxy color foam stain!
D
C’mon people. I know there are plenty of you out there using EPS at 2+ lbs. Sealing, not sealing?
I seal with 3M microspheres. but it is an optional thing to do with high density foam. try one sealed and one not sealed. If you don´t seal laminate wet, not dry.
Dave,
Um, wet or dry? I’ll just point out the obvious and let you straighten me out. Aren’t all laminations wet?
I don’t seal 2lbs. I think it’s a waste of time. How much weight gain is it going to give you? I think you get better protection against pressure dents by not sealing. On lighter foam and if you are extremely picky abuot weight or do color work you should propably seal.
regards,
Håvard
I think the main problem with not sealing 2lbs is that if you pull the laminate tight, which is desirable for strength, then it is also relatively dry. Now, if voids in the foam suck resin out of your laminate you’ll end up with soft spots in the lam. You could do a cheater coat but then you might as well seal. Same amount of work and it gives you the option of adding filler to your seal coat for reduced weight. I seal 2 lbs, but I’m pretty sure many of the pros don’t - probably to save time and materials. Look at the EPS boards in the shops and they don’t look sealed.
Dave,
Um, wet or dry? I’ll just point out the obvious and let you straighten me out. Aren’t all laminations wet?
I am sure there is something about this in the archives. Failing that a google search would most probably help you. But okay, a dry lam is when you lay the cloth over the work and apply the resin on top. A wet lam is when you brush resin on the work first and then place the cloth on the surface and squegee more resin until the cloth is saturated. why do this? Lets see if you can figure that one out. A hint: EPS has a “sucky” reputation…
I used to seal my EPS. 1# and 2#. Then I read further and haven’t sealed my last 8 one pound EPS BalsaComps that I’ve done. 9 mo. later and the first non-sealed board, that I use the most, has no preasure dents, delams, nada! And, it’s 10’, 16 lbs… the latest board is 10’ and 14 lbs!
Why use EPS/Epoxy if you want to keep making pupe-type boards?
Les
Dave,
I thought it had something to do with that, but didn’t want to assume. I’ve only glassed with poly so I’m not familiar with the epoxy techniques. Hence this thread.
Okay, so, if light and no seal, may want to wet lam’ keep the resin from being sucked out of the cloth?
if you’re gonna do that…why not just mix in some glass bubbles and seal…then lay cloth and lam when it’s gelled.
I think the main problem with not sealing 2lbs is that if you pull the laminate tight, which is desirable for strength, then it is also relatively dry. Now, if voids in the foam suck resin out of your laminate you’ll end up with soft spots in the lam. You could do a cheater coat but then you might as well seal. Same amount of work and it gives you the option of adding filler to your seal coat for reduced weight. I seal 2 lbs, but I’m pretty sure many of the pros don’t - probably to save time and materials. Look at the EPS boards in the shops and they don’t look sealed.
I would think filling the voids in the EPS happens relativly fast, so by spreding the resin and letting the glass and EPS soak you would be pretty much in the clear. On lighter foam I can see the problem, however it’s more of an adjustment to how much resin to remove from the cloth. You could do a test to see how much resin it socks, do a small panel with colored resin and cheater, filler and no coat, then lam. Cut to equal size patches, weight. Also cut them in half and see how far in the resin penetrates. I know on light EPS the resin penetrates deep, down to 1/2" if you let it.
regards,
Håvard
I work for a company that manufactures EPS and we make a specific 2# foam for the surf biz. (It is made from an entirely different bead than our construction foam.) When we started out last year most of my customers did a seal coat of either DAP or epoxy with micro-balloons before laminating. As of a few months ago hardly anyone using our 2# seals a blank anymore unless they are doing an airbrush or tint job. They found the foam does not soak liquid (of any sort) any more than a good poly foam.
I found while developing our EPS that while increasing the density did a lot to mitigate the soak, just getting to the 2# density threshold was not a guarantee that the stuff would not “soak”. What really makes the difference is the “pack and fusion” of the beads. Talk to anyone with a shaping machine that uses the suction cup type fixtures (ie ProCam, Channin, KKL, I-Shapes, O’Keefe, etc.) and they will tell you that the density of the EPS they are trying to cut is not the most important feature of the EPS. Their concern is whether the stuff will allow air to be sucked through the blank and not be held in place during the machining. Their logic, along with the board builder is flawless, if the EPS allows the vacuum fixtures to suck air through the blank then water will also be able to penetrate the stuff.
Trial and error is still a big factor in using the newer materials and we are still learning as we go with our own product. Thankfully we have a great group of customers, large and small, that have shared a lot of their experience with us and we have had very, very few problems.
I have never posted anything on Sway’s before but have followed a lot of the discussions over the last couple of years. Since getting back in the industry after a long stint elsewhere, I have waited until I felt I had gotten enough practical experience with the EPS to be able to give some honest advice about the stuff instead of a sales pitch. I am pretty stoked with how the stuff has worked over the course of this last year in the boards I have seen made and ridden.
Hope this helped a little.
Steve
balzac,
Thanks. Great input. Some else once told me that fusion is a big factor in EPS quality.
I guess what I’m hearing is that if it’s 2 lbs. or more, don’t seal on clear, seal on tints and paint. Since I’m tinting, I’ll do a search on spakle vs. microballons for tinting.
I appreciate all the input from everyone. Like I said in the opening, most of the posts I’d found regarding sealing were on lighter foams. Since EPS is evolving and denser and tigher foams are being used, I wanted to hear what people are doing now.
Sway’s is the place.
Steve,
Is there a forseeable chance that a 2# or greater density blank will ever be produced using the T size bead that is used in coffee cups. My impression is that it would have excellent cosmetic properties. Any comment, or insights you can share? Welcome aboard!
Bill,
What do you think the outcome will be of reducing the size of the beads? I know with ceramics and metals reducing grain size increases most physical properties (strength, toughness, and modulus). It seems like those coffee cups have a much greater ability to be deformed, yield point. I have thought about that same issue and drew the same preliminary conclusion (coffee cups = smooth)
-Keenan
Keenan,
This is unknown territory for me. I did receive a PM from a more knowledgable person, on this topic. The very small size of the T size bead, in something as thick as a blank, will fuse at the surface, and prevent penetration of the steam to the core area, leaving unfused beads. Not a good situation. The industry is well aware of what surfboard builders are seeking, and I suspect there are a good many people working on the fuseing issue. All the benefits you describe for smaller grain size, would also occur with smaller beads, IF they could be fused properly. Maybe in time…
Keen,
Keep in mind that coffee cups aren’t meant to be shaped, etc. They’re also dirt cheap. I’m sure coffee cup makers have a whole different set of objectives.
That doesn’t negate the idea of smaller beads being better. They’d just need to be a different type or handled differently.
Steam not reaching the center? Hmmm? Retractible steam injectors? I’m sure it will evolve. Would be nice to have a small tight grain in the foam.
Bill,
We do use a smaller bead than most in the industry at this point and it is in fact, smaller than the stuff used in coffee cups. Way, way, way smaller! The difference is that coffee cups are “shape molded” and we mold a big billet and then cut the blank out of it. The outside of our billets before cutting look just like the coffee cups but tighter grained.
I have a competitor that makes blanks in shape molds and does a nice job of it. However, when the blanks are planed they have a completely different feel to them because of the different bead size, pack and fusion. In short, just because they start out with a smooth finish is no indication of the pack and fusion. I started out thinking that the shape mold process would be the best way to make EPS blanks. I changed my view after we got down the road a bit and decided that the advantages of the billet molded and hot wire cut unit is a better and infinitely more versatile way to make these puppies.
It will be very interesting to see where the next couple of years will take us.
Steve