done it a million times on urethane blanks but never tried it on EPS. does it work?
kirk
No.
Definetly not; it’ll melt.
Hi
I’ve used a clothing iron on a low heat to take shallow dents out.
K
No he hasn't. Don't try it. That would be like me telling you can pull the dent out with ACETONE. I think Karl is confused and talking about a Poly blank.
You can't pull dents out of EPS. EPS has beads that have been expanded with Penthane gas. Those beads are expanded in a huge box to make the eps slab. Once they have been expanded...that's it. The difference in eps density is all about how many beads they pack into that slab....1 lb foam is 1lb of beads...2 lb foam is 2 lbs of beads..etc, etc.
Poly foam is poured into a mold in a 2 part mixture. there is always a little room for expansion with heat on poly. Although you are making the foam weaker.
Just glass it. Or if it's a cut type ding, just fill it with dap fast n final, and sand smooth. It will glass out a bit more beige than the foam. but not too bad.
If the density depends on the weight of the ingredients (for lack of a better term), is the size of the slab an industry standard? If so, do you know what that size is? I’m just curious because I find it interesting if the foam is not categorized by the beads per cubic foot or something equally scalable.
It’s pounds per cubic foot.
Doesn’t matter the size of the billet…
To the original poster, I say go for it! You’ll have a story to tell and will have learned a lesson.
Post up pics and I’ll post up pics of the deck I tried to glass with epoxy when the outside temp was about 90*.
It was much hotter under the tent on my back deck… Wish I had the video, that’d be funny! =D
Heat kills EPS
Actually, I do it all the time. I use a digital heat gun sold by Wagner and Milwaukee using the lowest heat setting.
This only works to a point. The individual beads will puff up some with the heat, so its only good for small depressions.
And yeah, you REALLY,REALLY have to watch what your doing or the foam will shrink if you heat it too long (that also happens with polyurethane BTW).
The trick is to do quick passes over the spot so it doesn’t get too hot. The beads will swell up a little higher than the surrounding surface, which you sand back down.
This is something that takes a while to get wired, so practice on scrap foam at first.
Never touched a poly blank. It was EPS. It worked.
thanks guys. it’s a good-sized dent on the rail (happened during shipping). i think i’ll rebuild it with spackle and sand flush. rails are getting covered with carbon anyway.
kirk
Yeah, well there are acutally several good ways to put a dent in your EPS. You could try using an unpadded weight and slidding it around a bit and see if that works. But,I think the best way is to simply drop a sanding block on the deck. That is sure fire and pretty much cinches it. Everyone will notice and bring it to your attention.
Of course if you are in a hurry, when you take it from your shaping stand you can knock against the storage rack. That really works well. Or, if you have some time and don't mind waiting, one of your friends can come over and pinch the raw blank to see how firm it is. As an added bonus you might get a greasy fingerprint out of the deal.
I'm told that a really easy way to put a dent in it is to set your planner down on the foam while it is still running. I haven't tried this, but I'm sure I will at some point.
I'm sure there are other good ways to dent your EPS or your PU. Maybe some of the more experienced guys can add some tips.
Hope this helps.
ha, nice greg. yeah, and it’s 1.25 lb foam . i swear you look at that stuff wrong and it dents!
kirk
I must learn this majical trick to pull dents out of Eps foam with an iron?
Please..more info...please? or better a short youtube?
Howzit atomized,If I am right ,EPS will start to melt at around 155 degrees. Aloha Kokua
Your right. The trick is to get the eps to heat up enough to the point that the beads swell. Carefully with quick light passes at the lowest setting. You don’t want to hold the gun aimed in place 'cause you’ll fry the foam pretty quickly.
I originally tried doing it using a blow dryer, but it just doesn’t get the eps hot enough to make the beads swell.
BTW the picture of that bashed in rail. I’ve fixed a few of those by cutting out a square section around the dent and gluing in a replacement piece of foam and shaping it down to match the rail. If you’re merticulous about how cleanly you cut it and match the replacement piece to match the shape cut out, the seam will pretty much disapear when you slurry and sand it.
That dent looks pretty serious. I would follow what atomized says and
cut & paste a patch. (so to speak) rough it out with a surform and when
you sand out the ridges, you won't see much. Spackle before glassing and
it will almost disapear. I have done this once or twice on SUP's but not on 1.25lb
eps. I try to stay away from that light of material. EPS is molded from different
size beads, I have posted up a bunch of info on it before here. Around 1 lb. the
bead size is large and usually expanded in molding to just about the limit of the bead
before it collapses. The last thing you want it collapsed bead! I was sanding a blank
of 1.5 lb bead and got it too hot and had a patch about the size of my head colapse
on the bottom! (and I have a big head, lol) I don't make SUP's anymore but do longboards
out of EPS when ordered that way. I always specify 2.0 lb or heavier and that reduces
the chance of shrinkage (collapse) and pukas. Check out atomized posts on airbushing to see the
surfaces of EPS that he paints on and you will see how good it can look it handled correctly!
That rail dip is too much for spackle, heating, or filling. Either splice in a new foam section or use 2-part foaming urethane http://www.aeromarineproducts.com/boat-foam.htm . The urethane is light yellow and outgasses bad, so you’ll have to color over it and seal it well. However, it bonds so well that it’s stronger than the solid sections of eps.
That’s it. The trick, I’ve found, is getting a tight fit with the replacement part, and using very little glue… a drop or two in the center of the part… so no glue oozes out the seams. You don’t want a glue line, just a tight foam-to-foam fit.
decided to go the foam plug route.
three pics below showing foam insert installed, sanded flush and after spackle.
kirk
