I’ve spotted a big-a$$ chunk (7’x 4’x 2’) of beaded white foam that obviously was some kind of dock floatation, and I’m pretty sure I could cart it off, but is there any way to tell if it is of appropriate quality? Also, short of cutting a cubic foot of it and weighing it, is there any way to tell density? The surface is pretty dirty, but it appears that virgin white foam exists just beneath the surface, and there hasn’t been much water penetration even though it looks like it spent some time underwater. The beads are fairly large, and appear well-fused with no gaps between beads. It’s pretty springy stuff, too. I’d love to carve a few boards out of it, but I don’t want to waste fifty bucks of epoxy and as much of fiberglass if this is not good stuff. Am I better off just getting some I know is good? any help appreciated, thanks.
My two cents: if it feel real spongy, it’s propably a light density. the large beads(about 1/4"?) would normally indicate this as well. However if it’s been used as floation for a dock or something then these are usually higher density. I’d say cut out a piece at 6"x6"x6" and measure it on an accurate scale and multiply by 8 to get desity.
Anyway, you can use it for a board whatever weight it is, just glass it heavy. 3x6oz deck, 2x6oz bottom. I’ve got a board out of a very lightweight EPS that is holding up quite well, but IF you ding it you should get it out of the water ASAP.
First, try taking some 80 grit and sanding a corner edge. If it tears or pulls beads go ahead and make a new dock. If it is a smooth sand, you might be ok. Also, after cutting a blank let it dry out for a week or so to avoid the epoxy reacting badly with contaminates (water).
Fusion - We usually kind of run a thumb over the edge to see if it breaks off easy. Some experience helps here. If it does break off easily and you can see that the beads themselves haven’t torn then it’s probably not fused that well. Fusion is the most important aspect. Badly fused foam leaks and breaks easily.
Pack - Well packed foam has very little space between the beads. Looking at the hot wired surface you should see even texture without a lot of holes between the beads. The smoother the texure appears the better the pack is.
Bead size - Beads are graded A, B, C, and T. A is the biggest and generally you don’t see those much anymore. Mostly you see B or C size. Generally the fusion on B will be a little better than on C, but the pack will generally be better on C. A well fused C is the best, if you can get it. Our foamer uses a B/C bead which is an in between grade which gives us a very consistant product. The foam processing machines (generally called a press) that are being used today can also process T bead which is very small. As yet I have not seen this fused well enough. The pack is awesome though.
Density - We use every density but on a daily basis the 2# is best for most boards. It has great strength to weight ratio (much better than any urethane), has the best resistance to leaking, doesn’t have to be glassed that heavy and is best for break and dent strength. 1.5# will make some real light boards with light glassing but those boards tend to be weak and on the disposible side… they do ride awesome though. There are some manufacturers who like using 1.5# and glassing them up. This is a very reasonable product anywhere you have a lot of rocky beaches or crowds. This can also be combined with a more flexible epoxy for excellent impact (ding) strength. 1# is used when coring your laminates, like Bert does. Almost all sailboards and the Surftech boards use 1# for the inner core. I have made boards using 1# with a heavy laminate and they ride awesome and have good ding resistance. They do break easy though.
Thanks all, I think I’ll leave it be for now, the beads are pretty large and seem to separate rather than tearing, and based on Greg’s helpful post, it’s probably 3/4 or 1 lb/ft^3, maybe A or B size beads. If anybody wants it, it’s in the Fort Point parking lot next to the porta johns. (just look for the giant orange bridge, you’re real close)
BTW thanks for your help, good info and quick response Greg, the epoxy arrived in 2 days, was a joy to work with, and is bombproof stuff (I still have a little more than half left, which is burning a hole in my storage container, which is why I’m looking at big scraps of foam). I bailed in front of one of the rocks at the fort, and my new dow board bonked the rock hard, resulting in nothing but a small crack in the tip of the nose. I’ll post details on this one (my third backyard board) in the resources section, as soon as I finish “testing” it, and take some pictures. There’s a hefty south in the water, and a buddy and I are going camping, should have thorough info by then!