Lots of theory was cast around ou a thread below about polyurethane boards “displacing” buoyancy “toward the stringer”. I’ve held my tongue (keyboard) through most of the spin on this subject. People have a right to puff their products in an effort to sell them. But the displacement theory as described on a thread below is wrong, especially when you try to apply it across blanks and manufacturers. Just for starters, the denser, stronger stringer and center fin lie along the center of a surfboard. Then… When filling a blank mould all of the PU liquid expands which doesn’t encounter resistance. When the PU resin in the center of the mold expands to the deck and hull, it encounters resistance. The resin can’t expand past the mold, and the pressure of the expanding foam behind it won’t let it regress. The PU foam ant the deck and hull merely compresses, or fails to fully expand. Conversely, when the PU resin starts to expand into the rail cavity, it doesn’t reach ANY resistance until it fills At Least 10 times the the volume as the resin expanding into the deck and hull. If left to its own devices this formula would make PU rail foam at most ONE TENTH the density of PU deck and hull foam. I’m sure Grubby Clark’s and other manufacturers’ “scientists” have come up with some clever methods of injecting and spreading PU resin which move more of the PU resin into the rails. But the effect of lighter PU rails remains to some degree. Lack of consistent over large volumes of PU foam is endemic to the PU expansion process. PU rail foam is narrower than center foam. This means you have a much higher proportion of dense surface foam to lighter interior foam in PU blank rails. Lets assume that PU blank manufacturers’ spin holds true. That PU blank density increases toward rail skin exactly as it increases to deck and hull skin. Hello? You cut the rail foam off. If PU blank density is inconsistent in the way Herb Spitzer says, then finished PU rail foam is much less dense than the average foam in the remainder of a PU surfboard. I’ve heard that PU blank manufacturers use some pretty extreme measures to try and give PU blanks as much density consistency as the system will allow. But the fact remains, PU blank density is inconsistent, inside blanks, between blanks of any manufacturer, and across manufacturers. I’d like to see manufacturer(s) join us here by explaining the measures taken to improve density consistency. But I remain convinced that shapers, home builders and retail buyers have no reason to expect ANY consistency in PU density through any board, from one part of a board to another, or brom one manufacturer to another.
Lots of theory was cast around ou a thread below about polyurethane boards > “displacing” buoyancy “toward the stringer”.>>> I’ve held my tongue (keyboard) through most of the spin on this subject. > People have a right to puff their products in an effort to sell them. But > the displacement theory as described on a thread below is wrong, > especially when you try to apply it across blanks and manufacturers.>>> Just for starters, the denser, stronger stringer and center fin lie along > the center of a surfboard. Then…>>> When filling a blank mould all of the PU liquid expands which doesn’t > encounter resistance. When the PU resin in the center of the mold expands > to the deck and hull, it encounters resistance. The resin can’t expand > past the mold, and the pressure of the expanding foam behind it won’t let > it regress. The PU foam ant the deck and hull merely compresses, or fails > to fully expand. Conversely, when the PU resin starts to expand into the > rail cavity, it doesn’t reach ANY resistance until it fills At Least 10 > times the the volume as the resin expanding into the deck and hull. If > left to its own devices this formula would make PU rail foam at most ONE > TENTH the density of PU deck and hull foam.>>> I’m sure Grubby Clark’s and other manufacturers’ “scientists” > have come up with some clever methods of injecting and spreading PU resin > which move more of the PU resin into the rails. But the effect of lighter > PU rails remains to some degree. Lack of consistent over large volumes of > PU foam is endemic to the PU expansion process.>>> PU rail foam is narrower than center foam. This means you have a much > higher proportion of dense surface foam to lighter interior foam in PU > blank rails. Lets assume that PU blank manufacturers’ spin holds true. > That PU blank density increases toward rail skin exactly as it increases > to deck and hull skin.>>> Hello? You cut the rail foam off.>>> If PU blank density is inconsistent in the way Herb Spitzer says, then > finished PU rail foam is much less dense than the average foam in the > remainder of a PU surfboard.>>> I’ve heard that PU blank manufacturers use some pretty extreme measures to > try and give PU blanks as much density consistency as the system will > allow. But the fact remains, PU blank density is inconsistent, inside > blanks, between blanks of any manufacturer, and across manufacturers.>>> I’d like to see manufacturer(s) join us here by explaining the measures > taken to improve density consistency. But I remain convinced that shapers, > home builders and retail buyers have no reason to expect ANY consistency > in PU density through any board, from one part of a board to another, or > brom one manufacturer to another. blah blah blah. me thinks thou dost protset too much. beer coolers, cute little water toys, dock floats, packaging material, home insulation, pop-out surfboards. what a frickin line-up of high pefroemance products. wonder if thats why so many of the hottest rippas say that eps dont feel natural? its queerstuff.
Packaging material? I have no idea what you’re talking about that could relate to the subject, polyurethane blank consistency. Sorry you couldn’t keep up. I assumed lots of people wouldn’t. I mistakenly assumed that those people would be intelligent and considerate enough not to interrupt with drivel.
Packaging material? I have no idea what you’re talking about that could > relate to the subject, polyurethane blank consistency.>>> Sorry you couldn’t keep up. I assumed lots of people wouldn’t. I > mistakenly assumed that those people would be intelligent and considerate > enough not to interrupt with drivel. you did well you must remember that 85%percent of this sites veiws are from very small time recreational board builders… im not being negative to any of you… most of you would and do appreciate intelligent infomation… if some one writes crap like that dribble they are one of those people who cant let go of thier nuts and dont like any one getting infomation that will help them out. they have this inbuilt insecurity that they will lose profit if someone else gets just one of there orders… thats just showing thats why they do what they do… not for love or intellectual growth but for sole financial gain you are doing what this site was designed for… the sharing of knowledge to bring us all forward…
Question? has any one ever tried making poly foam in blocks like styrofoam & cutting them the same way? Can you produce a block of poly with an even consistant density? What would be the ultimate foam core???
Hi Ray - I don’t have the answer to all of your questions but I know that before blank making really evolved, foam blanks at some point were cut out of rectangular blocks. I have an old set of “do-it-yourself” plans that show very clearly a guy with a saw held horizontally cutting the rocker into a blank. The instructions state to use polyester resin when glassing so I assume the foam is polyurethane.
Lots of theory was cast around ou a thread below about polyurethane boards > “displacing” buoyancy “toward the stringer”.>>> I’ve held my tongue (keyboard) through most of the spin on this subject. > People have a right to puff their products in an effort to sell them. But > the displacement theory as described on a thread below is wrong, > especially when you try to apply it across blanks and manufacturers.>>> Just for starters, the denser, stronger stringer and center fin lie along > the center of a surfboard. Then…>>> When filling a blank mould all of the PU liquid expands which doesn’t > encounter resistance. When the PU resin in the center of the mold expands > to the deck and hull, it encounters resistance. The resin can’t expand > past the mold, and the pressure of the expanding foam behind it won’t let > it regress. The PU foam ant the deck and hull merely compresses, or fails > to fully expand. Conversely, when the PU resin starts to expand into the > rail cavity, it doesn’t reach ANY resistance until it fills At Least 10 > times the the volume as the resin expanding into the deck and hull. If > left to its own devices this formula would make PU rail foam at most ONE > TENTH the density of PU deck and hull foam.>>> I’m sure Grubby Clark’s and other manufacturers’ “scientists” > have come up with some clever methods of injecting and spreading PU resin > which move more of the PU resin into the rails. But the effect of lighter > PU rails remains to some degree. Lack of consistent over large volumes of > PU foam is endemic to the PU expansion process.>>> PU rail foam is narrower than center foam. This means you have a much > higher proportion of dense surface foam to lighter interior foam in PU > blank rails. Lets assume that PU blank manufacturers’ spin holds true. > That PU blank density increases toward rail skin exactly as it increases > to deck and hull skin.>>> Hello? You cut the rail foam off. How much rail do you cut off though? - check out Clark’s close tolerance blanks: http://www.clarkfoam.com/spec.HTM The 6’4" R is 20" x 2 1/2" nose 14" Tail 15". You’d only lose about 3/4 inch either side - at the mid point for an 18 1/2" wide board. Anyone got a recently snapped PU board they could do a totally unscientific finger poke test and tell us whether the blank is less dense at the core and or the rails? I’m just trying to make sense of Herb’s displacement theories. I’ve got no money in either PU or Styrofoam. Just want to know what will work best and why.
Anyone got a recently snapped PU board they could do a totally > unscientific finger poke test and tell us whether the blank is less dense > at the core and or the rails? I’ve got half a 10-1y three stinger one of my customers broke in half last year. I will give it a poke & see whats up…tune in later for the results.
…But Napalm has a way of doing that…sheesh! …But seriously folks,The theories I posted were past on to me by a reputible source,and I concur with those theories. Past that,people are going to ride what they feel is the best for them,durability,and cost are also conciderations, as well as ride,sometimes more. I was thinking epoxy on poly foam,Noodle whatz up with this combo?Heavy?Glass amounts? and DURABILITY???PROs and CONs.Herb
Packaging material? I have no idea what you’re talking about that could > relate to the subject, polyurethane blank consistency.>>> Sorry you couldn’t keep up. I assumed lots of people wouldn’t. I > mistakenly assumed that those people would be intelligent and considerate > enough not to interrupt with drivel. sorry noodle, i`ll type it slower for you: beer coolers, cute little water toys, dock floats, packaging material, home insulation, pop-out surfboards are all made of EPS. you connnect the dots.
sorry noodle, i`ll type it slower for you: beer coolers, cute little water > toys, dock floats, packaging material, home insulation, pop-out surfboards > are all made of EPS. you connnect the dots. I made no claims about EPS. If I do, I won’t make them to an asshole like you.
Herb, Unlike the jerk above, no offense taken, as none was meant. I merely disagree with your theory that inconsistencies in poly blank densities are consistent or even predictable. I’ve read first hand accounts online from poly blank factory owners showing that they employ different chemicals, temperatures and methods of injecting and expanding poly resin into blanks. They employ these means for the purpose of reversing natural inconsistencies in foam density inherent in the molding process. We each pointed at patterns of natural poly density inconsistency, when used in a surfboard. Those patterns are in direct opposition to each other. We have some blank manufacturers spraying resin into molds by hand, some by machine. We have blanks sprayed the same ways which differ widely in physical characteristics. We have spray nozzles with differing patterns, and resins with differing composition. We also have chemical and organic solids being added to the poly resin. Don’t you think, no matter which of our theories of natural shaped blank inconsistencies is correct, after some manufacturers do their best to reverse the natural trends, and some don’t… Don’t you think that their might be just a little… Or a LOT!! of variances in the patterns of density distribution of polyurethane blank foam? Be honest, now. Your credibility could be at stake. Stake or no, whatever density is inherent in poly blank rails, you will remove it when you cut off the blank rails. Most hull densities remain relatively unaffected by shaping, but shapers remove only 1/8" of the hull foam surface. Anything more, like the 1/4" of foam taken from lots of decks, and you tremendously reduce the density and strength in a VERY predictable area of the blank. So cut 3/4 inch off each rail, unpredictable areas of blanks, and… you can put your calculator away. Figuring the resulting density inconsistencies from one board to another would be like nailing jelly to a tree. It can’t be done. Epoxy does make a short-lived passable covering for poly blanks, but the combination makes for a very stiff board. Epoxy glass is so stiff that it needs a flexible substrate. Beaded EPS is flexible on a small scale. In other words, EPS is resillient like (but not as much as) foam rubber. Unlike PU, when you squish beaded EPS, it springs back. That’s important to epoxy glass. When you press on epoxy glass it springs back. If beaded EPS is underneath depressed epoxy glass, both glass and foam will bend back together. PU foam is great at large scale flex for your first few surf trips. But PU foam is notoriously bad at small scale resilliency. PU foam is relatively brittle If you press on PU foam hard enough, or enough times, it turns to powder. Polyester glass is a good match for that property. Polyester glass is also brittle, less resillient. Take the combination of poly glass over poly foam. Press on the poly/poly combination hard enough or long enough. The poly foam dents, it may even turn to powder. The poly glass stays dented into the foam. It might even crack, but the board remains relatively rideable. Now put epoxy glass over poly foam. Press on the glass surface hard only a few times. The poly foam stays depressed, and the bond with the epoxy glass turns to powder. The epoxy glass springs out of the poly foam depression, and starts a chain reaction which could quickly delaminate a large section of glass. I wouldn’t recommend combining epoxy glass with polyurethane blanks on any retail board, even to try and combine the strength of epoxy with the large scale feel of a polyurethane blank. From the accounts I’ve read and the people I’ve talked to, you’d be making your client a new surfboard very soon. But I can see why people who get only a few weeks of surfing out of their poly/poly potatoe chips might think that a short-lived epoxy/poly board would represent an improvement.
Herb, Unlike the jerk above, no offense taken, as none was meant. I merely > disagree with your theory that inconsistencies in poly blank densities are > consistent or even predictable. I’ve read first hand accounts online from > poly blank factory owners showing that they employ different chemicals, > temperatures and methods of injecting and expanding poly resin into > blanks. They employ these means for the purpose of reversing natural > inconsistencies in foam density inherent in the molding process.>>> We each pointed at patterns of natural poly density inconsistency, when > used in a surfboard. Those patterns are in direct opposition to each > other. We have some blank manufacturers spraying resin into molds by hand, > some by machine. We have blanks sprayed the same ways which differ widely > in physical characteristics. We have spray nozzles with differing > patterns, and resins with differing composition. We also have chemical and > organic solids being added to the poly resin.>>> Don’t you think, no matter which of our theories of natural shaped blank > inconsistencies is correct, after some manufacturers do their best to > reverse the natural trends, and some don’t… Don’t you think that their > might be just a little… Or a LOT!! of variances in the patterns of > density distribution of polyurethane blank foam?>>> Be honest, now. Your credibility could be at stake.>>> Stake or no, whatever density is inherent in poly blank rails, you will > remove it when you cut off the blank rails. Most hull densities remain > relatively unaffected by shaping, but shapers remove only 1/8" of the > hull foam surface. Anything more, like the 1/4" of foam taken from > lots of decks, and you tremendously reduce the density and strength in a > VERY predictable area of the blank. So cut 3/4 inch off each rail, > unpredictable areas of blanks, and… you can put your calculator away. > Figuring the resulting density inconsistencies from one board to another > would be like nailing jelly to a tree. It can’t be done.>>> Epoxy does make a short-lived passable covering for poly blanks, but the > combination makes for a very stiff board. Epoxy glass is so stiff that it > needs a flexible substrate. Beaded EPS is flexible on a small scale. In > other words, EPS is resillient like (but not as much as) foam rubber. > Unlike PU, when you squish beaded EPS, it springs back. That’s important > to epoxy glass. When you press on epoxy glass it springs back. If beaded > EPS is underneath depressed epoxy glass, both glass and foam will bend > back together.>>> PU foam is great at large scale flex for your first few surf trips. But PU > foam is notoriously bad at small scale resilliency. PU foam is relatively > brittle If you press on PU foam hard enough, or enough times, it turns to > powder. Polyester glass is a good match for that property. Polyester glass > is also brittle, less resillient. Take the combination of poly glass over > poly foam. Press on the poly/poly combination hard enough or long enough. > The poly foam dents, it may even turn to powder. The poly glass stays > dented into the foam. It might even crack, but the board remains > relatively rideable.>>> Now put epoxy glass over poly foam. Press on the glass surface hard only a > few times. The poly foam stays depressed, and the bond with the epoxy > glass turns to powder. The epoxy glass springs out of the poly foam > depression, and starts a chain reaction which could quickly delaminate a > large section of glass. I wouldn’t recommend combining epoxy glass with > polyurethane blanks on any retail board, even to try and combine the > strength of epoxy with the large scale feel of a polyurethane blank. From > the accounts I’ve read and the people I’ve talked to, you’d be making your > client a new surfboard very soon.>>> But I can see why people who get only a few weeks of surfing out of their > poly/poly potatoe chips might think that a short-lived epoxy/poly board > would represent an improvement. oh for sure. that`s why everyone everywhere is always takin about their rippin new eps boards. yeah yeah yeah. if they were really all that and more then all the top pros would be surfin them against each other. get real. money talks- bullshit walks. period. plus herbs right on. you all go on an ride what yall like. H.B. SMACKDOWN!!!
oh for sure. that`s why everyone everywhere is always takin about their > rippin new eps boards. yeah yeah yeah. if they were really all that and > more then all the top pros would be surfin them against each other. get > real. money talks- bullshit walks. period. plus herbs right on. you all go > on an ride what yall like. H.B. SMACKDOWN!!! Thank you for your treatise on exactly where we can find the inconsistencies in surfboards. Now please inform me of the differences between hand shaped boards and factory mass produced poly/poly boards, big shot. Tell me something. If you owned the second largest surfboard company in the world, and made pros brand new sticks for EVERY STINKING CONTEST, how could you get off telling anybody that proves your boards are just the thing for them. People like you will continue selling total crap for babe bait, but nobody can see ‘em or ding 'em on some gremmie’s bedroom wall. You’d better call rack board 911 right now jerk. “sceptic”?! Give me a break. Support your local shaper.
Herb - Noodle, You both have way more experience with this than me - so help me out here. Everything I’ve read about PU says density is inconsistant, experience tells me the same - I’ve had a board that folded like wet cardboard in a 3 foot japanese beach break and I’ve got another that has taken a few poundings in 8 foot Winki pop (Bells) and is still in one piece, both PU/poly. I’m thinking about making a styrofoam board and glassing it with s-glass and this DHP stuff when it becomes available (there’s also an Australian non-epoxy resin recently introduced I might look at). I figured the DHP resin and s-glass would have more flex than epoxy. So the board would feel more like the PU ones I’m used to. I was just going to make it a bit thinner to accomodate the extra bouyancy of the styro. But if PU feels the way it does because of the varying density of the foam then this idea isn’t going to work out.
Herb - Noodle, You both have way more experience with this than me - so > help me out here.>>> Everything I’ve read about PU says density is inconsistant, experience > tells me the same - I’ve had a board that folded like wet cardboard in a 3 > foot japanese beach break and I’ve got another that has taken a few > poundings in 8 foot Winki pop (Bells) and is still in one piece, both > PU/poly.>>> I’m thinking about making a styrofoam board and glassing it with s-glass > and this DHP stuff when it becomes available (there’s also an Australian > non-epoxy resin recently introduced I might look at). I figured the DHP > resin and s-glass would have more flex than epoxy. So the board would feel > more like the PU ones I’m used to. I was just going to make it a bit > thinner to accomodate the extra bouyancy of the styro. But if PU feels the > way it does because of the varying density of the foam then this idea > isn’t going to work out. See my foam test in the archive foam tests2 PIC foam tests PIC
Thank you for your treatise on exactly where we can find the > inconsistencies in surfboards. Now please inform me of the differences > between hand shaped boards and factory mass produced poly/poly boards, big > shot.>>> Tell me something. If you owned the second largest surfboard company in > the world, and made pros brand new sticks for EVERY STINKING CONTEST, how > could you get off telling anybody that proves your boards are just the > thing for them. People like you will continue selling total crap for babe > bait, but nobody can see ‘em or ding 'em on some gremmie’s bedroom wall.>>> You’d better call rack board 911 right now jerk.>>> “sceptic”?! Give me a break. support your local shaper mmmm thats a great thought… im hoping this site is ego free. lets get back to learning from each other not writing off each others ideas / beliefs / concepts.>>> Support your local shaper. http://www.feraldave.com
Question? has any one ever tried making poly foam in blocks like styrofoam > & cutting them the same way? Can you produce a block of poly with an > even consistant density? What would be the ultimate foam core??? Polyurethane foam can be formed into blocks. There are many companies that do. If you free blow the foam, ie not into a compressed mold, it will have the same density through out. The advantage of haveing a density gradient through the blank is that you can make a lighter board. The weight of the foam depends on the formulation. They make Urethane foam from 1lb density to 10lb density. (pounds per cubic foot) The average surfboard blank is around 2lb density.
Thank you for your treatise on exactly where we can find the > inconsistencies in surfboards. Now please inform me of the differences > between hand shaped boards and factory mass produced poly/poly boards, big > shot.>>> Tell me something. If you owned the second largest surfboard company in > the world, and made pros brand new sticks for EVERY STINKING CONTEST, how > could you get off telling anybody that proves your boards are just the > thing for them. People like you will continue selling total crap for babe > bait, but nobody can see ‘em or ding 'em on some gremmie’s bedroom wall.>>> You’d better call rack board 911 right now jerk.>>> “sceptic”?! Give me a break.>>> Support your local shaper. what good isa stick if it doesnt have the right look? if it isnt a babe magnet an have “that” totally rad look, then its time to lay the smack down for another one that does. sometimes a board isnt “magic” because you havent put ALL the most core stickers on it!!! surfin would be NOWHERE if todays hottist cues werent babe bait!! that aint Viagra, thats progressive!!!
…But Napalm has a way of doing that…sheesh!>>> …But seriously folks,The theories I posted were past on to me by a > reputible source,and I concur with those theories.>>> Past that,people are going to ride what they feel is the best for > them,durability,and cost are also conciderations, as well as > ride,sometimes more.>>> I was thinking epoxy on poly foam,Noodle whatz up with this > combo?Heavy?Glass amounts? and DURABILITY???PROs and CONs.Herb I’ve had a couple of poly/epoxy combo boards.On paper it seems like a godd combo strength and weight wise, and in fact they do feel real good.However, on one of them the glass would chip off in chunks instead of dent, like volan for example.I think the other one is still curing(it’s about 10 years old)the glass is is sucking up the foam around the stringer causing the stringer to rise above deck line.kind of looks like an old longboard that has been left out in the sun for 30-40 years.I don’t think I’ll try that combo again. Matt