We all know the demise of Clark Foam ushered in a new world for both experienced industry shapers and DIY’ers. Recently I’ve had the opportunity to shape some of the available foams and here is a some input on them.
First up was the MDI (Methyl Phenyl Di Isocynate) ‘bio-foam’ from Homeblown. This foam is originally from the UK since around the 80’s and their formula is now available in the U.S. and other locations. They use a plant base devoid of the chemical toulene otherwise known as TDI blanks (Clark Foam was a TDI - Toulene Di Isocynate). They have not made it generally known what the plant base is, perhaps soy. Another MDI foam has been made available to me to try shaping from the guys at Ice 9: their blanks are a sugar base MDI. Initially I will say I like that they have a good variety of weights available using the boxing categories (fly, feather, etc.) to describe their densities. These blanks are poured in aluminum molds vs. concrete. The ones I received have very smooth finishes on them out of the mold and even a raised logo as part of the blank. They showed me some cool options for stringers including colors. Pricepoint is very competitive. A quick note on a recent call from them: do not overheat the layups or while setting in FCS or other fin inserts, boxes, leashcups, etc. (makes sense, sugar melts). Be especially careful on inserts if you are using milled fibers for your reinforcement…MF will heat up the resin/catalyst mix even more so. Their current recommendation is to not exceed .7% catalyst to resin ratio. If you are using UV resin for layups and adding catalyst to UV in order to set your logo laminates while glassing, be careful not to exceed .5% catalyst for the UV resin. Also very dark color schemes could present a problem. They are aware of this and may make some adjustments. More on these when I shape my first one next week.
The Homeblown has overall consistent rigid foam. After shaping several I noticed some inconsitencies (mainly on the bottom, where I removed most of the foam…a typical practice for experienced shapers that restructure blanks and primarily used Clark’s Foam. Thicknessing from the bottom was prevalent due to the gradient of Clark’s foam (harder crust, softer core) in order to produce a stronger finished deck resisting pressure dents from heels, knees, and other blows.
Using sharp blades on a full size Clark Hitachi planer, I found my usual planing speed would result in considerable tearing of the foam. By slowing down approximately 40% to 50% on forward cuts, the foam planed very nice and with no cheddar; although on one blank, “cheddar” resulted in some spots regardless of what pace I was mowing at. I do not have an abrasive drum on one of my planers as they are not available for the larger Clark Hitachi model (I have 2 of them). I do not like the short planers as they do not have ‘blocking action’.
Good quality abrasives make the block sanding a much more enjoyable experience. I recently purchased some strips of abrasive at the local Ace hardware store and the stuff was purple colored flexible strips that the coarser grits (60 grit) was quoted as being a great paint stripper. I used Tacky disc adhesive and put the stuff on one of my sanding blocks and it has worked very well on Homeblown as well as other foams. Before that, I found myself muscling the HB foam with 50 grit open coat production paper…also some disc sanding…which it does quite well and experienced shapers that disc sand may prefer. The HB foam “saws” reminiscent of the old Dow extruded foam…which inexperienced shapers may like because there is more room for error before realizing the foam is gone and they (you?) have screwed up and your mistake is now on the floor!
There had been some previous comments from craftspeople about dents showing up on their HB or MDI blanks…I had yet to shape any, and attributed this to inexpeience in handling blanks. I was wrong. I found some dents on mine as well, and was very suprised as the foam is purported to have “superior compression” than that of a Clark (Clark is frequently used as the standard for comparison). Sorry, but I know how to handle blanks, and I am now concerned as to the why pressure dents showed up.
I was also told that the blanks may shape out a little heavier than some other blanks (like U.S. or Surfblanks) but that the result will be light due to less resin absorption after glassing. And also, the option of lightening the usual glass schedule due to it’s inherent superior compression qualities. I didn’t find this to be true. Suffice to say, that a heavier core makes for a heavier board…not a problem if that is what you want.
U.S. Blanks & Surfblanks America (Midget’s foam): I found both of these foams comfortable to shape at my regular pace. If one was easier than the other, I would say the U.S. blank was the closest to a Clark. There has been a lot said about quick shaping foam not being as good for the surfer. I don’t know if I really believe that. Also the new mantra blank suppliers are ‘selling’ to everyone is how much “livelier” their foam is compared to their competitors. There has also been a huge focus on flexural characteristics of the foam. I think if you are talking about stringerless boards, you could begin to quantify this. Then you have alternative methods (parabolics, etc.) of flex and stiffening a board in specific places or gradient flex patterns…but this presents a myriad of dynamics that largely is a matter of personal preference. Bottom line: too many variables to quantify on a whole for the average consumer. I suppose someone out there could compile results but even then they would merely be stated opinions: is flexible or stiff better for a beginner? What flex configuration is optimum for fast hollow waves? Slow mushy wave? Windswell wave? Groundswell wave? Waves are as individual as people.
Back to foam…I think you have to know yourself to decide which foam works for you. Some shapers will only want to use the new superfused C bead EPS foam and stick with epoxy glassing. Others will love the ‘harder’ MDI foam that is like sawing action when sanding down. Some will prefer the softer larger EPS that tears out beads easier. Some will want the extruded because they are masochists. Some will want the closest thing that ressembles Clark Foam.
My personal preference for an everyday PE board is the US or Surfblanks. Why? Because they allow me to work at the comfortable planing speed I am so accustomed to working at. This is critically important to me because I have a rhythm and having to slow down 40% or 50% (or even 30% for that matter) basically throws me off. I want fluidity, and I find that fluidity is somehow tied directly into my creative thinking process.
All I know is what is right for me, and “good things happen with speed” is my mantra.
Added on 8/17/07:
Furthermore, I learned in the era before close tolerance blanks…when reading foam was of critical importance; both in terms of maintaing structural integrity and making a living. I adhere to the ‘less is more’ school of shaping, where a minimum of bands cut is accompanied with a roughing out technique of using the planer as a more precise surform. This blending technique employs and is cognizant of the anatomy of the planer itself and the dynamics inherent to forward and backward cuts…both have their place and purpose, and I use both equally to my advantage. In other words, it is a good thing to know the difference between your planer’s toe and tail. In addition, sideways ‘roller cuts’ can be used in the ear and shoulder area of the blank allowing for rail taper and volume distribution; this takes steady hands and some confidence. I barely use a surform if at all…no need with the planer and sanding blocks. I am very big on blocking as a parabolic arc is comprised of straight lines.
The biggest problem in shaping is overshaping…that includes you computers out there. As far as CNC shaping…density gradients can present a real problem unless registration is right on…otherwise the system is dependant on uniform cell density to eliminate overshaping the deck (or bottom for that matter). The only foam I currently know of that is uniform throughout is the higher grade EPS. I don’t think any of the PE manufacturers can prove consistent cell density through their entire blank. If I am wrong, please step up and be counted…actually extruded is probably consistent throughout? However as I eluded to earlier, if you like shaping extruded you are either a masochist or nuts, or both…anybody that wants to change my mind on this will have to supply me with a new extruded blank that makes me feel warm 'n fuzzy.
I will update this later on as I shape some other foams. As I mentioned, Ice 9 supplied me with two blanks (a 10’3 and a 6’8") both in different weights. I will be compiling data for them in a shaper’s log for future reference which will include raw blank weigh in, finish shaped weight, 1st lam weigh in, 2nd layup weigh in (with glass schedule), hotcoats, etc The guys at Ice 9 are great folks and said they would also calculate the weight of the blanks minus their stringers. This is very significant on the 10’3 as it has a 3/8" wood stringer and that is a mondo amount of weight right there. How much lighter would the same blank weigh with a divinycell stringer or no stringer and warp glass?
There is a lot of different foam out there available to us shapers, and the directions you pick are entirely up to you. However, it is nice to read and compare other’s experiences in deciding which direction you might take.