How Green is my foam?
Monday, July 2nd, 2007Can you really build a ‘green’ board? Not completely (unless you want to go back to wood and shellac), but it is possible to mitigate the impact of board making materials as this article from Home Blown USA outlines…
Here’s an excerpt:
“To go “green” is everywhere, even in our world of surfboards. While a surfboard is a composite structure that is made primarily from petroleum based products and hardly could be called “green”, there are a few steps in the right direction. Any step forward is a good one and should be applauded but the truth is surfboards have a long way to go.To understand this, it is important to understand a bit about the materials now used and then more importantly some terminology.
The standard issue surfboard for the past 47 or so years has been made from polyurethane foam (PU) and polyester resin with a fiberglass cloth. PU foam is petroleum based as is the polyester resin and although fiberglass starts life as a clean natural product, to make it workable it is run through very toxic chemical baths. No “green” here.
Epoxy boards have been around nearly as long as the above PU boards but have only recently made big inroads. These are made with polystyrene foam and there are two types. The beaded ice chest or coffee cup style is expanded beads (EPS) or a version that looks more similar to PU foam which is extruded (EXP). Both of these still use the fiberglass like above but the resin used is epoxy resin – hence the name.
These two versions of surfboards still make up the majority of surfboards available. Variations on the idea such as the variety of molded boards now in acceptance still use the materials listed above.
So where is the green part? None of the foams above are green in any way and in fact some are quite bad to both the local environment because of the VOCs released and to the workers for the somewhat deadly chemical exposure. To explain further lets look at the above materials again…”
click here for the rest of the article
And, making the case fro MDI PU material, there is this article on www.wetsand.com
Excerpt:
Right now, thousands of blanks are streaming into the U.S. from factories around the world – South Africa, Brazil, Argentina, Spain, Australia, China, and the UK. The vast majority of these manufacturers use TDI in their blanks. In addition to the various tolls exacted by this known carcinogen, it seems to me that shipping containers of a lightweight product like foam around the world is wasteful and just doesn’t make sense. Having the cores of our supposedly ‘green’-oriented surfcraft hauled all over the planet by the shipping container network is hardly ‘green’ thinking. Shipping just the raw materials needed to make a foam blank is at least 18 times more fuel-efficient than shipping the whole blank.
However, there is another type of polyurethane foam now available, one using MDI (methylene di-phenyl di-isocyanate) instead of TDI. Even Gordon Clark was experimenting with MDI-based foam before he called it quits. The main health hazard associated with isocyanates stems from the inhalation of aerosols, which can cause respiratory problems. When molding rigid foams such as surfboard blanks, there is the additional hazard of partially cured foam dust being released into the air during the de-molding process. MDI, with a vapor pressure of some 2500 times less than that of TDI at ambient temperatures, is by far the least hazardous of the commonly available isocyanates. This means that the molding pressure is much less and, therefore, a part out of the mold is more fully cured. According to NIOSH (National Institute for Occupational Safety and Health), studies have demonstrated that commercial grade TDI is carcinogenic in rats and mice and therefore TDI is a substance “which may be reasonably anticipated to a carcinogen.”
A modern MDI-based blank plant, such as Homeblown U.S. in San Diego, relies on a computer-controlled pouring machine that ensures the resins are delivered precisely in the correct amount to the mold’s extremities. This results in an astonishing consistency – with minimal waste – in blank manufacture. Air voids and pour marks are eliminated and a consistent density and hardness is achieved throughout the blank. The resulting MDI-based foam blanks are 15% to 25% stronger in compression strength than any other TDI foam of comparable density, according to the results of independent testing. MDI-based foams are rated ten times more waterproof than those based on TDI, and so suffer much less saturation when dinged. The consistent density throughout allows for very clean CNC shaping with no concerns about softer foam toward the center of the blank. The smaller cell structure is excellent for color work and absorbs less resin, resulting in lighter and stronger boards overall. While some builders might worry about about delamination, this isn’t seen as a factor because delamination typically occurs when foam separates from itself – which is far less likely with MDI-based foam.