Working with Surfblanks polyurethane foam surfboard blanks.
Description: Closed cell, rigid polyurethane foam.
More: A fully reacted polymer composed of carbon dioxide blown polyalcohols and Toluene Di Isocyanate.
The components are fluids to begin with but transform to a dry, dusty skinned, rigid plastic during thirty minutes of reaction. The skin is then post cured (within 24 hours) to form a firm, shapeable surface.
Once cured, Surfblanks foam is impervious to attack from solvents.
Toluene Di Isocyanate in liquid form is classified as Toxic 6. Initially water reacts with the TDI to produce carbon dioxide which blows the formulated ingredients to a foamed plastic. The balance of the TDI is reacted to solid form by the water (urea) and the polyol (urethane linkages) which creates the polymer back bone. The TDI is formulated to be in excess of the polyol to provide dimensional stability for the finished rigid foam.
Burning Surfblanks foam will create poisonous vapour. Likewise heating Surfblanks foam (or any other) to elevated temperatures with dull cutting tools in an enclosed environment is highly undesirable. Smoking a cigarette in a shaping room is considered madness! Heat or fire will release carbon monoxide, oxides of nitrogen and hydrogen cyanide.
Comfort: There should be a flow of fresh air present while the shaper is performing major cutting of the foam. Ideally, an overhead fan should blow down on the operator providing that air. That same fan will remove dust from the shapers face level. Some shapers will use a battery driven, air fed, full face mask. The added benefit is that the eyes are protected from the gritty foam dust.
Respiratory protection: For many decades a double strapped paper mask (nuisance dust mask) has been accepted as the minimum requirement while shaping surfboard foam. Fine foam dust will not pass through the paper mask. This reduces the risk of throat and lung irritation from the abrasive, brittle particles. These same particles are considered to be too large to affect the shaper’s lungs.
Over the four plus decades that the modern surfboard industry has been functioning, shapers have been found to be the healthiest of manual workers. Partly this is due to the fact that most are keen surfers, and partly it is due to the physical exertion required to shape a blank. Occupational health lung function tests (Australia) have confirmed no decrease in air volume capacity over a shaper’s working day.
See MSDS in Downloads at the bottom of this page.
Working with Surfblanks fiber glass cloth.
Inhalation of fiber glass particals can be avoided by wearing a double strap paper mask (industry standard). Cut or ground (sanded) cloth particals are considered too large to impact the lung wall, however irritation to any part of the body caused by partical contact can be compared to ground glass (bottle glass) being rubbed in to the eye or skin.
Most glassers will use long sleeves and pants to avoid skin contact. Cheap paper suits are also employed. Fiber glass particals float in air so air extraction through a filter in the workplace is highly desirable.
The chemicals used to treat the yarn in the cloth during its manufacture are hazardous, however these chemicals don’t come into play while being used with polyester resin in the glassing process.
See MSDS in Downloads at the bottom of this page.
Working with Surfblanks polyester surfboard resin.
Inhalation of styrene monomer vapour is to be avoided. A half face mask fitted with charcoal filters is the industry standard.
Wear chemical resistant gloves (eg nitrile) and do not work in a confined space. Bare hand glassing followed by an acetone wash is an absolute no no. Acetone passes straight through the skin into the blood stream and through the vital organs.
Breathing enough styrene monomer induces a state of lightheadedness similar to alcohol intake. Styrene was long suspected of causing sterility in males but warnings for this have been toned down.
Exposure limits (no mask) for styrene monomer are currently 50 ppm.
Ideally a glasser’s work space would be air extracted so that there is always removal of contaminated air replaced with an inflow of fresh air.
Polyester resin is temperature sensitive, it wont crosslink under 15c and process time is lost over 30c. Excess MEKP cannot be absorbed by the promotors in cold weather so yellowing and poor polymer strength will result. Insufficient MEKP in hot weather has a similar effect in that crosslinking is poor and it may require two weeks or more of moderate day temperatures before any kind of a reasonable cure is achieved.
How many times has a surfer brought a recently made board to the blank maker complaining of softness when in reality the glass job had never cured before the board was ridden? The glass job has firmed up after the damage is done so the rider can’t see the logic.
Ideally polyester resin would be catalysed at 1 – 2% (promotor equivalent) and used in a room where the temperature was held at 25c. Problem is, how do you keep temperature and exchange air at the same time (throughout the seasons)?
Alternatively in cold climates a warm/hot enclosure can be created so that the glass job is done in flowing cold air, then placed in the enclosure and quickly heat gelled/cured. An electric oil heater (relatively safe) works well in this situation, along with a plywood closet (full length doors) wall racks and a top vapour vent.
Better still, use UV cure resin, process in moving air (any temp) then run the job through a light tunnel/chamber and in minutes it’s all over. If you have glassing stands next to a door that accesses the outside, apply the resin then walk the job out into sunlight. Four minutes is about average for a good UV resin. As soon as the finished board sees sunlight on the beach, curing continues!
Polyester resin is manufactured by reacting maleic, pthalic and propylene glycol in a kettle until a linked, long chain backbone is formed. The product is then dissolved in styrene monomer which it later crosslinks with when metal salts and amines react with an initiator (MEKP) to generate heat. While the backbone ingredients are hazardous prior to the kettle reaction it is the styrene that generates the most concern.
Those of us who work in the industry may appreciate a hint of styrene in the air, but the faintest whiff will freak the neighbours out in a residential environment.
Seal containers when not in use and store in a cool place. Shelf life for uncatalysed resin varies from three months to two years depending on storage temperature. Polyester resin is classed Flammable 3, so avoid storage near an ignition source. Local authorities may require flameproof lighting and switch fittings in the work place.
See MSDS in Downloads at the bottom of this page.
Working with MEKP.
Methyl ethyl ketone peroxide (usually 40% strength in a plasticiser) is a free radical initiator, used to trigger heating and then crosslinking in polyester resins containing styrene monomer. The MEKP reacts with the metal salt and amine promotors that are premixed in the polyester, the resin heats, then thickens and begins to solidify. Very small quantities of MEKP are required in production, however great care has to be exercised in handling this product. MEKP is packaged in resealable plastic containers and needs to be kept well isolated from all other products. Since there is always the chance of leakage even when unattended, a container of MEKP is best stored in another oversized plastic container.
MEKP is corrosive and reacts with eye and skin tissue immediately. One small splash can cause an agonizing burning sensation. Intense washing with water will dilute the MEKP and slow its effect. Splashes on clothing eventually make their way to the skin, so great care needs to be taken. Most pofessional glassers will use a sealed, plastic dispensing bottle with a top mounted measuring cylinder that is internally fed by a fine tube from the bottle below. Surfblanks can provide this type of MEKP dispenser.
See MSDS in Downloads at the bottom of this page
Working with Acetone.
Acetone is a very aggressive solvent for polyester resin. Washing brushes and squeegees after glassing is best done in acetone. Small makers wil resort to other ‘greener’ methods of wash up, but when all is said and done acetone does it fastest and best. Used or ‘dirty’ acetone is often recycled through a small condensing unit.
Highly inflammable and highly evapourative, acetone needs to be stored and used carefully! Usually plastic containers with loose lids, placed in larger plastic containers to catch splash and spill are the way to go. Pressure can build quickly with small temperature changes so cool, ventillated storage must be considered.
Observe what a small amount of acetone will do to the paint on a metal pail or drum and you can imagine how fast it will penetrate human skin. When resin does need to be removed from skin with acetone, use a cloth dampened with acetone so that minimal contact is made.