On 11/11/2015 11:52 AM, Howard Audsley wrote: ...
I know polyester is less expensive, which is why they use it to do the initial laminations of boats, but I've only used epoxy for repairs.
Historically, polyester resin (and the usual MEKP catalys) is nasty nasty toxic. Skin contact, vapor, everything; you'd want to wear tyvek suit, serious gloves, and a serious respirator rated for the nasty vapors polyester resin puts off. I see there are some "low VOC" marketed products now; here's the MSDS for what appears to be a major brand for surfboards: http://solarez.com/product_images/msds/MSDS_Solarez.pdf ...see section VI and IX for 'health hazard data' and 'special protection information' - sounds like it's still pretty nasty, even if "low VOC." Generally polyester is cheaper, more prone to linear shrinkage, and way more toxic to work with; epoxy is more expensive, less prone to any shrinkage, and most modern quality brands (West, Sys. III, etc.) are essentially zero VOC and (relatively!) safe to work with (you don't want it on you, inside or out, but respirator not needed, etc.). Either one will get hot enough to cause damage when curing if you're using it as a space-filler and pour too much volume at once. There may be some very sloooow cure flavors available for those purposes. You could presumably use filler material (microballons, etc.) in your batches that are just for filling extra space and cut down on amount of resin needed for fill. cheers, John S. -- John Schinnerer - M.A., Whole Systems Design -------------------------------------------- - Eco-Living - Whole Systems Design Services People - Place - Learning - Integration john@eco-living.net - 510.982.1334 http://eco-living.net http://sociocracyconsulting.com