I am getting ready for my next glassing session, and part of my pregame is seeing if I have enough resin, cloth, etc...
Are people using spreadsheets at all to calculate the amount of resin needed for their lams? Or are people good with rules of thumb such as 2oz per linear foot of board per layer of lams and 1oz per linear foot of hot/gloss coats?
I am using 6oz E-glass and Resin Research epoxy, 1 layer up top with a 3/4 length deck patch, 1 layer down low with a 1/4 length tail patch. The board is 8' x 23' x 3.5" . With the thumb rule I get:
16oz top + 12 oz deck patch,16oz bottom + 4 oz tail patch+16 oz hot coat+16 oz gloss= 80oz = 5 pounds= 2.2 kg or so. My spreadsheet calculating all by weight per unit of area comes close to this, using a resin to cloth ratio of 1.2 to 1 by weight. The jug of resin still weighs 8 pounds so I am plenty good to go without reordering.
I can hear Stingray saying 'it's a surfamaboard, it's epoxy, just mix some more'...so true. I would still like to have an organized way of starting out close, provided I can feed it a good set of numbers like area or weight of cloth per operation. Some of the fiberglassing vendors have online calculators, but they seem to be aimed a bit more at selling rolls of cloth and gallons of resin than figuring out how much to put in the bucket for this lam or that coat.
1. Is the rule of thumb fluid ounces volume? In that case I am probably off a little by weight.
2. I have heard it said that epoxy lams take less resin than poly lams. Is this really true in simple hand layups like this? Is there a finite number that goes with this?
3. If such a spreadsheet was deemed accurate enough, could it be placed on Sways as a document or coded into an applet for public use?