The two part linear polyurethane coatings are also used extensively to coat aircraft so their spec. sheets will give you the weight usually in G/M**2. I weighs almost nothing. Abzco Nobel owns Awlgrip, Interlux, and several aerospace lines. Imron (Dupont) and Polthane (Sherwin Williams) are two other top brands. You can get great deals on e-bay for surplus paint. Since it's a thermosetting plastic like epoxy, there is essentially unlimited shelf life. For instance I bought a three gallon kit of Awlgrip II for $150 - this is $700 retail and enough paint to cover a bunch of catamarans. I have also purchased half gallon kits of Polane for $75 that includes 2 qts. of paint base, 1 qt. of catalyist, and 1 qt. of reducer.