The preferred sealer for A/S appears to be Alcoa Gutter Seal. It seems to be hard to find and suggest you call Alocoa Alumimun Co., 1-800-621-7466. to find a distributor in your area. It come in silver and gray color. I haven't been able to find it in Texas, New Mexico, or Arizona unless I buy a case of 24 tubes at about $88.00. Another chalk I have seen recommended and am using is called Ten-X, made by H.B. Fuller Co, Minneapolis, MN. It comes in clear, white, aluminim, and architectural bronze in 5 oz types, quarts and gals. I got my tube from our local Holiday RV, who also is an Airstream distributor. They ordered it in for me. I haven't used it on any seams but on gaps in the lower rub rail and I haven't had it in use long enough to see how it holds up. It is fairly thick and I am not sure how well it "wicks" into the seams the way Alcoa Gutter Seal is supposed to do.

From all indications Ten-X does not contain silicone. Alcoa Gutter seal is apparently fairly thin and I have heard of one owner who used a hypodermic needle with success.

Roy