Seam Sealing

The tent should come with the seam sealer and instructions. You seam seal the INSIDE of the fly. The reason that MacPac require you to seam seal the tents is that there was an issue with the heat sealing process weakening the fabric. It is not cost effective to manually seal seal the tents in the factory so MacPac decided to ask the customer to do it. It only needs to be done once.

I'm currently unfamiliar with the brand of seam seal they are providing. Seam grip by Mc Nett has been universally reliable for many years. Information which is not usually recorded on the smaller tubes includes keeping the tube in the fridge between uses to avoid it hardening. Put the brush in water to limit contact with air and reduce the speed with which it hardens. Tape the area adjacent to the seams to achieve neatness and limit the spread of adhesive. Do sections at a time and allow to dry. When fully cured sprinkle talc on the seams to eliminate the seams sticking to anything when the tent is packed up for awhile. Good luck

Here's what the MacPac site has to say http://www.macpac.co.nz/product-support/tents#seam