I have just finished my decki and pergula using tight knot cedar. I have purchased Thompsons water seal with a pint of linseed oil added to the 5 gallons. Now......should I use a brush to apply or a sprayer? The pergula will be the hardest.
Brushing gives you better penetration. If you are going to use Thompson's though it doesn't really matter. Pour the stuff in the dirt to the side of the deck and you'll get about the same effect as brushing it on the deck, except your deck will look better. Linseed oil isn't really the proper product for what you are doing either. Get yourself a can of Sikkens SRD or at the very least Flood CWF-UV if you don't want any color to it.
Sikkens SRD is the way to go for sure, it will still need a washing and maintenance coat every 2-3 years. Brushing would be the easiest/best, and maybe a small 4" roller for the high stuff. Forget spraying, it will be too messy and easy to screw up. Please, please return the Thompsons, it does basically nothing and will ruin that beautiful cedar.
I really like Sikkens Log & Siding. It is a stain, sealer, and finish all in one product. I wouldnt put it on the deck floor, but it would be really nice on the Pergula. Check them out at www.nam.sikkens.com