nail hole fillers are usually diamond hard and unstainable, mareted as stainable, but brittle and ugly or precolored but never harden- in short, I have yet to find an exterior wood filler I liked.

Mill glaze is effectively a generic term which can mean one of two things. Firstly, it can refer to a thick oily wax that is used as a lubricant for the saws.

the second definition is somewhat more complicated. The friction of the saw causes the dry wood to heat up. this sudden increase in temperature causes the natural oils in the wood to seep out leaving a thin nearly invisible coating on the wood.

either way it is ALWAYS a god idea to clean your wood. you have no idea what happens to the boards you will be using from the time it leaves the mill to the time it gets to your house. now, they recommended TSP? that seems odd to me. I personally would use something that contained a chemical called oxallic acid. generally, theyre labeled as "deck brighteners," and id recommend going to a paint store for that because I doubt the lovely employees at your local box store would have the slightest inkling as to what that means. power washing is always a good idea before coating anything outside. If you've never done it before, my advise to you is to move quickly, if youre power washer is too strong and you linger on a particular section for too long the stream WILL fray and splinter the wood. as far as the back end grain and joints? you could very well leave them alone. coat the back with the stain for cosmetic's sake, but generally you want some open area to allow the wood to breath, release moisture and prevent the wood from warping...any questions? lol