*Disclaimer if you have a super valuable guitar, or you're the type that will blame me if anything goes wrong, DON'T DO THIS. This is more for the guys with duct tape on the guitar straps, and old beer rusting their pickups.
*Don't do this if you have a nitrocellulose painted neck (many of the expensive fender recreations have this). Personally, I've done it on nitro, and had no probs, but nitro can be touchy, so do at your own risk. And my official word is DON'T DO IT.
Got a neck that jams up when you get sweaty? One that feels more like a basket ball court floor, than a smooth buttery neck? Yo can do this whole mod, without even taking the strings off and end up with a smooth neck for your non-precious, playing guitar.
Finish in 20 min.
1) get some rub on polyurethane. Any home depot, Do-it-Center, etc, will have it. Using this means you can use a rag, don't have to spray anything, and can do it on the kitchen table and make pretty much no mess. It'll be in the wood staining section of the hardware store. You want wipe on (rub on) polyurethane, matte finish. Don't get any with stains and other crap in them, just the simple matte rub on, and get the smallest container possible.
2) Get some extra fine "waterproof" sand-paper. Some regular hardware stores have them, otherwise, any auto-parts store will have. It's in the section for doing touch-ups on paint. You want to get at least to about 400 grit, preferably even 600grit. One sheet of each will work.
3)Start with the four hundred. give the neck a nice sanding, This shouldn't be precise. it should be more natural feeling. Or a "relic" type of sanding that is only on the parts of the neck most heavily used. Hold the sand paper in your palm, and sand the neck back just enough to roughen it up and get that top layer of poly off... But its ok if some is left there too. After a few min, the neck will already start to feel more slick and comfy. You can stop anytime you feel like it. We are not refinishing the neck in a proper way, we're just intentionally scuffing it up and opening up the raw wood a hair.
4) optional repeat with 600 grit for super smooth. I am good with 400, because it just feels nice to me. 600 will be slicker.
Now clean up all the sanding crap. Clean off all the dust, clean off your table, wipe the neck down with either a slightly damp rag, or some paper towels with either naphta or some rubbing alcohol.
Nothing crazy, just a quick wipedown.
Now with a clean table, comes the easy part.
Make sure the can of poly is mixed properly.
put a little on the rag, and apply a nice thin coat.
Let that have 5 or 10 min to dry and do it again. You're just getting a spot about the size of a quarter on the rag, and evenly covering all that you sanded.
It will barely look any different.
At that point, let it dry for a bit (it'll dry fast because we've applied such a tiny thin layer or two).
Your neck should feel much smoother and less susceptible to the sticky neck syndrome that can happen when hands get sweaty.
Hope you enjoy it!