I just picked a very nice H-I Tonka Queen bamboo rod.
The reel seat has been replaced with a U/L with a very light blonde wood insert.
I wish to sand, stain, and varnish this insert to a nice cherrywood finish.
My only question is how to avoid picking up air particles while the varnish dries?
I will be using Ace Spar Varnish.
What are you asking? Are you concerned dust from the air getting to the seal while the varnish is drying, and making the finish to have irregular spots, or are you concerned about bubbles in the finish?
With your application it would be very difficult to change color on a installed mortised real seat. Unless you wish to do the risky option of removing the whole seat and installing another I would let it be. However if I was compelled to try this with the seat on, I would take my time hand wet sanding the wood coating down. Probably 400-600 grit paper. Take your time so as not to damage the contour and threads. When the wood is prerpared I would try using very light coats of a penetrating stain. Then finish with a poly spar. I would also do all of the work under magification. Be sure to tape off certain parts. In addition: you can purchase sanding sticks at hobby shops. These would enble you to get into tight areas and also sand the “shelf” on the motise.
Under the normal making of reel seats:
I have the seat(s) on a all thread or metal rod. So the seat is held loosly by nuts or washers. I varish light coats and sand in between coating. To prevent bubbles do not shake can before use. Stir lightly and do not allow too much run off from the mixing stick. The way I found to keep dust and othercrap off of the seat is to varish inside of a plastic storage container. I appy a thin seal, then close the container tight. The rod/all tread is on stands. I will open occasionally to turn the seat. However, usually I have a dryer type motor turning the seat(s). I found this method vertually eliminates crap in the coat. Again more light coats is better. You can find a good assortment of plastic storage containers at Lowes or the Depot.
Dust from the air is not a problem. It is the dust you pick up on your brush that gets imbedded in the varnish. You can use 1000 or1200 grit wet and dry finishing paper wrapped on a craft stick and lubricated with some mineral spirits to get rid of any dust specs. Polish with some Turtle Wax scratch and swirl remover. It is easier to polish than it is to mess around trying to be dust free. The Ace Hardware spar is what I use on all of my rods and reel seats. It is pretty forgiving stuff.
Your real problem is going to be getting a good stain job on a reel seat that is already assembled.
Myself I prefer to apply rod varnish by hand after washing my hands really good and letting them air dry that way I know that i wont be getting dust in the finnish from using a brush or other type of applicator…