spraying varnish topcoat

A small top feed auto touch-up gun would be my choice. HVLP (high volume low pressure) helps with overspray and gets into corners better.
I really like lacquer because of its ease of use, lack of waste, and repairability. I have found that with a top feeder using lacquer, complete cleanup can be postponed until a long period of inactivity. Big fan of Deft (brushing lacquer) because its the only lacquer available near here. Thin with lacquer thinner or acetone. Dries faster than varnish, but not as fast as the “standard” lacquer.
Have you considered just polishing your turnings? Use wet abrasives up to 600 or better dampened with water to temporarily swell the grain. The heat of sanding dries it out quickly and thoroughly when the final rub is applied with a clean cotton cloth. A bit of wax and you have a durable finish that you can control the gloss.
DanK

-- Dan Krager, Olney IL http://www.kragerwoodworking.weebly.com

Alistair, if you’re going with the varnish, you might thin it out a little with some mineral spirits or xylene, to make it spray better. I’d also try putting a little Japan dryer to speed up the dry time.

The method of polishing that Dan mentioned would also work good with this finish made into a wiping varnish, by adding 1 part each of pure tung oil, mineral spirits, and varnish as your final coating. You can add as much as 1/2 part Japan dryer, to speed up the dry.

-- Tim-- http://www.tmuli.com

Alistair I only use lacquer to spray turned pieces if it is needed and furniture I make other wise I use woodoc 10 available from phil irons in england. The woodoc is applied with a piece of old t shirt. Dan is spot on except check with your supplier about white spirits as this in some countries is turpentine for lacquer I use lacquer thinners. A small graity feed spray gun is ample for turned pieces a bigger gun for furniture pices. Regards Tamboti

-- Africa is not for sissies

Hi Alistair Merry Christmas to you and yours.
I’ve been spraying for about 40 years , The two links are for guns that are super buys and they would be great for what you want to use them for. The HF one is on sale a lot for around $20 or less and the little critter gun is great because it just uses Mason jars to spray from so you can just take it off and store the spare material.
I don’t know if you can get these in Scotland or not but if you could they are both good values and easy to use.

http://www.harborfreight.com/high-volume-low-pressure-gravity-feed-spray-gun-66222.html

http://www.amazon.com/Critter-Spray-Products-22032-Siphon/dp/B00006FRPJ

-- W James Brokenbourgh Custom furniture maker http://artisticwoodstudio.com/