Can someone tell me what minimum size of compressor is needed for spray
painting? I would describe myself as a serious amateur and the machine
would be used for the occaisonal spray painting of laquer in a domestic
workshop.

The compressor requirements will vary with the gun you choose. Typically, a
110v 15 amp compressor with 20-30 gallon tank will be ok, and has the
advantage of being able to be used for other tools. Something like the PC
6025 or similar units will do the job (oil lube and cast iron cylinders are
much quieter).

Others have mentioned turbine units as an alternative to compressors. I've
done some research myself over the last few weeks, and the consensus seems
to be that turbine units can be a problem with lacquer due to their hot air
delivery, which continues to get hotter the more the unit is on. An air
compressor with an inline water/oil filter seems easier to deal with, and
the choice of non-turbine guns much greater.

Here's a few good online sources of information.

http://www.homesteadfinishing.com/ph...c261c0007baca6

http://www.targetcoatings.com/msgboard.html

http://www.woodweb.com/cgi-bin/forums/finishing.pl

http://www.woodfinishingsupplies.com/forum_frm.htm