A ‘Bow Pen’ (shown on left in pic' below) available from art or technical drawing equipment suppliers is ideal for
filling in paint/emamel holes; they are also known by other names, our 'Jurek' will be able to point you in the right direction as well.
What makes them so good is that the hole is filled in, where as painting over a chip still effectively leaves a hole, your thinking of "thinking Humbrol " is perfect for these pens as well.
The Chainstay can be covered with chainstay protector or normal electrical tape, the latter is both cheaper and can be cut to just the right size to cover the desired area:
Alternatively a single colour enamel from someone like Vaz finishes would be ideal, a plain enamel so that it will be easier to 'touch up later'; I have listed him below with a couple of others that may be useful.
Vaz Cycle Finishes: - 020 8852 0711,
Lewisham,
London SE13, for a plain enamel he is good.
Colour Tech: - 01322 555549.
OLD FARM BUILDINGS
MAIDEN LANE
DARTFORD
DA1 4LX.
Probably slightly better than Vaz at the more intricate finishes; although I have not used Vaz for a few years, he may be as good now. He will send a frame by carrier if need be.
www.daveyatescycles.co.uk - 01526 343322 (During office hours only please!)
Ivy House Farm
Hawthorn Hill
Coningsby
Lincolnshire
LN4 4UW, very good and will send frame by carrier if need be, here is an example;
My Pearson Bike, (Dave Yates built back when I was there)Paul_Smithwww.corridori.co.uk