Paint is one of the more difficult areas to get right. This is compounded by a couple of factors that make creating the perfect finish the hardest part of a seamless repair. This is how I do it.

 The first stage is preparing a base to work off. The excess glass and resin is removed, then the surface faired. I use Watertight epoxy based filler, manufactured by International. This applies beautifully to fair uneven areas, and fills the weave of the cloth in the underlying repair. An alternative to using this is to mix epoxy resin with glass bubbles until thick, then add a touch of silica to stop it sagging. I prefer using Watertight because of faster cure times and my epoxy pumps generally dispense too much resin for small areas.
  Deck faired
 For the initial sanding I use a random orbital sander. My favourite is manufactured by Festool (RO125), it’s a bit pricy, but provides amazing levels of control. One nice feature is the ability to switch between a course and a fine cuts, it really does let you go from 60 grit board chewer to 10000 grit and polish.
 At this stage I use 120 grit paper to get to a faired finish. To improve this further I apply some paint to act as a guide for the final sanding. The best option here is to use the same paint as your base coat, however when it’s cold the polyurethane I use takes so long to dry I use the same paint as the colour coat. This is sanded mostly off and maybe more filler is applied to remove any low spots. This stage is the most important for a great finish and any imperfections here will show in the finished result. To finish I sand with 220 then 400 grit to remove any sanding marks.
 The base coat is applied over this. I use International perfection base here as this is very durable and adheres to epoxy well. I use a fine artist brush to apply and tip off. The hardener is very nasty stuff and requires a full body suit and air fed mask to spray. Since the base coat can be sanded the brush is fine here.
 Mask! Base coat added
 The base coat is sanded wet with 400 paper. The fairness is checked again and any problems fixed at this stage. Any pin holds can be touched up with a glazing compound.
 Mask the area that needs painting. I use 3M fine line masking tape for the edge, then 3M blue scotch tape around. Finally, a mix of cheap tape and news paper to cover the surrounding area, go at least a meter or you'll get overspray - a rubber can be used to remove this if you get some(great tip from the boardlady!).
 Area masked to apply the graphics Finished Graphic
 For the colour coat I use Createx Autoborne paints. These are designed for custom paint jobs on cars but work well on boards. I spray them with a 0.5mm airbrush straight from the bottle. Mixing the correct colour can be a frustrating exercise. A very useful tool is a pantone colour guide. While these guides list the percentages to create a colour, ignore them! I've tried carefully mixing the paint with Gilson Pipettes, but it just doesn't work. My method for matching paint is to use the guide to tell you what colours you need, so for example, for a blue it may say blue 85, red 11, green 0. Start with blue then add a touch of red. I use cocktail sticks to add tiny drops of paint. Finally add black or white to get the correct tint. Bit of a faff!
 Pantone colour guide are expensive new, but can be had off eBay for £20.
For the areas that are not non-slip the autoborne paints need to have a protective layer. Polyurethane finish is the best bet. For non slip areas I use International Perfection varnish. It is very clear and very tough. I apply this with a fine artist brush, then sprinkle fine anti-slip on. A pair of tights over the end of a cup makes a great applicator (tip from Jono Dunn). If the finish is plain white the non-slip can be applied directly to this. I try and match the existing finish of the board.
Colour coat applied Non-slip applied
The final finish can be buffed to a shine, or to a fine matt depending upon the existing finish. Board bottoms should be matt for the best performance.