Spraying coach enamel – the basics.
To apply coach enamel by spraying it will need thinning by around 5-10%. There is no hard and fast rule as a number of factors come into play, such as temperature of the paint, the air temperature, size of nozzle and spraying air pressure.
For spraying Coach Enamel which is fairly thin when diluted with thinner you would ideally use a No 14 nozzle (usually supplied as standard with the gun), but you can go up to a No 16 Nozzle. Increasing or decreasing the quantity of thinners used will enable an even spray pattern. The larger the nozzle will encourage more paint to be applied and open up an increased risk of runs and sagging.
From a practical point of view, for the first spray of the job, fill the paint reservoir half full and add a small amount of thinner, mix well and spray using around 40psi onto a test piece.
If the result looks uneven and ‘bitty’ then you have not quite thinned it enough, a side effect will probably be very little spray dust coming from the gun as well. To rectify, add a little more thinner, mix well and try again.
If the result is a good even coat with an even coverage you have achieved the result you need for a good job.
However, if you have used too much thinner, you will find the paint on the test piece could result in sagging immediately, or the paint looking translucent and very thin. As a secondary effect you may also get an excess of spray dust.
A tip worthy of thought is to start with the paint reservoir being half full so that you can either add more paint or thinner, whichever is deficient. Once you are familiar with what thinning you need, for the rest of the task, you can fill the reservoir to a level you are happy with. This thinning can vary day by day.
The only other thing which is worthwhile mentioning is try not to overspray a previously sprayed area (such as edges or fiddly areas) as this could create a thick area of coating which may result in sagging (a long run).