John assuming you are using Acrylics Vallejo Lifecolor etc. Not using enamels so I can not give an answer on that type of paint. Also my experience is with Acrylic water based but using the manufacturers own thinners. I would not use water as it has its in built tension whereas manufacturers thinners does not. John if you could give the paint you are using, pressure you are using plus if you are thinning the paint and what thinners that would be of a great help.
Can the supplier of the
airbrush not tell you the size of the needle/nozzle. If on Amazon you can pose the question. On Ebay I am not sure.
For general work spraying in large areas ie a fuselage on a 1/72 or 1/48 I use an Iwata fitted with a .35 needle/nozzle Also I have used and still use for varnish a .4 on a Harder and Steenbeck. For me these seem perfect for this work.
If you are getting a H and S they are great airbrushes and I used them for about 4 year. They on average have the option of .18, .2, .4 and .6 needle/ nozzle sizes. Having recently converted to Iwata I find, for me, they give a slightly better finish but they are" the very devil to take apart and clean". H & S are very simple to take apart. My record was 4 minutes take completely apart deep clean each part and put together. Iwata not timed but it compares to using a garden lawn mower on the Oval cricket ground.
I do not, sorry Steve, agree on the fine detailing. For detail fine shading weathering I have used recently and extensively an Iwata with a .2 needle/nozzle for which gives me greater control. I have tried my .35 for detailed work and though good there is much more paint control with the .2 which gives a smaller cone, about two thirds of a .35, plus the amount of paint pushed out is smaller giving further control.
If you are using acrylics then it is worth trying the Vallejo Flow Improver. Not used it yet mainly as I have it but cannot find it :rolleyes:. But have heard good reports.
Laurie