First time im using an airbrush or should i say first time im making a real model ( now am taking the trouble to trim the sprues properly, fill gaps, sand, mask and try weathering) and have had several problems and questions:
1)Can i spray acrylics directly onto plastic without using a primer.
2)What ratio of paint to thinner do i use for spraying
3)Can window cleaner be used as a thinner, without water.
1)Paint keeps drying on the needle or doesnt dry at all, even on the model for a long time!!!
2)Airbrush alternates between producing a fine mist, blobs of paint or just air,sprays clean water without any problems.
[*]That's not as easy to answer as it seems You really need to develop a bit of a feeling for this I'd recommend starting at about a 50/50 mix, and doing a little test spraying (I usually do this on the newspaper that I use to cover the area where I spray). If the airbrush stutters or spatters droplets, add more thinner, while if the paint runs, you need to add more paint to the cup. Adjust the mixture until it does neither, then it should be at the right thickness. After a few times, you'll get the proportions right (most of the time) first time round However, you will find that using different types of paint and/or thinner basically means you have to start all over again trying to find the best proportions, as (for example) acrylic paint + water will need different ones than acrylic paint + the manufacturer's thinner
[*]If it's water- and/or alcohol-based, I think so. I usually spray with windscreen wiper fluid these days, and don't add anything else to the paint.[/list]
As for your problems, if paint dries on the needle it's probably too thick, but if it doesn't seem to dry at all, it's too thin. Like I said, this is mostly a matter of experience. The other problem seems to be basically the same blobs of paint means it's too thick, for example. If the airbrush does both of these at more or less the same time, my thought is that you didn't mix your paint and thinner well enough. Best to stir it thoroughly using a flat (not round) stick, and make sure you scrape the bottom of the paint cup as you do so, else there will be a layer of thick paint there that will probably get drawn into the airbrush first.