Airbrushing Rough Finish

[fishplanebeer]

I'm still getting the  hang of my airbrush and generally things work out OK but on my current build the matt enamel paint left a rough texture akin to sand paper so wonder what I'm doing wrong as the airbrush, an Iwata Eclipse, is totally clean and fully functional so no problems there.

 

I'm thinking perhaps the psi was too low or the paint too thick but I think I read somewhere (?) that it can be caused by spraying too far away from the model so that some of the paint begins to dry before it hits the plastic? The issue is I'm still quite nervous about getting up too close to the subject in case I end up with runs.

 

Any advice/tips greatly appreciated,

 

Regards

Colin.

 

 

[Rabbit Leader]

Colin, 

My initial thoughts are that your compressor's pressure may be set too high, although this may be due to the paint being too think so a high pressure is required for any paint to spray out.

Airbrushing takes time to master and you know when you get there when it all 'feels' right, so try thinning the paint and reducing the pressure a little. Paints behave differently as well. what brand of paint and thinners are you using? 

Cheers.. Dave  

[dnl42]

This can definitely be caused by holding the airbrush too far from the model surface. Watch the paint as it hits the surface, it should be wet. Spray at 0.25 in to 1.75 in (5 to 45 mm).

 

Here's a longer write-up of how I apply paint.

 

HTH

--

dnl

[dogsbody]

What I learned last year during my first airbrushing attempt, using Tamiya and G-S acrylics, is to use about 15 psi and the paint thinned about 45% paint to about 55% thinner. I also added a few drops of retarder to prevent tip drying. The results were way better than I expected, but not up to the results you see from the masters on this forum.

 

 

 

Chris

[Ray_W]

I'm with @dnl42. Spraying too far from the surface. As said, importantly, ensure the paint is hitting the surface wet but not flooding. Also watch dry paint over spray does not get caught in an area. For example spraying a wing and overspray getting caught in the wing root. Get in close and less issues.  

 

Having said that, in my experience, the correct thinning ratio is the most critical factor. You also know when you have this wrong because the airbrush makes a very faint crackle noise. Thinned right - smooth, no noise.

 

Pressure is less critical assuming you're working in our normal range 8 - 20 psi range. I set pressure depending on how much coverage and distance I want to work with from the surface. With the right thinning ratio, the pressure setting and most spray problems disappear. I suggest thin it a bit more, check pressure is reasonable, say 12-15 psi and go in closer. 

 

Ray

[modelmaker]

I'm no master modeller but I have been airbrushing for 30+ years, and if I've learned one thing it is practice practice practice. I am CONSTANTLY learning every time I paint. I think a lot of us are the same. I completely agree that spraying from too far away may cause the paint to go on 'dry', and depending on how you thin the paint may be an issue too. I use enamels mostly, and I  find that slightly thinner may be better if you want to hold off a little but if I have to get in really close it may then be TOO thin and watery. Enamels can be different to acrylics, and I know many swear by them but I personally get on better with the old fashioned stuff. Practice!  Every time you use it can be different too. Practice!

[fishplanebeer]

I was using Xtracolor 'Tyre Black' (which seems quite coarse anyway) thinned with Phoenix Precision thinners at a ratio of around 60% paint to 40% thinners and with an indicated psi of around 14. I was also spraying from a distance of around 6 inches (150mm) and this worked fine with the Colourcoats and Humbrol paints I'd used for the splinter camouflage so I'm wondering if the paint itself could also be part of the problem perhaps?

 

I'm also thinking that the ambient temperature being where it is as the moment may have caused the paint to dry more quickly in the air than usual as I applied the splinter camouflage (Colourcoats & Humbrol) in cooler air before the very recent heat wave.

 

Regards

Colin.

[dnl42]

2 hours ago, fishplanebeer said:

I was also spraying from a distance of around 6 inches (150mm)

That is a HUGE distance for an airbrush. May be perfectly fine for a rattle can that blows a massive volume of paint out, but not for an airbrush.

[modelmaker]

1 hour ago, dnl42 said:

That is a HUGE distance for an airbrush. May be perfectly fine for a rattle can that blows a massive volume of paint out, but not for an airbrush.

Good point!  

[Jamie @ Sovereign Hobbies]

Hi Colin, I'd normally be working at 1/6th the distance, maybe 1/2 if applying a final clearcoat over the full area. It sounds like your paint is getting too much time to flash off in flight.

[fishplanebeer]

It seems I need to be much braver and smarter in the use of my airbrush and get much closer. It's a bit of psychological hurdle to overcome as when I first used an airbrush many years ago I ended up flooding the model with paint by getting close (2 inches-ish) so when I returned to the hobby late last year I decided to spray further away to compensate.

 

However it seems the correct way of preventing such flooding is to use a sensible psi of around 12-14 psi and correctly thinned paint, not too thin or thick, and I'll then get the correct finish as well, so thank you for this insight and advice.

 

Next job on my 72nd scale Do217E, having rubbed down the rough finish with Alclad 'Micro-mesh' 3600 grade, is to apply a satin varnish prior to using a Flory's wash and then some oil paints weathering, so wish me luck as I've never used Flory's or oils in this way before.

 

Regards

Colin.

 

Ps. by the way I've found the Alclad 'Micromesh' sanding sheets  (bought years ago) to be excellent for fine sanding and finishing work

[Jamie @ Sovereign Hobbies]

Assuming your airbrush is dual action of some description the trick is finding that point where your needle valve is just starting to flow paint. In some respects it's similar to a learner driver finding the biting point of a car's clutch.

 

There's always a tendency I think to do as you are and I did likewise - don't thin the paint much as you want to cover. Turn up the pressure to force it to flow. Flood the model with the airbrush needle opened all the way then increase the distance from the target to disperse the deluge of paint to avoid flooding.

 

You're absolutely correct that it's a mental hurdle. If you have a model that's abandoned or you don't mind practising on though, try thinning more (go 50/50 paint to thinners if using my paint), crank your pressure down to 15psi static (pressure will drop a 1-3psi when flowing usually) and practise finding that needle opening where the paint just starts flowing and play about. Using a paint mule makes it a safe environment - you can't screw up and nothing matters

[Ray_W]

35 minutes ago, Jamie @ Sovereign Hobbies said:

In some respects it's similar to a learner driver finding the biting point of a car's clutch.

Read this and thought the whole post what great advice.

 

6 hours ago, fishplanebeer said:

It seems I need to be much braver and smarter in the use of my airbrush and get much closer.

 

Practice lines, dots and squiggles. You can do this on a bit of card, paper or your paint mule. It is amazing how quickly you pick up the type of feel that Jamie was talking about.  You will know how far from the surface you need to be and can really watch the paint laying down making sure not too dry or wet. By the way, I keep practicing during a paint job getting that paint start point and paint flow feel,. Usually on the most convenient item - my gloved hand. Very useful for squiggles and mottles like yesterday's job.

 

 

 

Ray

[modelmaker]

If this helps?

When I came back to the hobby after all those years I discovered I still couldn't brush paint. Couldn't in 1970, still couldn't in 1990.

A mate FORCED me to buy one of those£10 glass jars with a plastic handle and a nozzle on the front. Revaluation. Painted bicycle frames, model cars etc beautifully, but had limitations!

Bought a Paasche single action, loved it. Would put down beautiful coats of paint, large single coat coverings in one go, like a much better version of the first glass jar. Loved it, but double action sounded even better. 

My wife spent a FORTUNE on an Aztec. It had so much control, and would paint a beautiful coat of paint, one covering etc, like a much much better version of previous ones. I've got models with complicated squiggly camo (Macchi 205 etc) in '72nd I'd struggle to do now. You could just go, perfect every time. BUT after a while I had to repeatedly take them back to the art shop from whence it came (remember shops?) because after a while they stopped working properly. Lifelong guarantee, no problem UNTIL one day when they now had a 12 month guarantee, which killed them. I know at least one world class modeller who still uses them I believe?

I then went conventional metal, double action, 0.2ish nozzle, with which you CAN with skill (apparently), practice, and the black art of mixture and pressure balance paint astonishing details, touch upp tiny little areas, and do many things that after all the years I'm better at but still not a patch on what I often see here. I struggle still to paint a model in 'one coat' like I used to be able to, instead have to paint a larger model in lighter coats, building finishes up, which is quite possibly what I ought to be doing anyway, but it's just different to what I found before. Even with a 0.5 nozzle I don't find I can pass larger volumes, or at least 'heavier' mix ratios like before. I have a cheapo single action for that, I just find it easier. I'm no master modeller!  It works .

One thing, I don't think there are actually 'correct' pressures or mix ratios, every time is different. Every airbrush is different. Every type of paint or even tin of the same identical paint is different. Every reference I may make refers to enamel by the way, it is what I'm familiar with and most comfortable with. There is no right or wrong paint. 

Sorry to go on, hope this helps?

 

[fishplanebeer]

Some more great advice so thank you.

 

Just had a go on a spare wing with psi at 14-15,paint/thinner roughly 50:50 and spraying at around 2 inches away and it seems to work well once I'd found that critical point where the paint flows sufficiently to give coverage but not too much to flood. As mentioned by Jamie this is very much akin to finding the bite point of a car's clutch and then being able to hold it there for a good 20 seconds.

 

The nozzle I'm using is the 0.5mm one for the Eclipse so quite big by comparison with others but it gives a reasonable spray width of about half an inch at 2 inches distance. I just need to accept that even on a 72nd scale model it will take several passes to cover say a twin engined bomber's wing, where as with my previous flawed approach coverage would be a lot quicker. The critical thing is the finish and not how quickly I manage to spray the subject but it does feel a little like changing the (bad) habits of a life time at the moment but I will persevere and then try my hand at some really close work drawing lines and circles etc..

 

Thanks again for all your advice.

 

Regards

Colin.