How to airbrush fine detail and fine lines comes down to nozzle and needle size, needle taper, air pressure and viscosity of paint, the paint type, trigger control, and the distance you hold your airbrush away from the part you’re spraying.
These are a lot of variables and it could initially be easy to get overwhelmed, BUT…
…we’ll go over each one in easy-speak so you’re learning how to airbrush fine lines in no time.
The main topics and steps we’ll cover on how to airbrush fine detail are:
- What dictates how fine a line and detail you can paint with an airbrush
- Steps To Setting Your Airbrush Up For Painting Fine Lines And Detail
- The Technique Of Expertly Airbrushing Fine Detail And Lines On Your Models
- Troubleshooting Problems When Airbrushing Fine Details And Lines
Let’s dive straight in!
What dictates how fine a line and detail you can paint with an airbrush
For the most part, all of the following factors go hand in hand to some degree: air pressure, paint to thinners ratio, airbrush feed type, needle and nozzle size.
This means that if you change one, you’ll usually have to change at least one other by some amount.
We’ll tackle each one in turn to get a crystal clear picture of how to approach the task with confidence…
Air Pressure / Viscosity Settings For Airbrushing Fine Lines
Generally speaking, the finer the line you want to airbrush, the lower the pressure needs to be such that you don’t go so low that you have paint atomisation problems.
i.e. you get spattering or a clogged nozzle.
To help alleviate this, the air pressure direction goes directly hand in hand with the paint to thinners ratio.
The lower the pressure, the more thinners you will require so that the paint atomises and flows properly, and vice-versa.
So, so far we know that for the finest detail work we want the lowest air pressure we can get, matched with a paint thinned enough that it atomises perfectly and has enough opacity to give good coverage.
The Airbrush Feed Type Impacts Airbrushing Fine Lines
By the nature of the design a siphon feed airbrush will usually require a little more pressure to get the paint into the airflow than a gravity feed type airbrush.
If the lowest pressure is what we’re chasing to get the finest lines possible then it would stand to reason that we want to use a gravity feed airbrush.
This is a good rule of thumb, but there are definitely some extremely capable siphon feed airbrushes available that are more than capable of giving very high quality fine lines, so don’t rule them out completely if you’re looking to buy a new airbrush for fine detail work.
The Size Of The Airbrush Needle And Nozzle Required For Fine Lines
While a highly experienced airbrush user can get very high quality fine detail paint work from any sized airbrush needle and nozzle, the general rule is that the finer the detail work required, the smaller the needle and nozzle combination must be.
A smaller needle and nozzle will give a finer spray pattern and allow for the spraying of finer lines much more easily for the novice and intermediate airbrush user.
Additionally, a smaller needle and nozzle requires a smaller amount of pressure to perfectly atomise the paint, which is excellent news as we’re looking for the lowest pressure possible in order to achieve the finest lines possible.
So far the best airbrush for the job is highly thinned paint sprayed with the lowest air pressure possible, from a gravity feed airbrush (not a hard and fast rule though), and with the smallest needle and nozzle combination possible.
Needle Taper Required For Airbrushing Fine Lines
Another often overlooked aspect to getting fine lines is the distance the needle takes to taper down to a point.
The longer the taper, the fine the lines can be, and vice-versa.
You may not get a lot of options when it comes to taper length however, and will likely be stuck with the needle that ships with your particular airbrush.
Don’t let this phase you though, needle taper length is usually taken into account by the manufacturer, and on small needle/nozzle airbrushes the taper will be sufficient to give you the finest lines possible with the design of the particular airbrush.
Distance From Job For Airbrushing Fine Lines
When the paint exits the nozzle it sprays in a cone shape, which, of course, expands out wider as it moves further away from the airbrush.
So for this reason you want to be a close to the item you’re airbrushing as possible so that you get the finest line possible.
This will also require you to dial the pressure down so that you don’t get spidering and runs from putting to much paint on too quickly.
Of course, this will also require thinning the paint more with the corresponding drop in pressure.
As you can see it’s all a bit of a juggling act, but we’ll take it a step at a time and get you set up to spray fine lines and detail…
Steps To Setting Your Airbrush Up For Painting Fine Lines And Detail
STEP 1: First we need to thin the paint more so we can airbrush it at a much lower pressure.
Remember that you’ll be extremely close so the paint will be fairly concentrated on a fine line, so having it thinned more (to a degree) won’t impact the opacity too significantly.
Start by adding in an extra third of the thinners on top of what you normally add.
So for example, if you mix your paint at a 50/50 paint to thinner ratio, this time mix it at around 33/66 paint to thinners ratio.
STEP 2: Reduce your air pressure by a quarter.
STEP 3: Now do your first test spray quite close to the item you’re painting, and on a surface that’s preferably not porous, and is a colour that’s a reasonably start contrast to the colour paint you’re using.
What you’re trying to find here is the lowest pressure you can use with the newly thinned paint and still get perfect atomisation.
If you get spidering, or even a perfect spray pattern, continue to drop the air pressure by a third successfully while doing a test spray each time.
Eventually you will get to a pressure setting that results in spattering paint or nozzle clogging, and this is the point where you know you’ve gone too low, and the prior air pressure setting was the perfect one for that thinning ratio.
From here you can thin the paint more and go through the same process again, this time be sure to test the paint for suitable opacity so that you don’t need to go over the same fine line a ridiculous amount of times to get proper paint coverage with the more diluted paint.
Eventually you will find the thinnest paint you can use with suitable opacity and the corresponding air pressure for perfect paint atomisation. 👍
Now it’s time to look specifically at the technique you’ll be using…
The Technique Of Expertly Airbrushing Fine Detail And Fine Lines On Your Models
There are a number of factors that are important when spraying fine lines and details, those being the distance from the item you’re painting, trigger control on a dual-action airbrush, and the overall movement of the airbrush.
Distance From The Item You’re Painting
As mentioned previously you want to be as close to the job as possible so that you get the finest line possible.
Test spraying close enough that the needle time is almost touching the surface of the item you’re painting and see if the line goes down sharply or if it’s too close and start to spider and/or run.
If it spiders simply pull the airbrush back and start again.
Fairly quickly you’ll get an idea of how close you can get before you run into problems with too much paint going down too quickly and spidering.
Trigger Control On A Dual Action Airbrush
With a dual action airbrush you can get the air flowing and allow only a hint of paint to be mixed with that air.
This allows you to avoid spidering more easily as you have very fine tuned paint volume control, and given you can reduce the amount of paint spraying out you can potentially get a little close to the job as well.
If you’re using a dual action airbrush test spraying only a small amount of paint and going a little closer to the job to see if you can get an even finer line than before.
Constant Movement Of The Airbrush
When you’re operating very close to the surface of the item you’re airbrushing it’s very easy to have too much paint spray into one spot and cause spidering.
For this reason you need to keep the airbrush constantly moving, and slowing right down or stopping may result in spidering quite easily.
Use A Blast Of Air To Remove Paint From The Needle Tip (dual action airbrushes only)
Every now and again move your dual action airbrush away from the job, and press the trigger to get air only flowing through it.
This will help to remove any paint build up on the needle tip or nozzle so that you’re not getting and problems with the spray pattern or quality of paint work.
👍 For more detailed information on how to perfectly clean an airbrush needle tip check out this in-depth article.
And speaking of potential problems, let’s take a look at the more common ones and what to do about them…
Troubleshooting Problems When Airbrushing Fine Details And Lines
These are some of the common problems you’ll come across when doing fine detail and fine line airbrushing, and what to do about them:
Spidering is when the paint hits the surface of the part you’re painting and spreads out like spiders’ legs in a number of radiating runs.
This is due to the air pressure being too high or the paint being too thin.
The first thing you should do here is actually to try spraying with the airbrush further away from the job, as this may reduce the pressure enough to drop the spidering.
If not, you’ll either have to drop the pressure or thicken up the paint you use.
If you’re getting nozzle clogging or spattering paint it means the air pressure is too low or the paint is too thick.
You should either increase the air pressure or thin the paint more.
👍 For an in-depth article on how to avoid clogging and airbrush paint spattering click this link.
Needle Condition Causing Erratic Spray Pattern
If your needle has taken even a small amount of damage or has even the tinniest of burrs you may find that this throws off your spray pattern and makes fine detail airbrushing very difficult.
You should either replace your needle, or do some maintenance on it to smooth off the burr or whatever imperfection is in your needle.
Even a speck of dirt or old dried paint in your airbrush can ruin your job or clog your airbrush if it finds its way to the nozzle.
Always ensure that your airbrush is super clean before use, and it’s always best to clean it thoroughly after every spray session or colour change.
👍 For full instructions on how to rinse and clean your airbrush between colour changes and refills check out this detailed article.
Water Traps And Moisture In the Atomised Paint
If you get water and moisture in the paint it can easily ruin your job, especially when you’re using such thinned out paint up close to the job.
If you’re finding that this is a problem then start using an airbrush compressor with a water trap installed on it to pull the moisture out of the air before it gets to your airbrush.
👍 For detailed picture instructions on how to empty and clean your water trap check out this in-depth article.
Single or Double Action Airbrush Trigger Type
With a single action airbrush you press the trigger and get full paint volume whether you want it or not.
With a dual action you have much more control and can feed a lower volume of paint into the air stream.
If you find you’re getting spidering or runs in your paint simply try using a dual action airbrush and not letting as much paint flow.
It could be all that is needed to fix the spidering problem.
👍 To learn more about the exact differences between a single-action and double-action airbrush click this link for a detailed article.
If you find that you’ve getting pooling or spidering fairly easily it could be because you’re not moving the airbrush, or simply not moving it quickly enough.
Don’t give the paint enough time to pool and spider out by keeping constant motion going as you spray.
Improvements with different paint types
Enamels tend to have more finely ground pigments in them and therefore can be airbrushed at a lower air pressure setting, all other things being equal.
This means you can get closer to the job, which then means that you can get a finer line.
So if you find that the line you’re getting from your airbrush simply isn’t fine enough, try switching to enamel paints if you’re not using them already.
There are a lot of factors that go into figuring out how to airbrush fine details and lines.
But understand the variables affecting the outcome you’ll get, and take it step by step when setting up your paint and airbrush and testing at east point along the way.
And remember that practise makes perfect, and actually ‘doing’ is the very best way to learn.
So load up that paint and get to airbrushing and pretty soon you’ll nailing the detail work! 👊