Which Is Better Siphon Feed Vs Gravity Feed Airbrush
When trying to determine whether siphon feed or gravity feed is better for painting models or doing any other creative airbrush work it comes down to more than one factor, although there will undoubtedly be one or two ‘main’ factors that are most relevant to you. (see the quick reference table later in the article! 👍)
Choosing between the two airbrush types can be daunting, even when you get your head around the differences in operations between the two there are still a number of variables that will dictate what is better for your own requirements in airbrushing models, a siphon feed or gravity feed. 🤔
In this detailed article on choosing the best airbrush for models with respects to siphon feed or gravity feed, we’ll look at the following:
- The Differences Between Siphon Feed And Gravity Feed Airbrushes;
- The Advantage And Disadvantages Of Each Feed Type:
- Minimum air pressure limitations, which can lead to limitations in…
- Level of fine detail airbrushing required;
- Paint wastage
- Overspray
- Minimum paint required
- Mix and dilute on the fly;
- Paint spill challenges;
- Speed of colour changes;
- Paint volume requirements
- Custom mixed paint;
- Paint bottle/cup getting in the way;
- Cleaning
- General feel;
- Your budget;
- Quick Reference Table – figuring out which airbrush feed type is best for YOU;
- Siphon Feed Vs Gravity Feed Paint Finish Quality
- Other Airbrush Considerations;
What is the difference between siphon feed and gravity feed airbrushes
The difference between a siphon feed and gravity feed airbrush is that a siphon feed airbrush has the paint holder hanging below the airbrush and relies entirely on air pressure to pull the paint out of the holder, and a gravity feed has the paint holder on top of the airbrush and uses a combination of gravity and air pressure to draw the paint from the holder into the mixing area.
What these two names are essentially describing, siphon feed and gravity feed, is the method of getting the paint from the paint holder, or cup, to the area of the airbrush where the paint mixes with the air and atomises.
There is a third feed type called a “side feed” airbrush, which is an airbrush where the paint cup feeds the paint into an internal mix paint atomisation chamber from the side of the airbrush.
These are not common types of airbrushes and when looking for an airbrush to buy for scale model painting you will almost always be presented with siphon feed or gravity feed airbrushes and not a side feed.
So without further ado let’s dive straight in and look at the advantages and disadvantages of siphon feed vs gravity feed airbrushes…
The advantages and disadvantages of siphon feed vs gravity feed airbrushes
Both siphon feed and gravity feed airbrushes have their strengths and weaknesses, and will lend themselves better to a specific modeling style, task and budget.
Before you invest money into new airbrushing equipment it’s important to get quickly up to speed on the factors that will dictate which feed type of airbrush you end up with.
I look at all of these factors in concise sections below and then follow up with comparison tables to help you quickly figure out what’s best for you personally.
Let’s dive straight in, and first up we’re looking at air pressure advantages and limitations on both feed types of airbrush…
Minimum Air Pressure Limitations (which can lead to limitations in…)
All other things being equal a gravity feed airbrush can usually operate (i.e. properly atomise the paint) at a lower pressure than a siphon feed.
A siphon feed relies on the pressure going through the airbrush to ‘pull’ the paint up and out of the jar hanging underneath.
This means there is always going to be a lower limit of air pressure required simply to get any paint to come out at all.
A gravity feed airbrush will also have a lower limit, however the reasoning is different and the outcome is different.
A gravity feed airbrush has gravity helping rather than hindering the flow of paint, and so the amount of pressure required is generally less than a siphon feed.
The lower limit or air pressure on a gravity feed airbrush is therefore dictated by the viscosity (thin-ness) of the paint.
To be precise, the lower limit of air pressure on a gravity feed airbrush will be dictated by the use of the thinnest paint possible that still gives good enough coverage (i.e. doesn’t need a million coats to properly paint the piece).
It should be noted that when considering air pressure limitations in this section of the article we’re assuming that both feed types are using the same paint with the same thinning ratio, and we’ve established that almost always the gravity feed will spray properly with the lower pressure.
Is this the case on every airbrush of each type?
No.
For example, some siphon feed airbrushes are designed exceptionally well and will require less pressure to properly atomise the paint than some lower budget gravity feed airbrushes.
There is very strong anecdotal evidence, at least, that the Badger 150 siphon feed airbrush gives very good results at low pressures with the smallest of its three included needle sizes.
You can check the going price of the Badger Air-Brush Co. 150 model on Amazon here.
And on the flip side some lower budget gravity feed airbrushes will still need a relatively high air pressure to get the paint to properly flow and atomise, simply due to poor design or engineering.
Essentially, as is usually the case, you get what you pay for, and to get the best results and longevity out of your airbrush it’s worth your while to pay a little extra for a name brand item.
The final rule of thumb… more often than not gravity feed airbrushes operate properly on lower pressure settings (even if slight) than siphon feed.
Yeah ok Mark… well so what if we can get lower pressure?
Here’s the main reason you ‘might’ want lower pressure
👉 Related: learn how to set your airbrushing air pressure for perfect results!
Getting Fine Detail And Lines From Your Airbrush
It’s generally accepted that gravity feed airbrushes can provide you with finer details and lines than siphon feed airbrushes.
This is because high quality detail work is best achieved with the lowest possible air pressure and when holding the airbrush as close as possible to the item being painted.
Given an airbrush sprays paint in a cone shape (or some iteration of it) it makes sense that you want to get as close as possible to the item so that the paint doesn’t have time to spread and fan out.
However if you have too much pressure up close you’ll put far too much paint on in one spot causing spidering and runs, and possibly loss of detail on the model part you’re painting (think over-filled panel lines, or a raised rivet sitting in thick paint).
Typically speaking, as noted in the section above, the lowest pressures are available from a gravity feed airbrush, so it stands to reason that you’ll get the best results from a gravity feed.
Of course this is not the case 100% of the time, and the excellently engineered siphon feed airbrushes available (which may be a little more pricey) can give high quality detailed airbrushing results, as is the case with the Badger 150 airbrush with the fine needle option shown in the above section.
👉 Related: Get all the info you need on how to airbrush find detail and lines.
Paint wastage
A little bit of paint wastage during an airbrushing session isn’t a huge deal.
However, if you add those little bits up over every spray session you do for your entire life it could add up to significant amounts (litres even?) of wasted paint over a lifetime for even the casual modeler.
Here’s how you’ll get paint wastage and which feed-type of airbrush is best and worst when it comes to this particular problem…
Overspray
Overspray when airbrushing refers to the portion of paint that is sprayed but doesn’t land on the part your trying to get paint on to.
It’s easy to see how this could be a problem with tiny parts that are being airbrushes, where a small portion of the paint reaches the part perfectly, and does do a great job in painting the part, however there is a large component of the paint that simply misses the part and ‘oversprays’.
In the context of siphon and gravity feed airbrushes, overspray is caused for two reasons:
- As noted earlier, a siphon feed airbrush will typically need a greater air pressure to atomise the paint properly, all other things being equal. If you’re airbrushing at a higher pressure that means more paint is being sprayed for a given time period. More paint means more overspray, simple as that.
- As the minimum air pressure required is generally higher on a siphon feed airbrush (in order to suck the paint out of the paint bottle) this means you ‘may’ be limited on how small a nozzle and needle size you can go on the siphon feed option. So, on average, if a siphon feed takes a larger nozzle and needle size then it will spray more paint by default. As before, more paint means more overspray. Note that for this particular point we’re talking averages, and if the siphon feed airbrush you’re looking at comes with a small nozzle and needle combination then this aspect of overspray is obviously less of a problem.
Minimum Paint Required
In a gravity feed airbrush the paint is sucked out of the bottom of the cup which is mounted on top of the airbrush.
This means that essentially all of the paint that you load into the cup will get used.
However a siphon fed airbrush relies on a paint tube with an end sitting in the bottom of the paint jar to collect as much of the paint as it can when the airbrush trigger is pressed.
The reality of this situation is that despite siphon feed airbrushes today being very good at collection the majority of the paint, they won’t be able to get it all.
This can be especially noticeable if you move your hand around to a lot of different angles during painting to get the best coverage, thereby causing the paint the jar to swish around the bottom and potentially swishing away from the end of the paint tube.
The short of it is… there’ll be more paint wastage in a siphon feed airbrush than compared to a gravity feed airbrush where there is practically no paint wastage with regards to the location of paint container.
Mixing & Diluting Paint On The Fly;
To be fair, it’s possible to mix and dilute your paint half way through a spray session on both siphon feed and gravity feed airbrushes, however each type has a benefit and a drawback.
The advantage to a gravity feed is convenience, given you can rack the airbrush and the cap sits there perfectly ready to accept anything else you want to put into it for thinning or altering the colour.
However the siphon feed bottle has to be undone and the mixing completed away from the airbrush, and the remainder of the paint in the paint tube must blown out (wasted essentially) otherwise it may drip and cause a big mess while the bottle isn’t attached.
This is not necessarily a huge deal, it’s just not as efficient when compared to a gravity feed.
As for the advantages of a siphon feed, they also relate to the fact that you need to do the mixing away from the airbrush.
When you take the siphon feed paint bottle away and do your mixing you have the opportunity to properly clean out the paint tube on your airbrush, so it’s completely ready for the new colour or viscosity of paint.
However with a gravity feed airbrush, if you mix the new paint into the cup that’s connected to the airbrush you’re stuck with the paint still in the system between the airbrush cop and the nozzle.
You’ll have to blow this paint out before you get to the new paint that is either a different colour or different viscosity.
To do this properly you need test spray onto a scrap item, and try to observe when the newly coloured paint or different viscosity paint starts to flow out of the nozzle, which can be challenging is the change you’ve made is only minor.
I’ve personally found that if I’ve added paint or thinner to change the thinning ratio it’s fairly easy to tell the different during a test spray of a gravity feed airbrush.
However I have run into minor problems with colour changes on the fly, whereby I didn’t give it enough time for the properly coloured paint to come through, or perhaps it was a bit blotchy with slightly different colours.
At the end of the day, based on my experience it all comes down to how often you think you’ll need to alter the colour of your paint on the fly, as this is more the challenge than diluting or thickening your paint on the fly.
If you think you’ll be altering your colours a lot then go with the siphon feed and clean out the paint tube between colour changes, or if you’ll almost always be using premixed colours then the gravity feed would be my choice.
For me personally I don’t often mix colours when airbrushing scale models of any kind, so for this particular point I would always go with the gravity feed.
Paint Spill Likelihood;
On a siphon feed airbrush the paint is fully contained in the paint bottle except for a small breather hole in the top, which allows for pressure equalisation in the bottle and proper paint flow.
You would have to move the airbrush around to some fairly acute angles while painting to get the paint to come out of the tiny breather hole, and in reality this will not commonly happen.
And if it does, well the hole is quite small and you’re not going to have a lot of paint come out rapidly thankfully.
However the gravity feed isn’t always as forgiving.
Sure, most if not all gravity feed airbrushes have a cap, or lid, that you can secure to the top of the paint cup… but if you’re like me 😎… you never use it. 🙄
This usually doesn’t present a problem, except when the cup is particularly full and you’re moving the airbrush around a fair bit while spraying.
If you find yourself in this position don’t be at all surprised if you have paint slopping over the side of the cup and making a terrible mess.
If you the gravity feed lid on the paint cup this problem almost entirely goes away however, except for the little breathing hole in the lid which is essentially the same as the breathing hole a siphon feed paint bottle has.
In reality though a little paint can leak out of the breather hole of either the siphon feed or gravity feed paint holder, but given a siphon feed paint bottle will usually hold more than a gravity feed cup, you’ll likely get slightly less problems with a siphon feed unit.
Speed Of Colour Changes;
As mentioned earlier, colour changes on the fly with a gravity feed cup can present challenges in assessing when the slightly different colour is finally being sprayed.
This may present enough of a challenge to some people that a colour change on a gravity feed airbrush necessitates a full clean between each colour, even if the mixed colour change is minor (we’re not talking about pre-mixed colours here).
Additionally, when changing pre-mixed and pre-bottled colours on a gravity feed airbrush it’s always an excellent idea to do a good clean of the airbrush including quickly removing the needle and giving it a clean.
Contrast this to a siphon feed with a paint bottle mounted underneath…
The bottle of paint can be removed, and pure thinners then sucked through the paint tube left on the airbrush to clean it out…
But rather than clean the paint bottle out and add a different colour paint, you could simply have another bottle with the correct coloured paint ready to go.
No initially bottle cleaning required, just screw the new one on and go.
The time saved may not be all that significant, but if it’s important to you to change colours quickly and frequently then a siphon feed is the winner in this regard.
For airbrushing models I find that there’s no time limiting requirement for speedy colour changes, so I’m more than happy to strip down my trusty gravity feed Iwata and fully clean the needle before loading the new colour (the nozzle is not removed however).
Paint Volume Requirements;
Sometimes you just need a LOT of paint to get a particular job done, often time if you’re airbrushing a particularly large kit, or have a lot of kit parts that require the same colour such at a military vehicle.
In this instance the siphon feed wins as the paint bottles they can accommodate can be so much larger than the paint cups a siphon feel airbrush will come with.
Having said this, it’s rare that I’ll need to use more than one full cup on a gravity feed airbrush during a spraying session.
And when I do need more, it’s so seldom that it’s not enough of a reason to switch to a siphon feed for me personally.
Custom Mixed Paint;
Let’s say you need to mix a custom colour of paint, this is a task you can do in a siphon feed paint bottle or directly in the gravity feed cup.
However if you have a sizeable job and need to do a number of spray sessions with the same colour, it’s not practical do mix the colour in a gravity feed cup and then expect to mix an identical colour again a few days (or however long) later.
The simple solution to this for a gravity feed airbrush is to mix a suitable amount of paint for the entire job in a separate bottle.
However you could also do this with a dedicated paint bottle for a siphon feed airbrush whereby you don’t need to transfer paint from the bottle to the airbrush, you simply screw the paint bottle on and go (assuming it’s pre-thinned, which it should be in this case).
It’s perhaps a minor issue, but on this particular point the siphon feed airbrush just sneaks in a win.
Paint Bottle/Cup Getting In The Way;
This problem is more a matter of your style of airbrushing than anything else, and can usually be worked around by changing how you paint.
I’ve seen report of people using a siphon feed airbrush with the paint bottle hanging below, and the bottle somehow banging on their job or on the counter top or some such thing.
I have no idea how they actually achieve this but I’ll definitely conceded that just because I’ve never experienced it doesn’t mean that someone else hasn’t either.
If you’ve personally had this problem before then it’s perhaps time to switch to a gravity feed unit.
But if you’ve never used a siphon feed airbrush before then personally I wouldn’t let this potential problem concern you too much.
With regards to a gravity feed airbrush, some people report the top-mounted paint cup getting in the way of their vision when looking at and painting their item.
This would require them to be looking almost directly down the shaft of the airbrush, something I’ve never come remotely close to doing, but again, I’ll concede that some people find benefit from airbrushing in this manner.
If this is you, try switching to a siphon feed airbrush to get away from this problem, or if you’ve never used a gravity feed airbrush before then don’t pay too much heed to this problem as most people simply adapt their style such that the paint cup isn’t in the way.
Cleaning;
I’ve seen post after post of people disagreeing on which feed-type of airbrush is easier or more difficult to clean, there seems to be little consensus and it’s more a matter of personal preference.
Likely it simply comes down to the style of airbrush people most commonly use and are most familiar with.
Personally, having used both siphon feed and gravity feed types, I find that the gravity feed is easier and quickly to clean.
My Iwata Revolution airbrush disassembles extremely quickly and cleaning the paint cup and needle can be done lightning fast and without any fuss.
When it comes to the siphon feed however I do recall having issues getting the paint tube properly clean on every occasion, and I found cleaning the paint cup fiddly and problematic on more than one occasion as well, kind of like I was simply pushing the last bits of paint around the bottom of the jar rather than properly cleaning them out.
My experience is that gravity feed airbrushes are at least a little easier and more efficient for cleaning.
Your budget;
Notwithstanding the fact both siphon feed and gravity feed airbrushes are made to exceptionally high quality by the name brands and are both more than capable airbrushes for modelers, overall, siphon feed are likely to be a little easier on the wallet than their gravity fed counterparts.
However…
We’re not talking significant differences in price here.
If your budget is quite low you will still be presented with some decent options from name brands, in both siphon feed and gravity feed, at prices that won’t break the bank.
I would urge you to not go with a siphon feed airbrush simply because it’s perhaps 10-15% cheaper than its gravity fed equivalent.
In every possible occurrence you should get the airbrush that suits your style and model painting requirements, and if this means you pay a little extra then it will be worth it to you in the long run, if for no other reason than you’ll get much more satisfaction out of better paintwork and more professional looking models.
Quick Reference Table – figuring out which airbrush feed type is best for YOU;
In the quick reference table below look at the heading at the top of each section for the factor being graded, then whether the general consensus is in favour of siphon feed to gravity feed airbrushes.
The table assumes that all other variables are equal when grading each factor noted at the top.
Take your time, think about which factors will be important to you when you do your airbrushing, and using the information in the table below you’ll soon get a feel for what feed style will suit you best…
Siphon Vs Gravity Feed Airbrush Comparison Table
Siphon Feed Vs Gravity Feed Paint Finish Quality
You may be wondering right now why I’ve left this particular point right to the very end, and here’s exactly why…
It doesn’t matter.
For a given price range, low, medium or high, both siphon feed and gravity feed airbrushes will give, at the very least, a very good quality finish, to the degree that you won’t notice any real difference.
You may notice the difference between a low cost budget airbrush and a super high end break the bank airbrush, but when comparing airbrushes in the same cost category they’re all very much the same with regards to paintwork quality. 👍
Other Airbrush Choice Considerations;
So, after all of this you’d be excused for thinking we’ve covered absolutely everything, but not quite…
While this article is specifically about the feed type of the airbrush, you may also want to consider such things as:
- Single or dual trigger action: this can be beneficial if you require more fine-tuned paint delivery control;
- Nozzle/Needle swapping: some airbrushes allow for nozzle and needle size changes, others do not. You’ll have to assess your requirements for getting a better range of spray patterns and detail work from a single airbrush and see if the versatility is worthwhile for you, but of course this may come with extra cost.
👍 Check out these articles about the effect of nozzle size and needle size on airbrushes for detailed and helpful information.
But these additional factors aside, here’s my own personal view on which feed type of airbrush is better overall…
What is better, siphon feed or gravity feed for modeling? Final call…
For me, it’s gravity feed.
Many won’t agree and that’s ok, their requirements may be different, or their personal experience may be different, and that’s fine.
But personally if I have to have a single airbrush I’ll go with a gravity feed for these reasons:
- I like being able to have as much air-pressure flexibility as possible in terms of going down low;
- I want the option of being more able to produce fine detail work if required, although I’ll grant that many siphon feed airbrushes are more capable of this than my skill level;
- I really want to limit paint wastage;
- I don’t need to mix paints on the fly;
- I don’t need to change paint colours rapidly;
- I seldom need to mix custom colours, and when I do it’s only in small quantities; and
- I personally find a gravity feed airbrush quicker and easier to clean.
And one last reason that I didn’t bother mentioning until now given it’s very much a personal thing… I prefer how gravity feed airbrushes look.
And I’ve got to honestly say, we’re creatures who respond favourably to how something looks even if it’s not the best choice for us, and I’m totally guilty of this.
It’s just lucky the gravity feed is the best airbrush type for me, seems I get the best of both worlds! 😎
