Why I prefer siphon feed


Mac-Valve Maestro!
We "car people" can be very opinionated. Rarely an airbrush conversation goes without touching on either internal vs external mix or the gravity vs siphon vs side feed topics. Sometimes, these end up in passionate yet pointless debates that spill into brand loyalty. In reality, choosing the right tool for the job will depend on the required application, the user's skill, experience and personal preference among other factors. That's like the argument of whether blue cars are faster than red cars. Everybody knows blue cars are faster. :)

Personally, I use and prefer siphon feed airbrushes. Keyword "prefer". I am not an illustrator artist like the majority here. I want to learn more about it but that's another topic. I use airbrushes to paint scale models and restore items like cameras, toys, etc. So my application and thus requirements, are different than those of an illustrator or canvas artist. I paint 3D objects so there is a lot of movement: left, right, up, down, in, out, rotation, yaw, pitch and roll like an aircraft. I use heavy paints like enamels and automotive lacquers including metallics and pearls, primers, clearcoats, urethanes, etc. Those are also important factors in choosing the right brush: nozzle size, paint capacity, etc.

Here are some of the reasons why I prefer siphon feed. Some may be relevant to other people, some may just be simple preference.

Unobstructed view of what I'm doing. The cup or jar sits below, out of line of sight. Just preference.

I use the classic color cup about 90% of the time. But it is very easy to swap to a larger jar if needed.

"Higher pressure required": I consider this difference pretty much irrelevant as I use a tank compressor. Unless you are blowing the air with your lungs, a compressor that can handle 10-15psi can handle 20-25psi. I set my pressure regulator and haven't touched it in ages. Maybe this could be relevant with smaller compressors, or maybe those cute tiny little battery powered cordless units or maybe some specialized close range technique. The topic of compressors is a whole other world: CFM capacity, tank, tankless, silent, heat, moisture, etc.

I am not sold on the concept that siphon wastes a lot more paint than gravity. I do my mixing directly in the cup. Then attach and spray. I've seen many folks doing the mixture in a separate jar and then transferring to a gravity feed, leaving waste anyways in the mixing jar. When I'm done, I usually have nothing remaining in the cup or whatever is left I put back in the paint jar. Anything remaining in the cup's small tube and short passage is really such a tiny amount it has never been significant compared to the amount of paint used. But let's keep in mind, for my application I usually use considerable amounts of paint.

If I really need to use "just a drop of paint", which I have done only for fun and test purposes, I have a secret and revolutionary tip: I turn the airbrush upside down and the siphon socket becomes a tiny little gravity cup! With a medium or heavy setup, that is a short burst. (That was my lame excuse to buy a Badger 100SG cup-less gravity airbrush but that's another story)

Cleanup: Since I use heavy paints that dry rock solid pretty fast, effective cleanup is critical as these paints can clog even the biggest firehoses. I have seen small differences in the guns themselves between types. Most variations are usually from manufacturer design (ease of disassembly).
The color cup is dropped to swim in a jar of lacquer thinner for a few minutes and then cleaned with my home made custom tiny swabs. It only takes a few seconds. Most importantly, it has become routine.

That routine leads to probably the biggest reason why I prefer siphon feed, which is far more simple: That's what I first learned and used exclusively for almost 30 years!

Bottom line, it all depends on the application and your preferences.

How about you? Anybody else uses siphon feed?

Ismael "the BADGER fan"
Nice write up Ismael, I have only ever used gravity feed and most of the time I only tend to use a few drops of paint at a time and always water based acrylics :)
I'm a model builder too, but siphon feed is probably my least favorite setup. I started out with a siphon feed brush, thinking it would be the most versatile, but with time and experience, I found that not to be the case. Now my favorite is gravity feed.

The sightline compliant against gravity feeds has always puzzled me, as it seems like that would only be an issue if one were looking straight along the top of the brush like a gun sight, when in my experience one is always looking at a downward diagonal angle relative to one's dominant hand. I've never had my vision of a paint surface occluded by a paint cup. Aircaps that occlude the needle tip have always been the biggest sightline issue for me, and those are cup-agnostic.

When painting models, my experience has been that the main bugbear about spraying at extreme angles is it tends to mean holding the brush at awkward angles. Compromising your hand-eye coordination becomes an issue way before interfering with the brush's own mechanics does. Better to hold the model at an odd angle than the brush.

And the angles needed to make a gravity feed stop working are actually pretty extreme. I could see that making sense in a special effects context, where you might be dealing with huge stuff that you can't rotate (like painting the underside of a life-sized dinosaur, say), but outside of some of the extremely big RC planes, it's hard for me to imagine a context where this would be an issue in hobby modeling. Even the biggest models I've painted (1/350 Star Trek ships) wouldn't give a gravity feed issues unless I refused to flip or turn them at all while painting. And that's to say nothing of side-feeds, where you can rotate the cup to spray lierally straight up or down in a way even siphon feeds can't.

The easiest and fastest to clean of my brushes is my gravity feed Eclipse, mostly because of how direct and wide open the transition from the cup to the paint channel is. I don't have to soak anything or clean anything separately. The entire operation is the same as cleaning just the body of siphon or side feed, only easier since the "tube" is the cup itself, so if I have to I can get in there with a swab or pipette way easier. Of all the brushes I've used, it wins hands down in this area, and this is 90% of why it's my workhorse.

The biggest difference in cleaning is between brands, not cup location, I agree with that. Specifically, brands that round off edges and polish out their welds and tool marks inside the brush are WAY easier to clean than brands that don't. There's relatively little difference between cleaning my side feed micron and gravity feed Eclipse (though the Eclipse still wins), because Iwata does these extra steps. I've got two Badgers, and the side feed is easier to clean solely because the top feed has a terrible recessed internal seam between the cup and the body (and both fall behind the Iwatas). My first brush was a Paache VL, and it was hell to clean because of hard angles and undercuts inside the paint tube where paint could "hide" from cleaning, only to come out when you ran another color through it. That thing needed a full tear down and scrub-out between every color change because nothing less could stop noticeable color contamination. My Paasche H is similarly a pain because of hard angles inside the nozzles (every time I see someone recommend an H because "external mixes are easier to clean than internal mixes", I facepalm a bit).

I wouldn't wish my VL experience on anyone, but I'll bet cleaning the siphon feed Eclipse is a marginal difference to the gravity feed one.

When it comes to air pressure, I've found that being able to operate at low pressure definitely becomes important when dealing with small parts by themselves. A brush that needs high pressure and/or high volume becomes like trying to paint with a firehose when you're doing, say, close up shading on a 28mm figure (or even just trying to target primer or base color into tight spaces like necks or the medial sides of arms). I wasn't able to do that stuff at all until I switched from the VL to the Eclipse, because the VL would risk blasting tiny parts out of my hand at any pressure high enough for it to move paint smoothly. And for the same reason it was really hard to get close in general without spiderwebbing, as that would require throttling the paint volume down to the bleeding edge of what the trigger would allow me to control.

I've heard that's a brand thing too, though. I'm told the difference in pressure/volume needs between Eclipse models is tiny, whereas I know from experience the Paasche siphon models need notably higher pressure, and MUCH higher volume.

Ergonomically I like side-feed the best, because the short tip distance makes them more dexterous for detail work, but that doesn't matter for most model building spraying, which is primarily solid coats, masking, and weathering. So the ease of maintenence and operation makes a good gravity feed win for me.
Very nice write up. While I started on a siphon feed I prefer the gravity feed, But much like you I mix in the cup so very little waste of paint.
But as far as brands it is like asking a mechanic about which the like better Snap-on, Mac, Matco or Craftsman. At the end of the day they all can do the same job.
But I think use what fits you and how you work. I have tried a lot of different airbrushes over the years and the only 2 that fits me are siphon feed and gravity feed, The cup has never been an issue for my line of sight. But the side feed gives me an unbalance feel which I never could get use to.

So thank you again for you insight of your preference .
Thanks Ian, good point.

Thank you Nessus for that excellent reply. It clearly shows the differences that make every type unique and personal. The point of the quality of the tool is very important. I usually gravitate towards older color cups as they have a better finish than more recent generic ones I have acquired, making them easier to clean. That also brings the topic of cost, value, etc. which can be a whole other topic in itself. Funny you mention the Paasche H. Since many rave about it, I got one recently. I have only used it 2 or 3 times, so I am definitely not used to it. But I find it surprisingly cumbersome to clean. I knew it was a firehose, but wow! it went thru a cup of paint like a horse going thru a dog's water bowl!

Thanks Herb! You are absolutely right. The balance and feel is very important and very personal. Especially if you use it for long hours. Not easy to measure. I'm left handed. Obviously gravity feed has no impact on that and I've never had any issues with siphon or even side feed the very few times I've used it. However, I can't use the Paasche side angled color cup as it makes me holding the brush awkward. I can only use a jar on the Paasche H. I'm not aware of a Paasche "left handed" color cup but it may exist. But been such a firehose, I'm not even sure it would make sense.

I mainly painted HO scale model trains as I said in my long into when I joined here.

We used to have quite a few stores here in the 80's , never recall gravity feed being displayed , unless I wasn't looking.

I've never tried one , I never used the paint cup on any of the 13 siphon feed airbrushes I have. I used the 1 oz glass jars only.

I will agree that cleaning a siphon airbrush may be a bit more difficult , I never felt cleaning any airbrush was real easy but I only used 1 at a time and for the most part just used the Paasche H model #3 and was so used to it I never gave it much thought. It was a basic run thinner through it and back flush into the jar.
I just remembered . There is a color cup for all siphon feed that would be a right/left hand use. It has the straight pipe rather than the curved as used on the H brush . I know Badger no longer make one but I think Paasche does.
I will agree that cleaning a siphon airbrush may be a bit more difficult , I never felt cleaning any airbrush was real easy but I only used 1 at a time and for the most part just used the Paasche H model #3 and was so used to it I never gave it much thought. It was a basic run thinner through it and back flush into the jar.

How do you backflush an H? The aircap is open around the nozzle in a way that doesn't allow me to form the kind of seal needed to redirect airflow.
A paper towel over the nozzle. Just need air to flow into the bottle . If you block off the entire end air is forced into the paint bottle.
I'll give it a try. Part of the reason I considered the H a pain to clean is because I couldn't backflush it. It wouldn't fix the internal undercuts that make scrub-outs a pain, but if backflushing is good enough to at least prevent color contamination, that would make that issue at least a lot better.
I have been using a premiair g35 recently which is gravity feed because its dependable and I have enough parts to keep it easily maintained, working on a flat table with it recently it did not feel much less cumbersome than my siphon feed brushes with jars on the bottom. The hose causing similar manoeuvrability issues. I would say the easiest for me to manoeuvre is my TC model A.

I think I am not too fussy on if it is gravity or siphon feed but more that the paint cup or jar does not get in the way and that I can see what the paint is doing in it. This is partially why I am less keen on my gravity feed, as they are top cup and the way I hold them I cannot see what the paint is doing. I can see whats going on in my paint jar and a low side cup I can see what is going on and that I am not going to spill anything.

I think for this reason I prefer a side cup, but I dont mind if it is gravity or siphon, or I like a small siphon jar.

That being said, I am using my gravity feed for my current paint pal piece.
I started airbrushing with T-shirts nearly 20 years ago with a siphon feed eclipse. A siphon feed and siphon caps on the paints was pretty much a necessity for t-shirts. I later started doing more art on canvas and paper and a gravity feed is just much easier for using tiny amounts of mixed colors. I'm still amazed at how far 3 or 4 drops will go in a cm. Definitely a user preference, but even more so the task or project at hand. Like anything else.. the right tool for the job.