Shopping for Airbrush and Compressor. What is preferred for Railroad Modeling?

[fontgeek]

Just so that we're all on the same page.
When you are talking about compressed air, there are a few things to consider, and a couple of different measurements that can play a big part in what or how you paint.
PSI is Pounds per Square Inch, that is the pressure rating. That tells you how fast the air is coming out of the hose.
CFM is the Cubic Feet per Minute, this is a rating of volume or air coming out of your compressor.
Lots of people are confused about these two ratings, but if you think of the air as track and field runners on the track, the PSI is telling you how fast the runners are going to go, the CFM tells you how many runners are going to be running at a time.

For big spray guns, commonly referred to as HVLP (High Volume, Low Pressure), these need a fairly high CFM, but not lots of pressure to work.

For smaller guns and brushes, they need more pressure, and less volume to atomize the paint.

The use of a spray gun or airbrush is kind of a three way balancing act.
Generally, the thicker or higher viscosity the paint, the better the coverage you get, but the tougher it is to atomize (spray), or to get detail. Because it is thicker, it takes more pressure to pull that paint through the nozzle and into the path of the air, and if the little blobs of pigment or paint are bigger than the opening in the nozzle, it probably won't go.

So you end up thinning the paint and adjusting your air pressure to find the right balance with the nozzle size on y our brush.

It doesn't really take a huge compressor to run the typical airbrush, but you need to decide what kind of work you want to do, and what kind of paint you want to use. Those are important factors when it comes to deciding which brush you should buy. You may find, like I did, that having several brushes with different capabilities was the way to go, rather than buying a brush that was kind of ok for lots of things, but not great at any of them, having brushes that could do their job, and do it really well made sense to me when I found my self banging my head against a wall because I couldn't get my one brush to do the detail I needed, or to give me the much larger coverage I needed for backdrops. My time and sanity were worth a whole lot more than the constant fight to make a brush do something it wasn't capable of doing.

No matter what anyone tells you, there is no one perfect brush for everyone and for every job, people, like railroad setups, are different, and have different needs and requirements, both in performance, and in design. I have large hands, so some of the tiny German brushes are totally wasted on me, they end up looking like a clown on one of those tiny bicycles in the circus., but I have larger brushes and spray guns that small people find overwhelming or too heavy for their use.

So, look at what your needs are, for airbrushing, your garage, etc., and decide what you need and want out of a compressor, always buy bigger than what you think you need, that way it can always cover your jobs, even if your setup grows, or you buy new tools that require more air.
Toning a big compressor down is the easy part, trying to make a tiny compressor do the work of a big one is a no go from the start.

For the airbrush itself, you might try something that's a good work horse, something that can do pretty good detail, and pretty good coverage, then, when you have gotten your feet wet, you can buy other tools and brushes as you need them. One of the great finds for me in the last couple of years was a side feed brush made by Grex, the brush and cup have teflon packing, so that they can take any paint or finish (varnishes, laquers, etc.), the brush can do some pretty amazing detail, and pretty good coverage for smaller projects, the side cup lets you paint at any angle, which I found to be amazingly helpful, especially if you have to paint something in place. When you can't casually lift the building or water tower out of it's setting, the side cup lets you paint it where it is, without the loss of paint flow.
Iwata has a similar brush for a good bit more money, but you would probably be happy either way.

If you always paint your pieces away from their setting, then maybe somehting like a Paasche VL set would do for you.
This brush comes with three needle and nozzle sizes, though their finest nozzle and needle size are still pretty large, it can do a reasonable job for some detail, and can do some very nice work for medium to medium-large coverage jobs. They run from $50-$85 for the set, and it includes the brush, three needle and nozzle sets, a hose, a holder, and a few bottles and a cup. These brushes have larger bodies on them, and some people with small hands may not like them. Ideally, get to a hobby shop, or someplace like Dick Blick that carries a variety of brushes, and see what fits your hands and needs, when in doubt ask, if a salesperson tries to force something on you, walk away. Once you know what you need, and what kind of airbrush size works for you, then finding your match becomes a whole lot easier.

You can come back here and ask your questions, I am sure that there are lots of others who would also be willing to share their knowledge.

[CandCRR]

Fontgeek,

Thank you for that detailed explination.  Over the years I have used several air brushes different people have owned but had no idea...  Now I have some idea what I am looking at when I do get around to buying an airbrush.

Someone mentioned I would need a compressor (the big one that I use to be able to use was found floating up side down in a flooded cellar last speing) with certain CFM (???) or pressure. After reading your post I assume it would depend on the type of air brush how much pressure it needs.

 

[fontgeek]

If you already have a big compressor that you are willing to use, make sure you place at least one good water trap, filter, and regulator in the system, two sets would be even better, one right at the compressor, and one at your workplace. Keep in mind that anything that goes through that compressor or hose also goes through your airbrush unless you have filtered it out of the compressed air first.

There are a few variables that you should consider when looking at an airbrush setup.
First, what kind of work do you want to do with it? Will you be painting small detail work, or big backgrounds, and will you be spraying with your paint surface up at a normal working angle, or will you have to be painting things that are at severe angles, either up or down, what kind of paint do you need or want to use, etc. All these things are important to know.

For airbrushes, they come in a variety of types and capabilities, and keep in mind that there is no perfect brush for everything, anyone who tells you there is, is either lying or ignorant. I have been airbrushing since 1973, and I teach it on a regular basis, and I have heard it a number of times, "This is the best brush for any airbrushing."

Airbrushes are typically single or double action, siphon/suction feed, or gravity feed, and internal or external mix

Single action brushes mean that the trigger or button on the brush typically control only the release of the air, with the paint volume being controlled by an adjustment knob at the back end of the brush. For those with limited mobility, or limited mechanical movement in their hands, this may be the better otpion. By pushing the trigger or button down, you release the air, and because the paint volume is already set, you release the paint at the same time. While this may be better for some, it has it's limitations too. Because you can't casually change the rate of flow of paint going through your brush, you give up the controll over easy changes in the amount of paint bieng used at any given time.

Double action brushes have the trigger or push button control two functions. Typically, pushing down releases the air, and pulling the trigger back releases the paint. The further you pull the trigger back, the more paint your airbrush releases.

The trigger for most brushes is either a push button that controls either air alone, or both air and paint, or a gun style trigger that controls both the release of the air, and the volume of paint. With a brush like the Grex XT, or the Olympos HP 102C or B, the first half of the trigger pull is strictly the release of the air, with the second half of the pull being the control of the paint volume. Like the push button type, the further you pull that trigger back, the more paint you release.
There are push button and trigger versions for both top/gravity feed brushes, and for side feed brushes.

Siphon feed brushes have the paint suspended below the brush, the air that passes through the brush, and past the fluid or paint nozzle, creates a vacuum, this vacuum pulls the paint up from the bottle or cup, and into the path of the air, where it is mixed and atomized through the nozzle cap.

The downside for this kind of brush; Because this kind of airbrush relies on suction or a vacuum to pull the paint up from the painr reservoir, it requires more air pressure, and it gives you more overspray. It, like the gravity feed brushes has limitations on the angle you spray at.

The upside for most people is that this kind of brush typically holds more paint than the typical gravity feed brush, and you can purchase multiple bottles to hold your paint for storage and use. This lets you paint with one color, rinse out your brush with water or the appropriate solvent, then plug in the bottle with your next color, and keep going.

Gravity feed brushes use gravity to push the paint down into the path of the airstream.

The upside; This method requires a good bit less air pressure to run, and because of that, it has less of a problem with the overspray than the Siphon Feed brushes.

The Downside; Because the reservoir or paint cup is above the airbrush, these brushes typically have smaller capacity for holding paint. If y ou are not working on large areas for coverage, then this may not be a real issue. Working at severe angles,up or down can also present some problems for the typical brush, because the paint source always has to be above the nozzle of the brush.

There is a third category, and it is a bit of a blend of the two mentioned above, this kind of brush is a side feed.
This has a cup that is mounted to the side of the brush rather than a fixed cup on top, or a bottle hanging below. These cups can swivel to any angle, so painting straight up to straight down is not an issue, and because the cup is offset or not directly above the airbrush, you can use cups or reservoirs of many sizes without the loss of visual access to your work. These brushes often offer the capability of working as either a siphon feed brush or as a gravity feed brush, where all you have to do is change out the paint reservoir to the desired type as needed. Like their siphon fed cousins, when they are used as a siphon feed brush, they require more air pressure to perform, and like their other cousins, the gravity feed brushes, when they are used as gravity fed brushes, they require less air pressure to perform.


There are Internal mix, and external mix brushes, the internal mix are more commonly used, but the exterior mix brushes still get used alot.

The Internal mix brushes have the paint and air mixed internally, this lets the airbrush manufacturer have tighter control on how the paint and air are combined and sprayed, but it also makes it a little tougher for you, the artist, to clean the remaining paint out of the airbrush when you are finished.

The External mix brushes do as the name implies, they mix the paint and compressed air outside of the airbrush body. You will know these by sight, they look almost robotic with an arm that extends from teh body of the airbtush, to a container of paint that has a feeder line that sticks out slightly in front of the airbrush tip. This makes the atomizeing or mixing of the paint and air much less precise, but it does make it easier to clean out the painr line and fittings because these are all exposed.



If you are going to use paints or finishes that use harsher solvents (MEK, Laquer Thinner, etc.), then make sure you get a brush or brushes that have Teflon packing/seals, this keeps the solvents from destroying the operation of your brush.


When you look at brushes, you will typically see a description for the needle/nozzle size, more often than not, this is done in milimeters. For some brushes or brands, it is done by listing the nozzle/needle size as "Fine", "Medium", or "Large". If detail capability is an issue for you, ask the manufacturer what their "Fine", "Medium", and "Large", equate to in milimeters.
Brushes will not spray finer lines than the nozzle opening size. Super small nozzle sizes mean that your brush has the capability to spray super fine lines if it has the correct paint mixture and air pressure. While this is great for fine details, it has it's downside too. The smaller the opening size, the touchier the nozzle and airbrush are to thick paint, or paint that is pourly mixed or strained. The same goes the other way, you can buy brushes with a 1.5mm nozzle opening, and they can shoot gravel, however they can't do fine detail, and don't usually handle real watery paints or finishes very well.

Do your homework, figure out what kind of paint and working conditions you have to deal with, and what kind of detail or coverage you have to deal with, and let us know. Knowledge is power, and it lets us answer your questions better, and more completely.

Whatever you do, don't buy junker brushes, you can't get parts or service for them, so as soon as they go bad, they become paperweights.

[Rex in Pinetop]

Because I'm too cheap to buy another compressor I use the big compressor with a 15 gal tank I already have.  I crank it down to 35 psi so it rarely comes on plus when it does the noise is out in the garage.  I run an air hose to my shop when I use the Badger 250 Basic Spray Gun Set.  It's overkill for sure but it works.

Rex

[CandCRR]

I am also interested in the answer to this question.  I know a lot of it may just for individual taste but I would like to know how powerful or small is practicle.  My Father use to have an aircompressor that we used to paint cars but it was very big and loud and overkill for the small airbrushes.  Don't get me wrong, it would work but I don't know what would be too small.  I have seen very small compressors but it is hard to beleive they would work well.

Thank you,

Jaime

[Greazback]

Hello,

I would like some input as to what kind of Airbrush and compressor are best suited for Model Railroading? I would like to use the Airbrush and compressor in an extra office that is approximately 15X15ft that has a window that will open for ventilation.

Thank you for your help.