Ventilation

Patience

I'd go along with everything said except for the gravity feed airbrush.  I'm afraid I have to disagree with Keilau on that.  After having a chance to use both, I still prefer my siphon fed for general work.  And it seems that there are a lot of people doing fine with external mix brushes.  So I think it's a matter of personal preference rather than a requirement.

Don 

doc-hm3 wrote:

Don, one of the advantages of a gravity feed "AB" is that you use about half as much paint as you do with a siphon feed "AB".

Doc,

This is a common myth.  I did an experiment.  I put ten drops of water in the 1/4 oz. cup on my siphon brush.  I sprayed it slowly into a small bottle.  Then I measured the water in the bottle and there were 8 drops.  Only 2 drops stayed in the brush or were lost.  If you have a siphon airbrush, try it yourself.

Another possible reason that people tend to use more paint with a siphon airbrush is that typically siphon brushes are fitted with larger nozzles than gravity fed brushes, so it's easier to spray a larger quantity.  But the larger nozzle means they are less fussy about thinning.  And usually the brush will accept a smaller size if that is what you prefer.

Gravity fed airbrushes are great if you prefer them, and especially if you need to do really fine lines.  But they are certainly not necessary for most modeling.

Don 

Bgrigg wrote:

I have both kinds, and I think what Doc meant was that you typically waste less paint with a gravity fed brush. Water is not paint, paint is by far "stickier" and if you duplicate the experiment with paint you'll find you'll use more with the siphon. Let's say I'm using my trusty old siphon fed Badger 150 with the color cup. I have to put enough paint in the cup to cover the siphon tube. After spraying, I am left with whatever paint remains in the color cup, paint in the cup's siphon tube, and the paint in the 150's siphon tube out to the tip of the AB. If I use my gravity fed 100LG (which has the exact same needle and nozzle as the 150 BTW) I can put less paint in the cup to begin with as I'm not concerned with creating suction. After spraying, I am left with whatever paint stuck to the cup, and the short distance from the cup to the tip. We're not talking about a lot of paint, but there is a small saving in both paint and cleanup time. Not enough to sway my purchase from one to the other, but if I'm going to be spraying only a small amount of a color, the 100 is the one I pull out to use. The difference is line size is effectively nil, at least in my hands!

I agree that paint is stickier than water and some will stick to the sides of the cup.  But this will be true for either type brush.  And some will stick to the feed tube, which is a slightly longer path for the siphon.  But it's got to be a pretty small difference.  And it takes very little paint to cover the siphon tube in a Badger cup.

Paint would be a bit more tricky to test with as it would stick to other things like the eye dropper and the small bottle.  I might be able to compensate for that but it's probably not worth the trouble. 

As I said, I have both a siphon and a gravity fed brush, and they're both fine airbrushes.  And I agree, if I only need a tiny amount of paint I will reach for the gravity brush.  And it is a little easier to clean because it doesn't have the separate cup.  I just don't think it's fair when people claim that a gravity fed brush wastes a lot less paint. And I see that a lot.  As you wrote,"We're not talking about a lot of paint".

And I also have found that, given the same nozzle, the difference in line size is nil.

I doesn't matter to me which type people select.  But I don't think they should be led to believe that a gravity fed brush will give a big savings in paint.  And I also don't think they should be led to believe that it will give superior results just because it's gravity fed.

Don 

Don Wheeler wrote:

doc-hm3 wrote:  Don, one of the advantages of a gravity feed "AB" is that you use about half as much paint as you do with a siphon feed "AB". Doc, This is a common myth.  I did an experiment.  I put ten drops of water in the 1/4 oz. cup on my siphon brush.  I sprayed it slowly into a small bottle.  Then I measured the water in the bottle and there were 8 drops.  Only 2 drops stayed in the brush or were lost.  If you have a siphon airbrush, try it yourself. Another possible reason that people tend to use more paint with a siphon airbrush is that typically siphon brushes are fitted with larger nozzles than gravity fed brushes, so it's easier to spray a larger quantity.  But the larger nozzle means they are less fussy about thinning.  And usually the brush will accept a smaller size if that is what you prefer. Gravity fed airbrushes are great if you prefer them, and especially if you need to do really fine lines.  But they are certainly not necessary for most modeling. Don

The problem Don is that the siphon tube in a metal color cup on a siphon-feed airbrush does not get down to the last drop so to speak as a gravity feed does. If you put 10 drops of thinned, mixed paint into that same color cup you won't get much painting done. On the other hand if you put those same 10 drops in say, a Badger 360, you will get much more painting done as the paint is feeding directly into the needle tube. 

Let me also add that there is a reason illustrators use gravity feed airbrushes and part of what I said is the reason. That and the fact that less pressure is needed. 

By the way, I have seven gravity-feed airbrushes and seven siphon-feed airbrushes and as you said it is all personal preference. You do use far less paint in a gravity-feed though in my 20 years of experience with airbrushes.

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