How to spray large areas?

My novice opinion is this:

• In general, Stick with what works, but to save time you might want to use a larger (3.0 - 5.0mm dia.) needle size for wider coverage
• Your presure and distance will depend on the type of paint, thinning ration, spraying evironment and climate, etc. You'll have to play around and see what works.

I live in the midwest and spray acrylics at 15-20psi with an Iwata HP-CS at a distance of 3-4 inches away on large areas. This typically works well for me.

Hope his helps.

DogTailRed2

Hi,

I'm not sure how to correctly spray large areas such as aircraft wings.

Normally I spray quite close with low pressure to ensure a slightly wet coat. But this technique means I spray in small areas. Not good for a large wing as it takes ages to cover. If I move away then the paint dries before landing. If I up the pressure I get runs and sags.

So should I thin the paint more, use less pressure and increase the distance between spray gun and target? Or am I stuck with close in work? So how do I increase the spray area and still get good coverage?

Thanks,

Ted.

Ted, I am not sure what your expectation is when spraying a larger area. To get good even coverage, you will have to spray light layers repeatedly, but it should not take ages. I would suggest that you watch some modeling airbrush video at Youtube. There are many good ones. I feel that those by Phil Flory are pretty good. Here is one of his basic. Phil uses a Harder & Steenbeck Evolution 2-in-1, which has a pretty tiny 0.2 or o.4 mm nozzle. His time looks pretty reasonable to me.

If the paint dries before hitting the model, you need some retarder fluid or switch to a modeling thinner that has retarder mixed-in. The solution pretty much depend on the airbrush and paint you use. Forum members will give you specific recommendation when you are more specific.

An airbrush with a larger nozzle and shorter taper is more forgiving. It will allow you to use thicker paint, higher pressure to cover larger area faster. The Badger Patriot 105 standard needle has a 0.76 mm nozzle for large area and still can spray pretty good detail for modeling.

Don't change everything at once, take it a step at a time. For broader coverage obviously you'll have to shoot a little further from your target. That means you're going to have to turn up the pressure a bit. If you're normally using 10psi turn it up to 15, if you normally use 15 then try 20. You're used to mixing your paints a certain way so stick with that at first. If you're spraying too dry then shoot a little heavier coat. If it's too difficult to find a balance between dry and runs then try thinning a little less. If you can't get away from dry then thin a little more.

So, broader coverage = further away. Further away = more pressure + more paint. More paint may = adjusting the mix. You may also have to speed up or slow down a bit. Change = experimentation.

Tony

I find the larger the surface the more coats I do to make it even.  However, if the wing has prominent panel lines I spray by panel.  Thus any shading difference appears to be just differences in panels, so I don't need as many coats.  That is, there is some non-uniformity, but it is more acceptable.

Sometimes I use a rattle can for preliminary coats, then wet sand with 1000 grit and only do the final coat with the airbrush.

Like another poster I use 15 to 20 psi and do not change pressure for larger surfaces. I use 15 for gloss surfaces, 20 for flats.

First, what kind of paint are you using, and what type of airbrush? 

With my Badger 100LG for example, just backing off a few more inches to about 6" distance, and pulling back a tad more on the trigger gives me sufficient coverage for most larger, wide surfaces.  If I have a really big, monotonous area to spray, I break out the 155 Anthem, which has an even broader spray pattern when close to 'wide open.'

The other factor is paints.  If you're thinning with distilled water and a drop of retarder, increasing distance shouldn't be much of an issue unless you are in a VERY dry, hot area (Texas, Arizona).  If you are using enamels, or Tamiya thinned with alcohol, be careful of too much distance.  If the paint begins to dry before reaching your subject, you'll get a grainy texture to your finish.

Me, I'd grab an empty milk jug, primer it with a rattle can, then do some experimenting with distance, trigger pull, and mixing ratio.  I wouldn't change PSI much, if at all, as long as you're getting good atomization close-in.

Good Luck!

Chris