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Need some helping using airbrush


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Some time last year I purchased an Iwata HP-CS airbrush.  I remember trying it on a couple bodies, but i ended up stripping one (I don't remember why) and I beleive I ended up finishing the job with rattle cans.

 

Fast forward to today and Im ready to start painting a body.  I couldnt find the color I wanted at the hobby store so I went to the local Auto paint store and purchased some single stage paint.  The body itself was primed and sanded with 44 micron(340g I believe).  

For the most part it was smooth, It was the same as the body i did earlier.  the finer grits, I can never tell if they are cutting.

 

As a person that is still learning how to use an airbrush, I decided to just paint the hood.  The paint shop had already thinned the paint.  The air Compressor I have is just a Porter Cable pancake, I installed a water trap and regulator and the pressure is set to about 17psi with the trigger depressed.

 

The issue im having is that I started with smooth surface and ended up with a surface that felt like 80 grit sandpaper.

 

here is what i started with

 

here is what i ended up with

 

This was the result of my last build, I was pretty happy with the how the paint came out, overall, i wish i would have changed the line i used for the seperation of the two tone

 

 

Im trying to figure out where i went wrong.  Ive been watching tons of video's but im not finding much on technique.  I started out with a really light spray and just keep going over different parts.  My thought is that the paint might be drying before it reaches the surface.  I dont know if my air pressure might have anything to do with it either.  I havent found anything that can suggest how to figure out what pressure to use with different thicknesses of paint.

 

Im also have trouble spraying into the little nooks and crannies of the hood scoop.  I basically had to blast it until it was covered.

 

With the Charger i showed earlier, I would start with a mist coat and gradually put on more and more, In addition to sanding between coats.

 

So in closing, Im hoping someone have share some insights and some possible solutions I can try.  Thanks for everything!

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It's hard to tell from the photos, but it could either be as Tom said, or your paint may need thinning.

I'm not sure, but it looks as if there could be a little "crazing" going on there too.

That would be the result of insufficient primer or shooting your color too heavy.

Being as it's only the hood, I would sand it, possibly thin my paint a little & try hitting it again.

Remember what Tom said, a wetter coat will probably yield a better result, as long as there is sufficient primer to handle it.

 

Steve

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Rough surface is pebbling, most times it is caused by the paint drying before it lands on the surface.

Factors that can cause it are:

Air temperature.

Shooting to far away from the surface.

Incorrect ratio of paint to thinner.

Other possible causes

With dual actions, too much air not enough paint.

And too much paint which causes over spray that gets drawn into the airflow then onto the surface of wet paint.  

 

 

Edited by Cool Hand
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When I airbrush, I keep the PSI's somewhere around the low 20's. I also like to have my paint to where it's the consistency of milk. In other words, when you swill the jar, the paint inside should wash away slightly to where you can see how much you've got in the jar.

As others have mentioned, having a good primer coat/barrier is paramount in making sure the paint doesn't craze your plastic. I'm not a big fan of having my paint "pre-thinned" by anyone. A lot of times the paint is too thin for me, and if you don't have a good primer/barrier coat on beforehand, you're sure to get crazing of the plastic without a doubt.

If it were me, I test out your method of painting on plastic spoons before trying it out on a new project. The spoons are of the same plastic as your models, and surely will save a lot of grief when you get the technique down as far as painting.

Hope all this helps!

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I would ask you to check the diameter of needle/nozzle... I have a feeling it's probably a bit smaller than .5mm. If you have in the range of .2-.3mm, you have a "detail" airbrush, and it would not be great on an entire body... you might overcompensate for a seeming lack of paint flow by holding the trigger down, which will cause more paint to be applied, but in such a tiny stream that it could easily be in the process of curing while it's hitting the surface. BTW, if you have this "sandpaper" effect in primer, you can just sand it smooth. Then, reapply where you've cut through to the raw plastic.

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I would ask you to check the diameter of needle/nozzle... I have a feeling it's probably a bit smaller than .5mm. If you have in the range of .2-.3mm, you have a "detail" airbrush, and it would not be great on an entire body... you might overcompensate for a seeming lack of paint flow by holding the trigger down, which will cause more paint to be applied, but in such a tiny stream that it could easily be in the process of curing while it's hitting the surface. BTW, if you have this "sandpaper" effect in primer, you can just sand it smooth. Then, reapply where you've cut through to the raw plastic.

I just have the needle that came with the airbrush which is a .35  I tried practicing on a sheet of paper with some black and some of that orange and it didnt look all that fine, If i held the brush within an inch of the paper the line was still pretty thick compared to others I have seen on youtube.

 

 

As far as the paint goes It is a fast drying Arcylic Enamel, ,which i didnt know until i just looked at the label, and its already pretty runny, i barely get any build up on the tooth pick.

 

 

 

So at this point things i should prolly try are:

find a larger needle?

spray on spoons is simple enough

i can try bumping up the air pressure to 20ish

spraying closer to the object

 

 

 

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I just have the needle that came with the airbrush which is a .35  I tried practicing on a sheet of paper with some black and some of that orange and it didnt look all that fine, If i held the brush within an inch of the paper the line was still pretty thick compared to others I have seen on youtube.

As far as the paint goes It is a fast drying Arcylic Enamel, ,which i didnt know until i just looked at the label, and its already pretty runny, i barely get any build up on the tooth pick.

So at this point things i should prolly try are:

find a larger needle?

spray on spoons is simple enough

i can try bumping up the air pressure to 20ish

spraying closer to the object

The only time I use my Krome (.23mm) is when I need to get really close and minimize overspray. I would never consider using this brush for an entire body. In fact, I wouldn't even do a hood with it! My favorite combo right now is .75mm, which comes stock in my Anthem, and I have changed out the standard n/n in my Patriot (comes with a .5mm) to a .75mm. According to the Iwata online manual, the only option for this brush is a .5mm, which would help but I have 2 .5mm Iwata airbrushes, and they are very nice, but I get more mileage out of the .75mm setups, and there's less of a problem with heavier paints. Also, the manual states that 35psi is the recommended compressor setting, and the brush can take up to 60psi. 

 

Edited by fseva
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I started with a Badger Patriot 105 with a 0.5 mm tip. Too small for shooting a model car body. Bought a Paasche H with a #5 tip which is 1.06 mm. I've had great success from the first time I used it. I've been experimenting with the #3 tip which is 0.64 mm as well.

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Sounds like the Paint is too heavy for the brush and that its drying before it hits the body. You need to thin out the paint to make it flow with the HP-CS. You may also go and buy a larger needle for the Iwata. I know for a fact that they make a .5mm for it. You will need the needle, the jet and the housing. It should set you back around $40.00 to $50.00. I would also dial up the the PSI on the compressor I run mine between 25 and 30 psi.

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The .5 needle/nozzle from an Iwata Revolution series is cross referenced as the optional set for the Iwata HP-CS. I have done this to my HP-CS, and it is much more forgiving in terms of paint viscosity. You can download the parts/users manual for an Iwata Revolution. This will give you the Iwata part numbers for the needle, nozzle and nozzle cap. Hope this helps.

I just found the information for the 0.5 needle. The Iwata part number is I 617 1

Edited by Bill Eh?
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I decided to try again, i sanded quite a bit on the hood to get as much of the orange peel off as i could.  This time instead of a bunch of light coats, I went full blast.  It turned out considerably better, but i still have some orange peel.  

 

 

I also went out and bought the .5mm needle upgrade, Im gonna try that and prolly thin the paint a little more.  Here's hoping things get better rather then worse.

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I decided to try again, i sanded quite a bit on the hood to get as much of the orange peel off as i could.  This time instead of a bunch of light coats, I went full blast.  It turned out considerably better, but i still have some orange peel.  

I also went out and bought the .5mm needle upgrade, Im gonna try that and prolly thin the paint a little more.  Here's hoping things get better rather then worse.

It will not get worse... trust me... you've learned a lot and now all you have to do is remember to apply what you've learned the next time you paint.

BTW, if by "went full blast", you are referring to using a rattle can, then all I can suggest is that you find a happy medium between light mist coats and wet coats. You should build up slowly with mist coats, and then go for a single wet coat that will remain very glossy after it has dried. This way, you won't get heavy build-ups of clear from staying too long in one place while spraying.

Good to see that you invested in a .5mm needle/nozzle. However, remember that this is still going to apply much less paint in a single stroke than a ratlle can would. That's why rattle cans generally don't cause coarse dry finishes - because their nozzles are super-big and you really apply a lot of material with a single stroke. For this reason, I have stopped trying to airbrush Tamiya's primers - even with a .75mm setup, I can't seem to get enough material on before the dry coarse look strikes. 

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