What pressure?

[BBdave]

I have an Iwata airbrush .3 needle (I think)and iwata compressor i use vallejio paints how do i paint thin lines? Is the pressure critical all I seem to achieve is paint blown like you do with a straw or is the paint too thin, I seem to get the brush blocking alot if I lower the pressure.


Would I be better with a tank on the compressor?.


Dave

 

[BBdave]

Anyone???

 

[CharleyGnarlyP290]

I did the camo on my Tiger with Vallejo Model Air with my Badger Patriot. Pressure was set at 10 psi on a Co2 cylinder. Paint was straight from the bottle... no thinning. Worked like a champ. The only thing I had to do was wipe the tip occasionally to keep the dried paint off.


I have never used just a compressor with no tank, but have ready that a tank really helps.


Anymore questions let me know.

 

[stona]

I use a different paint system from you, so it is difficult for me to know how yours will react to the sorts of settings which I use. I use much higher pressures than most modellers seem to do but this enables me to spray everything from pencil lines to mottle.


Pressure AND thinning are critical,more so on acrylic paints like the Vallejo you are using. If the paint is simply being blown across the surface then it sounds like it is much too thin. I would try reducing the thinning and increasing the pressure.


As an example, using enamel paints I thin to the oft quoted 'consistency of milk' (my ratios are irrelevant to you) and spray at about 35-40 psi. You need to play with your set up and find what works for you. I would recommend using the same branded thinners as your paints, at least to start with. Initially thin to that 'milk like' consistency, if you draw the paint up the side of the cup it should run back leaving a coat on the inside of the cup, and then play with the pressure. Don't be worried about cranking it up, many airbrushes don't work properly at the low end of the pressure scale in any case.


Cheers


Steve

 

[dubster72]

Dave is it Model Air or Model Colour that you're trying to spray fine lines with?


If it's MC, then you've got a real job on your hands! I've tried that & never had any success. From what I've learned, the pigment in MC is just too coarse (relatively speaking) to airbrush.


Model Air is pre-thinned for airbrushing, but still sometimes needs thinning.


Most people say that low pressure works best for MA. We're talking under 10 PSI. Personally I don't think that airbrushes work well at such low pressures. I doubt the usual pressure regulator is accurate enough to select that kind of low pressure IMHO.


What Steve has said is absolutely true. It sounds as if the paint is too thin. The usual response is to lower the pressure, but I would try upping it to say 30PSI.


Then get in close, but be very gentle with the backwards pressure on the airbrush trigger. See how that works for you.


Failing that, buy a tinlet of Humbrol enamel, some white spirit & see how easy it is to spray fine lines


Actually I find it curious that none of the Vallejo supporters have contributed to this thread.... perhaps they know there is no easy solution?

 

[John Rixon]

Model Air is pre-thinned for airbrushing, but still sometimes needs thinning.

I'm slowly coming to the conclusion that, with a .3 or smaller nozzle, you need to thin it by default! Not by much, and some colours are needier than others (go figure!!).

Actually I find it curious that none of the Vallejo supporters have contributed to this thread.... perhaps they know there is no easy solution?

Aint that the truth!


Don't get me wrong, I quite like it as a paint, and when all goes well, it can be beautiful, but this means its a bit of a love / hate relationship, that has got me back into using brushes for 90% of the time.

 

[dubster72]

I'm slowly coming to the conclusion that, with a .3 or smaller nozzle, you need to thin it by default! Not by much, and some colours are needier than others (go figure!!).
Aint that the truth!


Don't get me wrong, I quite like it as a paint, and when all goes well, it can be beautiful, but this means its a bit of a love / hate relationship, that has got me back into using brushes for 90% of the time.

I've just done a KV-2 using Model Air for the first time & in terms of ease and finish I can see the attraction. If only it was more user friendly, especially with a H&S airbrush!

 

[John Rixon]

I've just done a KV-2 using Model Air for the first time & in terms of ease and finish I can see the attraction. If only it was more user friendly, especially with a H&S airbrush!

Yup, it will give a lovely finish, interesting that you mention H&S airbrushes, what nozzle size are you using Patrick?

 

[dubster72]

Yup, it will give a lovely finish, interesting that you mention H&S airbrushes, what nozzle size are you using Patrick?

I've the Ultra 2 in 1, so I'm using the 0.4 nozzle/needle. I generally use the 0.2 with my enamels & at first I forgot to change them over... big mistake... huge!

 

[CharleyGnarlyP290]

I have had a love hate relationship with Vallejo... until recently. I actually wrote a bunch about my problems, what I thought was causing them, and my solutions. I am still experimenting with them, but I have got to the point where I can spray them consistently and get a nice paint job.


Maybe I will copy and paste the stuff I posted on another forum... I really hate to type.

 

[John Rixon]

I've the Ultra 2 in 1, so I'm using the 0.4 nozzle/needle. I generally use the 0.2 with my enamels & at first I forgot to change them over... big mistake... huge!

I think the 0.2 nozzle is a big ask for varying viscosity paints (which I believe Vallejo are) Im sticking with the 0.4 from now on, if I use it at all! I never have to do fine lines, so not an issue really, except the finger control needs to be, like, well delicate innit?

 

[John Rixon]

I have had a love hate relationship with Vallejo... until recently. I actually wrote a bunch about my problems, what I thought was causing them, and my solutions. I am still experimenting with them, but I have got to the point where I can spray them consistently and get a nice paint job.
Maybe I will copy and paste the stuff I posted on another forum... I really hate to type.

I'm sure folks will be interested in your findings Brett, there's no substitute for empirical experience!

 

[dubster72]

I think the 0.2 nozzle is a big ask for varying viscosity paints (which I believe Vallejo are) Im sticking with the 0.4 from now on, if I use it at all! I never have to do fine lines, so not an issue really, except the finger control needs to be, like, well delicate innit?

Spoken like a real Londoner!

 

[BBdave]

I have both model air and colour and use Vallejo thinners I will try increasing the pressure and have a practice. I have used model air neat but the problems are the same I generally spray around 20-25 psi but have only ever tried reducing pressure.


Dave

 

[John Rixon]

I have had a love hate relationship with Vallejo... until recently. I actually wrote a bunch about my problems, what I thought was causing them, and my solutions. I am still experimenting with them, but I have got to the point where I can spray them consistently and get a nice paint job.
Maybe I will copy and paste the stuff I posted on another forum... I really hate to type.

I have a theory! I'm going to put it to the test when I have a spare hour or so. My theory is, that when we select a colour to start a new paint job, we shake the hell out of the bottle, and then make sure there's no gunk residing in the bottom, then shake it again. This process will coat the inside of the dropper nozzle with both paint, and some of the not-quite dissolved residue. Unless the bottle is brand new, this residue will have been lurking there, exposed to what little air there is in the bottle, since we last used it, which will, in most cases be weeks! Now, when we come to squeeze the drops of paint into our airbrush, whats the first stuff to reach the bottom of our paint cup? Yup, the gunk and residue, some of which will almost certainly be part cured.


I just cleaned a nozzle out, from a varnish bottle, (retrieved from the bin, after the last frustrations) and sure enough, there was evidence of thicker varnish, and even some tiny specks of solid material (when I say tiny, I mean tiny, gnat's knacker sized, but plenty enough to trouble a 0.3 nozzle). So, my suggested regime, for those having issues is to:


1, Before shaking the bottle, open it carefully, remove the nozzle, and, with your thumb over the opening, shake the hell out of it.


2. Wash the nozzle thoroughly, really thoroughly and push a wet cocktail stick into the hole.


3. Wipe out the washed nozzle with "Plenty" Kitchen Towel (important that it is this brand, it doesn't leave traces of paper in its path like nearly every other brand).


4. replace nozzle and proceed as normal!


Having done this, I sprayed an old model all over with said varnish, and had no spluttering and no blockage. I did use the 0.4 nozzle/needle combo, but it worked fine, which, for me using Vallejo varnish, was a first.


What a shag, but it makes sense. I will be doing more with other colours...

 

[Robert1968]

When I spray ( when I have a decent compressor ) I would spray Vallejo/ Tamiya / Revell / model air/colour all at around 15psi and I've found when thinning MA/ MC you only need IMHO a couple of drops of thinners and mix very well first. I've always had a few problems with pressure but finding 15psi seems good all round. Never upped the pressure to 40psi unless cleaning the A/b


Hope this helps


Robert

 

[CharleyGnarlyP290]

I have a theory! I'm going to put it to the test when I have a spare hour or so. My theory is, that when we select a colour to start a new paint job, we shake the hell out of the bottle, and then make sure there's no gunk residing in the bottom, then shake it again. This process will coat the inside of the dropper nozzle with both paint, and some of the not-quite dissolved residue. Unless the bottle is brand new, this residue will have been lurking there, exposed to what little air there is in the bottle, since we last used it, which will, in most cases be weeks! Now, when we come to squeeze the drops of paint into our airbrush, whats the first stuff to reach the bottom of our paint cup? Yup, the gunk and residue, some of which will almost certainly be part cured.
I just cleaned a nozzle out, from a varnish bottle, (retrieved from the bin, after the last frustrations) and sure enough, there was evidence of thicker varnish, and even some tiny specks of solid material (when I say tiny, I mean tiny, gnat's knacker sized, but plenty enough to trouble a 0.3 nozzle). So, my suggested regime, for those having issues is to:


1, Before shaking the bottle, open it carefully, remove the nozzle, and, with your thumb over the opening, shake the hell out of it.


2. Wash the nozzle thoroughly, really thoroughly and push a wet cocktail stick into the hole.


3. Wipe out the washed nozzle with "Plenty" Kitchen Towel (important that it is this brand, it doesn't leave traces of paper in its path like nearly every other brand).


4. replace nozzle and proceed as normal!


Having done this, I sprayed an old model all over with said varnish, and had no spluttering and no blockage. I did use the 0.4 nozzle/needle combo, but it worked fine, which, for me using Vallejo varnish, was a first.


What a shag, but it makes sense. I will be doing more with other colours...

Ha! That is excellent. The very conclusions I came up with.


I made a video describing the problems I encountered, why I think they occurred, and what I did to overcome them.

p.s. Moderator(s) if links to videos aren't allowed, please remove or let me know and I will do it.

 

[John Rixon]

Ha! That is excellent. The very conclusions I came up with.
I made a video describing the problems I encountered, why I think they occurred, and what I did to overcome them.

p.s. Moderator(s) if links to videos aren't allowed, please remove or let me know and I will do it.

Ha! That is excellent. The very conclusions I came up with.
I made a video describing the problems I encountered, why I think they occurred, and what I did to overcome them.

p.s. Moderator(s) if links to videos aren't allowed, please remove or let me know and I will do it.

Good video Brett, and the expression "great minds think alike" springs to mind! I've been a professional artist and lecturer for longer than I care to remember, and reckon I know a thing or two about paint. This issue has been niggling at me for a while, which made me stop and give some serious thought to what the hell was going on! I knew that there was semi cured paint in the system, from my old silk-screen printing days, when somewhere in the process, you feel the inks beginning to change in their physical state, at which point, you had to stop, clean up and resume, once all was clean, with fresh ink.. What a total shag it was, but I learned a lot about the curing of resins, which, fundamentally we are talking about here. The one reason I never tried the agitator method, is that I used to do a lot of offshore sailing, during which time, I learned that the term "stainless" when used with steel, had to be taken with a huge pinch of salt. Bottom line being that there was no way I was putting anything with Fe atoms in it, in my paint!


Anyway, it's good to see a like-minded soul on the same wave length, and I think we ought to broach this with the rest of the forum.


It must be even worse for you in CA, with the ambient temperatures there, it's bad enough over here in the summer, but I am on an oil paint rendering trip at the moment, so will remain chilled!

 

[dubster72]

As I've said before (usually falling on deaf ears!), most airbrush problems are due to the main variable... the paint!

 

[CharleyGnarlyP290]

So true on the "stainless" stuff. I figure that for the amount of time the nut will be in there it should be ok. I don't drop it in until I am ready to use the paint for the first time, and since I generally use mostly the same colors in my chosen modelling subjects, the nut won't be in there long enough to do any damage... I'll use the paint up long before that.


And the ambient temps you speak of are the primary reason I use acrylics in the first place. The temps here range from as much as 110* F in the summer to freezing in the winter. Acrylics and a CO2 cylinder with a regulator allow me to spray inside the comfort of an air conditioned home.